Dissertations / Theses on the topic 'Frequency ratio measurement'
To see the other types of publications on this topic, follow the link: Frequency ratio measurement.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Frequency ratio measurement.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Blackard, Kenneth Lee. "Measurements and models of radio frequency impulsive noise inside buildings." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-08182009-040318/.
Full text
2
Wiles, Andrew Donald. "Modelling Framework for Radio Frequency Spatial Measurement." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/771.
Full textAbstract:
The main crux of this thesis was to produce a model that was capable of simulating the theoretical performance of different configurations for a spatial measurement system using radio frequency technology. It has been important to study new modalities of spatial measurement since spatial measurement systems are an enabling technology that have allowed for the creation of better medical procedures and techniques, provided valuable data for motion capture in animation and biomechanics, and have improved the quality of manufacturing processes in many industries. However, there has been room for improvement in the functional design and accuracy of spatial measurement systems that will enhance current applications and further develop new applications in medicine, research and industry. In this thesis, a modelling framework for the investigation of spatial measurement based on radio frequency signals was developed. The simulation framework was designed for the purpose of investigating different position determination algorithms and sensor geomatries. A finite element model using the FEMLAB partial differential equation modelling tool was created for a time-domain model of electromagnetic wave propagation in order to simulate the radio frequency signals travelling from a transmitting source antenna to a set of receiving antenna sensors. Electronic line signals were obtained using a simple receiving infinitesimal dipole model and input into a time difference of arrival localization algorithm. The finite element model results were validated against a set of analytical solutions for the free space case. The accuracy of the localization algorithm was measured against a set of possible applications for a potential radio frequency spatial measurement system design.
It was concluded that the simulation framework was successful should one significant deficiency be corrected in future research endeavours. A phase error was observed in the signals extracted at the receiving antenna locations. This phase error, which can be up to 40°, was attributed to the zeroth order finite elements implemented in the finite element model. This phase error can be corrected in the future if higher order vector elements are introduced into future versions of FEMLAB or via the development of custom finite element analysis software but were not implemented in this thesis due to time constraints. Other improvements were also suggested for future work.
3
Maguire, Sean Thomas George. "Attitude determination using low frequency radio polarisation measurements." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708927.
Full text
4
Hellgesson, Markus, and Daniel Andersson. "Design of automatic measurements systems for characterizing RF-components." Thesis, University West, Department of Technology, Mathematics and Computer Science, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-387.
Full text
5
Choeysakul, Chittawan. "Small reverberation chambers for radio frequency emission measurements: a radio astronomy feasibility study." Thesis, Curtin University, 2015. http://hdl.handle.net/20.500.11937/2136.
Full textAbstract:
To use a Reverberation Chamber (RC) below the Lowest Usable Frequency, this thesis applies: multiple receiving antennas; multiple EUT positions; and a modified validation procedure. Emission measurements are then possible down to the first cavity resonance. The design is based on theory and simulations, and validated by on a prototype. The longer measurement times, compare to conventional RCs are acceptable where sensitivity is of concern, e.g. in radio astronomy or defence applications.
6
Stuart, Thomas (Thomas Edward Walter). "The measurement of radio frequency complex permeability of thin round wires." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53657.
Full textAbstract:
Thesis (PhD)--University of Stellenbosch, 2003.ENGLISH ABSTRACT: This thesis is concerned with the measurement of the complex permeability of thin round wires at radio frequencies. This is of interest as such wires are used in various applications, such as absorbing chaff. Iron and nickel alloys are also used for their good tensile properties but have an undesired electromagnetic effect which needs to be characterised. Although little work has been done in this field in recent decades it remains a relevant problem. In this thesis the advantages of accurate wide-band measurements performed by automatic network analysers are applied to the field. The measurement system is a closed coaxial transmission line with a short circuit termination. The centre conductor is the wire of interest. The surface impedance of the wire is related to complex permeability and is measured using low-loss transmission line approximations applied to half-wavelength resonances. The loss associated with complex permeability is separated from conductivity by a D.C. conductivity measurement. A full wave analysis of the coaxial mode was performed and compared to measured values. The maximum error of the propagation constant was found to be 31% at the highest frequencies and was primarily due to length uncertainties. By varying parameters expected error bands around the measured permeability were found. These bands are of the order 1 and demonstrate that the system is sufficiently robust. The measurement of the permeability of two non-magnetic wires was performed and a relative permeability of 1 was found, demonstrating the correct working of the system. A steel wire was measured and compared to measurements found in literature. The permeability dropped as frequency rose as was expected, and an acceptable comparison to other measurements was made as there is no verification standard. Thus a simple measurement system that takes advantage of calibrated automatic network analyser measurements has been developed and demonstrated to work with sufficient accuracy.
AFRIKAANSE OPSOMMING: In hierdie tesis word die meting van die komplekse permeabiliteit van dun ronde drade by radio frekwensies ondersoek. Hierdie drade word in verskeie toepassings gebruik, waaronder dié van absorberende materiale. Nikkel- en ysterallooie word ook vir hul goeie breekkrageienskappe gebruik. In laasgenoemde gevalle moet die ongewenste elektromagnetiese effekte wat voorkom, gekarakteriseer word. Hoewel baie min werk in onlangse dekades gedoen is, bly die meting van die komplekse permeabiliteit 'n relevante probleem. In hierdie tesis word die voordele van akkurate wyeband metings, soos geneem deur 'n outomatiese netwerk analiseerder, toegepas in dié veld. Die meetopstelling is 'n geslote koaksiale transmissielyn, kortgesluit aan een end. Die middel geleier is die draad van belang. Die oppervlak impedansie van die draad is verwant aan die komplekse permeabiliteit, en word gemeet deur die gebruik van lae verlies transmissielyn benaderings, soos toegepas op halfgolf resonante frekwensies. Die verlies wat met die komplekse permeabiliteit geassosieer word, word van die geleidingsvermoë onderskei deur 'n G.S. meting van die geleidingsvermoë. 'n Volgolf analise van die koaksiale mode is uitgevoer en met gemete waardes vergelyk. 'n Maksimum fout van 31% by die hoogste frekwensie is in die voortplantingskonstante gevind. Hierdie volg primêr uit onsekerhede in lengte. Deur die parameters te varieer kon 'n verwagte foutband rondom die gemete permeabiliteit gevind word. Hierdie bande is van die orde 1 waaruit volg dat die stelsel 'n genoegsame robuustheid toon. Die komplekse permeabiliteit van twee nie-magnetiese drade is gemeet en 'n relatiewe permeabiliteit van 1 is gevind. Hierdie bevestig die korrekte werking van die stelsel. 'n Staal draad is opgemeet en met gepubliseerde meetresultate vergelyk. Soos verwag, verminder die permeabiliteit met 'n verhoging in frekwensie. Hoewel geen verifiëringstandaard beskikbaar is nie, is 'n aanvaarbare vergelyking met ander metings gemaak. Die produk van die navorsing is 'n metingstelsel wat, met behulp van 'n gekalibreerde outomatiese netwerk analiseerder, aanvaarbare akkuraatheid in die meting van die komplekse permeabiliteit van dun ronde drade by radio frekwensies kan verkry.
7
Tigga, Celine. "Modelling of Measurement Equipment for High Frequency Electromagnetic Fields." Thesis, Högskolan i Gävle, Avdelningen för elektronik, matematik och naturvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-18894.
Full textAbstract:
The aim of this thesis was to develop a model of a receiver which could be quickly used to analyze radiated interference levels from data captured at the output of the antenna equipment used to measure radiated energy. Active circuits were mainly used in developing this model for the ease with which the design and simulations could be carried out in OrCAD. The guiding document for the thesis work has been CISPR 16-1-1 (International Special Committee on Radio Interference part 16-1-1) which specifies the characteristics and performance of equipment for the measurement of radiated interference. The testing of this receiver model was carried out as far as possible based on the test setups recommended in CISPR, and all results have been compared with the standards laid down for the model. Using the results, it will be shown that a CISPR EMI receiver can be modeled as a simple EMI receiver consisting of filtering, mixing and detecting circuits built according to specifications.
8
Hammoudeh, A. "Millimetric wavelength mobile radio characterisation and frequency diversity propagation measurements." Thesis, University of Bath, 1990. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.256904.
Full text
9
Landin, Per. "On radio frequency behavioral modeling measurement techniques, devices and validation aspects /." Licentiate thesis, Stockholm : Skolan för elektro- och systemteknik, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11678.
Full text
10
Landin, Per N. "On Radio Frequency Behavioral Modeling : Measurement Techniques, Devices and Validation Aspects." Licentiate thesis, KTH, Signalbehandling, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11678.
Full textAbstract:
Effektförstärkare för radiofrekvensapplikationer utgör fortfarande ett av de största problemen i trådlösa kommunikationssystem. Detta beror på att dessa förstärkare är ickelinjära, har låg energieffektivitet och ger mycket distortioner. Bättre verktyg för att förstå och korrigera dessa beteenden är nödvändiga. Ett sådant verktyg är beteendemodellering. En beteendemodell kan ses som en svart låda med insignal(er) och utsignal(er). In detta fall är dessa signaler samplade basbandssignaler och den svarta lådan är en matematisk relation mellan en insignal och en utsignal. Avhandlingen behandlar några krav för beteendemodellering av nämnda system genom att presentera metoder för utvärdering och förbättring av modellernas prestanda. Detta åstadkoms genom att betrakta ett frekvensviktat felkriterium. Ett högpresterande mätsystem är också nödvändigt för experimenten. Prestandan hos det tillgängliga systemet jämförs med prestandan hos ett allmänt erkänt mätsystem, en s.k. storsignalsnätverksanalysator, genom att betrakta prestandan hos beteendemodellerna som extraheras och valideras med data från respektive mätsystem. Resultatet visar att det existerande mätsystemet har god prestanda. Ett stort problem vid beteendemodellering är att kunna sampla med tillräckligt hög hastighet. Genom att använda Zhu-Franks generaliserade samplingsteorem vid beteendemodellering kan en del av detta problem undvikas. Teoremet medför att man kan sampla med en väsentligt lägre samlingsfrekvens än vad Nyquistteoremet säger. Modeller extraheras och prestandan utvärderas genom att använda kriteriet normalized mean square error (NMSE). För stabil prediktion och korrektion av utsignalen måste robustheten hos de använda modellerna verifieras. En sådan studie som berör robustheten mot variationer i lastimpedansen har genomförts. Prestandan på direkta modeller försämras med 7 dB mätt som adjacent channel error power ratio (ACEPR). Prestanda på inversmodellen, implementerad som digital predistortion, försämras med upp till 13 dB mätt som adjacent channel power ratio (ACPR).Radio frequency (RF) power amplifiers (PA) are still the most troublesomepart of a wireless system due to their inherent nonlinearity, low powerefficiency and high distortions. Better tools are needed to understand and correct the undesirable behavior. Some of these tools are behavioral models. A behavioral model is often thought of as a black box with some inputs andsome outputs. In the case here these inputs are sampled signals which meansthat the modeling amounts to finding a mathematical relationship betweenthe input signal(s) and the output signal(s). This thesis considers some requirements for behavioral modeling of said systems by presenting methods for general performance evaluation and improvement by considering a frequency weighted error criterion. A high performance measurement system is also needed. The performance of the available system is compared to the performance of a well recognized system, the largesignal network analyzer (LSNA). The results show that the existing measurementsystem can extract behavioral models with the same performance as the LSNA and can give lower performance validation errors. Still the need for higher bandwidths drives the measurement systems to the limits, especially the digital parts. By utilizing the so called Zhu-Frank generalized sampling theorem, behavioral modeling of a PA is done by using data acquired at a sampling rate lower than the Nyquist rate. Models of a PA are extracted and the performance is evaluated using the normalized meansquare error (NMSE) criterion. For prediction and correction of the output signals the stability of the models regarding changes must be investigated. One such study considering controlled variations on the output load of the PA is done and both the predictive and corrective capabilities of the models are evaluated. The predictive capability gets up to 7 dB worse measured as adjacent channel error powerratio (ACEPR) and the corrective, as digital predistortion, gets up to 13 dB worse measured as adjacent channel power ratio (ACPR).
11
Kim, Daeyoung. "Propagation measurements and system design for long-range RF tags." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/13876.
Full text
12
Nader, Charles. "Signal Shaping and Sampling-based Measurement Techniques for Improved Radio Frequency Systems." Doctoral thesis, KTH, Signalbehandling, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-95404.
Full textAbstract:
Wireless communication systems are omnipresent in our day-to-day life, with high expectations regarding capacity, reliability and power efficiency. In order to satisfy the capacity and reliability expectations, today's wireless systems are adopting sophisticated modulation schemes, such as orthogonal frequency division multiplexing (OFDM), which shape today's wireless signals with large bandwidths and high crest factors. On top of that, it is anticipated that different wireless systems/standards will co-exist and share the same radio frequency (RF) front-end in order to reduce the network implementation cost. Such signals characteristics and systems coexistence put high requirements on the amplification stage which in best scenarios is considered weakly nonlinear. As a result, the power amplifier needs to be backed-off for linear operation. However, such power back-off reduces the operation's efficiency. Reducing the crest factor of the wireless signal and the possibility to linearize by means of digital pre-distortion the operation behavior of the power amplifier when operated near its maximum allowed continuous wave (CW) operating power range would lead to the optimal linearity and efficiency of operation. In order to achieve a good linearization performance, accurate baseband behavioral models are needed which requires measuring time domain signals whose spectra spread largely due to the nonlinear operation of the power amplifier. Such spectrum spreading, denoted by spectral regrowth, puts high requirements on today's sampling-based measurement systems as a trade-of between the sampling rate and amplitude resolution exists in today's generation of analog-to-digital converters, in addition to a limitation in the available analog bandwidth. Overcoming such measurement challenges could lead to the design of expensive measurement systems which is not favorable. In this thesis, the performance of RF transmitters is improved by combining the use of a smart crest factor reduction technique with an enhanced digital pre-distortion technique which allows operating the power amplifier near its CW 1-dB compression point, offering a significant increase in the efficiency of operation while satisfying the standard constraints on information error and spectral emission. Furthermore, the performance of RF measurement receivers is improved by reducing the requirements on the digital bandwidth by means of an evolved harmonic sampling technique, and by reducing the requirements on the analog bandwidth and design cost by means of a digital bandwidth interleaving technique and a signal separation technique based on an advanced sparse reconstruction methodology.Trådlösa kommunikationssystem förekommer överallt i vår vardag, med höga förväntningar på kapacitet, tillförlitlighet och energieffektivitet. För att uppfylla förväntningar på kapacitet och tillförlitlighet är dagens trådlösa system utrustade med avancerade modulationsmetoder, såsom Orthogonal Frequency Division Multiplexing (OFDM), vilket medför att dagens trådlösa signaler har stora bandbredder och höga toppfaktorer. Därutöver planeras det för att olika trådlösa system/standarder kommer att samexistera och samutnyttja komponenter i gränssnittet mot radiosignaler, s.k. RF front-end, för att därigenom minska kostnader för nätverk. Egenskaperna hos dessa signaler och samexisterande system ställer höga krav på förstärkarsteg som i bästa fall kan anses svagt olinjära. Som ett resultat av detta behöver effektförstärkaren arbetspunkt flyttas för förstärkaren skall arbeta i det linjära området, men en sådan förflyttning minskar systemets verkningsgrad. Genom att reducera toppfaktorn på den trådlösa signalen samt att linjärisera förstärkarsteget genom digital förförvrängning, även kallad predistortion, hos effektförstärkaren när den drivs nära sin högsta tillåtna arbetspunkt för en kontinuerlig signal (CW) kan optimal linjäritet och effektiv drift erhållas. För att uppnå god linjäriseringsprestanda krävs noggranna modeller som beskriver beteende i basbandet. Att ta fram dessa modeller kräver tidsdomänmätningar av signaler vars spektra är bredbandiga, till stor del beroende på icke-linjär drift av effektförstärkaren. Bredbandiga spektra ställer höga krav på dagens samplande mätsystem i och med kompromissen mellan samplingsfrekvens och upplösning i amplitud finns i dagens generation av analog till digital omvandlare; dessutom finns en begränsning i tillgänglig analog bandbredd. Att lösa dessa utmanande mätproblem kan leda till utformning av dyra mätsystem vilket inte är önskvärt. I denna avhandling förbättras prestandan hos en radiosändare genom en kombination av smart toppfaktorreduktion och förbättrad digital predistortionsteknik som gör det möjligt att driva effektförstärkaren nära sin 1 dB kompressionspunkt, vilket erbjuder en betydande ökning av systemets verkningsgrad samtidigt som det uppfyller standarders krav avseende vektornoggrannhet och spektral spridning. Dessutom har prestandan på mätutrustningen för radiofrekvenser (RF) förbättras genom att minska kraven på digital bandbredd med hjälp av en nyutvecklad harmonisk samplingsteknik, och genom att minska kraven på den analoga bandbredden och konstruktionskostnad med hjälp av en teknik att intersekvensera signaler i den digitala frekvensdomänen samt med en signalseparationsteknik baserad på en avancerad rekonstruktionsmetod för glesa signaler.
QC 20120605
13
Ramamoorthy, Suresh. "Measurement of energy consumption in Wireless LANs and Radio Frequency Identification systems." Thesis, Wichita State University, 2011. http://hdl.handle.net/10057/5030.
Full textAbstract:
As mobile hand-held devices such as cell phones and personal digital assistants are battery
operated, it is important to minimize their energy consumption. The limited lifetime of the battery
is always a problem for all portable devices. Although battery technology has undergone a massive
development over the years, it has not kept pace with other technologies. Therefore, research needs
to be done to use the limited life time of the battery in an efficient way.
With developments in science and technology, the power consumption of portable devices
has been brought down due to the decrease in the size of the display and optimization of components.
The trend toward smaller sizes of portable devices involved is responsible for the wireless
network interface consuming a larger share of overall power consumption of a system. In order
to optimize the power consumption of wireless communication, we should be aware of the power
consumption pattern.
Accurate energy models are required for designing and testing energy aware protocols.
The accuracy of these energy models and their contribution toward energy aware protocol design
depend on the accuracy and availability of sufficient data about power consumption of these devices.
This work contributes to the building of such a power consumption database through a
series of measurements of currently available Wireless Network Interface Cards (WNIC) and Radio
Frequency Identification Devices (RFID). These measurements also help in understanding the
behavior of these technologies at the lower levels of the network stack.Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Electrical Engineering and Computer Science.
14
Whitney, John Peter 1982. "Measurement of radio-frequency magnetic fluctuations in the VTF magnetic reconnection experiment." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32751.
Full textAbstract:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2004.Includes bibliographical references (p. 30).
In this thesis work, I designed, fabricated, and calibrated, a radio-frequency magnetic probe, subsequently used to measure magnetic turbulance in the reconnecting plasmas of the Versatile Toroidal Facility (VTF). Reconnecting Hydrogen plasmas were created, and magnetic fluctuations in all three artesian directions were measured in the 1-101)MHz range. A preliminary hodogram analysis of the fluctuation spectra found the propagation direction of low-frequency (1-5MHz) electromagnetic waves to be parallel to the direction of the plasma current, while high-frequency waves had a random distribution of propagation directions.
by John Peter Whitney.
S.B.
15
Zenteno, Efrain. "Vector Measurements for Wireless Network Devices." Licentiate thesis, KTH, Signalbehandling, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-111863.
Full textAbstract:
Wireless networks are an iconic technology of today’s modern era, theyare present in our daily activities as can be exemplified by cellular communications,wi-fi, bluetooth, and others. Vector measurements play an importantrole in the design, simulation, and testing of wireless networks and are usedto characterize key devices operating in the radio interface, such as amplifiers,filters, and mixers.Accurate characterization is the key for improving the capacity and efficiencyof wireless networks. As the demand for network capacity continuouslyincreases, the accuracy of vector measurements must also improve. Further,it is anticipated that such trends will continue in the years to come. Consequently,the wireless industry needs to include nonlinear behavior in theircharacterization and analysis, to assess and guaranty the operation of the devices,and to comply to the specifications from governmental regulations. Incontrast to linear behavior, nonlinear behavior presents an additional bandwidthrequirement because the signal bandwidth grows when it passes throughnonlinear devices. In this thesis, vector measurements for devices operatingin wireless networks are studied, emphasizing a synthetic approach for theinstrumentation. This approach enables the use of digital post-processing algorithms,which enhances the measurement accuracy and/or speed and canovercome hardware impairments. This thesis presents the design of a vectorialmeasurement system for wireless devices considering the aforementionedtrends and requirements. It also explores the advantages of the proposedapproach, describes its limitations, and discusses the digital signal processingalgorithms used to reach its final functionality. Finally, measurement resultsof the proposed setup are presented, analyzed and compared to those of modernindustrial instruments.QC 20130204
16
Nguyen, Anh Tuan. "Microwave photonic signal processing utilising recirculating delay line structure." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/11736.
Full textAbstract:
Microwave photonic signal processing, using photonic approaches to condition microwave and radio frequency signals, is attractive due to the inherent advantages of high time-bandwidth product, immunity to electromagnetic interference, and its capability to realise dynamic tuning over multi-GHz bandwidths. Additionally, since in-fibre signal processors are inherently compatible with fibre optic microwave systems, they can provide connectivity with in-built signal conditioning. These new techniques transcend the limitations of existing electronic methods, and enable new structures to be realised, which not only can process high-speed signals but which can also realise adaptive operation. The delay line structures have been exploited for microwave photonic signal processing for many years. Among various types of photonic delay line signal processing structures, the amplified recirculating delay line structure is one of the most commonly used thanks to its capability of generating numerous delayed optical signals with just two simple components, i.e. a 2x2 optical coupler, and an optical amplifier. Recently, the frequency shifting amplified recirculating delay line structure has been investigated. However, the investigation only focused in the phase noise suppression in a filter structure. In this thesis, the frequency shifting amplified recirculating delay line structure is used to improve a filter frequency response free spectral range, to develop a new approach for storing radio frequency signals, and to simultaneously measure the frequencies of multiple microwave signals. The performance of these processors is significantly improved compared to previous approaches. That is the microwave bandpass filter free spectral range is increased by 100 times, the storage time of the new radio frequency memory with less than 10 dB degradation in the signal-to-noise ratio can reach 300 µs, and the new multiple-frequency measurement receiver can offer a wide measurement range of 100 GHz together with a high resolution of 250 MHz.
17
Adegoke, Elijah. "Radio frequency channel characterization for energy harvesting in factory environments." Thesis, Loughborough University, 2018. https://dspace.lboro.ac.uk/2134/33412.
Full textAbstract:
This thesis presents ambient energy data obtained from a measurement campaign carried out at an automobile plant. At the automobile plant, ambient light, ambient temperature and ambient radio frequency were measured during the day time over two days. The measurement results showed that ambient light generated the highest DC power. For plant and operation managers at the automobile plant, the measurement data can be used in system design considerations for future energy harvesting wireless sensor nodes at the plant. In addition, wideband measurements obtained from a machine workshop are presented in this thesis. The power delay profile of the wireless channel was obtained by using a frequency domain channel sounding technique. The measurements were compared with an equivalent ray tracing model in order to validate the suitability of the commercial propagation software used in this work. Furthermore, a novel technique for mathematically recreating the time dispersion created by factory inventory in a radio frequency channel is discussed. As a wireless receiver design parameter, delay spread characterizes the amplitude and phase response of the radio channel. In wireless sensor devices, this becomes paramount, as it determines the complexity of the receiver. In reality, it is sometimes difficult to obtain full detail floor plans of factories for deterministic modelling or carry out spot measurements during building construction. As a result, radio provision may be suboptimal. The method presented in this thesis is based on 3-D fractal geometry. By employing the fractal overlaying algorithm presented, metallic objects can be placed on a floor plan so as to obtain similar radio frequency channel effects. The environment created using the fractal approach was used to estimate the amount of energy a harvesting device can accumulate in a University machine workshop space.
18
Petrin, Allen John. "Maximizing the Utility of Radio Spectrum: Broadband Spectrum Measurements and Occupancy Model for Use by Cognitive Radio." Diss., Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-07152005-135311/.
Full textAbstract:
Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2006.Dr. Stevenson J. Kenney, Committee Member ; Dr. Paul G. Steffes, Committee Chair ; Dr. Gregory D. Durgin, Committee Member ; Dr. Aaron D. Lanterman, Committee Member ; Dr. Robert G. Roper, Committee Member.
19
Vlach, Philip Thomas. "Measurement, prediction and analysis of the radio frequency electromagnetic environment outside and inside hospitals." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=26436.
Full textAbstract:
The electromagnetic environment outside and inside five urban hospitals, due to fixed, EXTERNAL TRANSMTTERS (30-1000 MHz range), was characterized by measurement. Measured fields generally remained below 130 dB$ mu$V/m (3 V/m). Four computational prediction methods, based on line-of-site free-space propagation, Uniform Geometric Theory of Diffraction, and urban clutter models, were evolved. Fields predicted outside these hospitals were compared to the measured fields. A simple line-of-sight method predicted fields within 20 dB of those measured, thereby easily providing an estimate of the worst-case fields at a hospital. The most complex of these prediction methods estimated field levels to within 10 dB.Measurements were also used to analyze signal propagation characteristics inside buildings due to INTERNAL SOURCES operating at 433, 861, and 1705 MHz. Cross-floor propagation paths, where multiple floors and walls were traversed, showed fields were independent of the transmitter-receiver separation distance. Signals measured for a separation of one floor were higher than same-floor signal levels.
20
Rutschlin, Marc. "The non-destructive measurement of the radio frequency properties of hard rock borehole cores." Thesis, Stellenbosch : Stellenbosch University, 2005. http://hdl.handle.net/10019.1/50504.
Full textAbstract:
Thesis (PhD) -- Stellenbosch University, 2005.ENGLISH ABSTRACT: The effective use of borehole radar in geophysical exploration requires accurate knowledge of the dielectric properties of the geological system in which it is employed. The attenuation and propagation velocity of pulses through rock must be known in order to plan and interpret experimental data. Conventional destructive methods for the measurement of hard rock cores require the careful preparation of samples. This firstly necessitates the selection of sampling position and the resulting estimation of rock properties based on sparse measurements, and secondly results in the loss of material and thus data. The ready availability of cylindrical borehole core samples invites the use of a nondestructive means of measuring their properties. A novel design for a flexible guarded capacitor which conforms to a core's cylindrical surface is presented here. T he proposed device has numerous advantages over previous methods. No material is lost to sample preparation and a detailed characterisation of the entire core, including inclusions and transitions between rock types, may be performed. A detailed methodology for the rapid construction of a robust capacitor is given. Guidelines for its operation to achieve repeatable and accurate measurements of the complex dielectric constant of samples of varying homogeneity in the 1- 25 MHz frequency range are presented. The increased amount of data collected from complete core samples is analysed statistically, and amongst other things allows the estimation of the rock's homogeneity. Comparisons of the dielectric properties measured in the laboratory to propagation velocity estimates obtained from crosshole borehole shoots show that a more homogeneous sample is a better predictor of bulk propagating conditions. Detailed studies of the dielectric properties of economically important diamondiferous and platiniferous geological systems show that borehole radar is a feasible tool for the high resolution delineation of ore bodies and other geological targets.
AFRIKAANSE OPSOMMING: Die effektiewe gebruik van boorgatradar in geofisiese eksplorasie benodig akkurate kennis van die dielektriese eienskappe van die geologiese sisteme waarin dit gebruik word. Kennis van die verswakking en voortplantingsnelheid van pulse deur die rots word benodig om eksperimente te beplan en gemete data te interpret eer. Vir konvensionele destruktiewe meetmetodes van harde rotskerne is noukeurige voorbereiding van monsters noodsaaklik. Hierdie proses vereis eerstens 'n keuse van meetposisies en die afskatting van rotseienskappe gebaseer op verspreide metings, en lei tweedens tot die verlies van materiaal en dus data. Die beskikbaarheid van silindriese bom·gat kernmonsters maak dit moontlik om die kerneienskappe op n nie-destruktiewe manier te meet. Die ontwerp van 'n nuwe buigbare afgeskermde kapasitor wat op 'n silindriese kernoppervlak pas, word hier voorgestel. Die toestel het verskeie voordele bo huidige metodes. Geen materiaal word gedurende monstervoorbereiding verloor nie, en 'n volledige beskywing van die eienskappe van die hele kern , met insluitings en oorgange tussen rotstipes, kan verkry word. 'n Gedetaileerde prosedure vir die vinnige konstruksie van 'n robuuste kapasitor word gegee. Die gebruik van die toestel vir herhaalbare en akkurate metings van die komplekse dielektriese konstante van verskillend homogene monsters in die 1- 25 MHz frekwensie bereik word beskryf. Die groter hoeveelheid data wat deur middel van hierdie metode van hele kernmonsters verkry kan word , word statisties geanaliseer, en laat onder andere 'n skatting van die rots se homogeniteit toe. Vergelykings van laboratoriumgemete rotseienskappe met veldskattings van voortplant ingsnelhede wys dat 'n meer homogene monster tot 'n beter afskatting van werklike voortplantingstoestande lei. Studies van die dielektriese eienskappe van ekonomies belangrike diamanthoudende en platinumryk geologiese sisteme wys dat boorgatradar geskik is vir hoe resolusie uitkenning van ertsligame en ander geologiese teikens.
21
Angelotti, Alberto Maria <1992>. "Measurement techniques for the characterization of radio frequency gallium nitride devices and power amplifiers." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amsdottorato.unibo.it/9834/1/Main.pdf.
Full textAbstract:
The rapid growth of mobile telecommunications has fueled the development of the fifth generation (5G) of standards, aiming to achieve high data rates and low latency. These capabilities make use of new regions of spectrum, wider bandwidths and spectrally efficient modulations. The deployment of 5G relies on the development of radio-frequency (RF) technology with increased performance. The broadband operation at high-power and high-frequency conditions is particularly challenging for power amplifiers (PA) in transmission stages, which seek to concurrently maximize linearity and energy efficiency.
The properties of Gallium Nitride (GaN) allow the realization of active devices with favorable characteristics in these applications. However, GaN high-electron mobility transistors (HEMTs) suffer from spurious effects such as trapping due to physical defects introduced during the HEMT growth process. Traps dynamically capture and release mobile charges depending on the applied voltages and temperature, negatively affecting the RF PA performance.
This work focuses on the development of novel measurement techniques and setups to investigate trapping behavior of GaN HEMTs and PAs. At low-frequency (LF), charge dynamics is analyzed using pulsed current transient characterizations, identifying relevant time constants in state-of-the-art GaN technologies for 5G. Instead, at high-frequency, tailored methods and setups are used in order to measure trapping effects during the operation of HEMTs and PAs in RF modulated conditions. These RF characterizations emulate application-like regimes, possibly involving the control of the device’s output load termination. Therefore, an innovative wideband active load pull (WALP) setup is developed, using the acquisition capabilities of standard vector-network-analyzers. Moreover, the implications of performing error-vector-magnitude characterizations under wideband load pull conditions are studied. Finally, an efficient implementation of a modified-Volterra model for RF PAs is presented, making use of a custom vector-fitting algorithm to simplify the nonlinear memory operators and enable their realization in simulation environments.
22
Rousseau, Moshe. "A broad-band compact range for radio frequency electromagnetic susceptibility and emission measurements." Thesis, University of Bradford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254199.
Full text
23
Roig, Gema. "ON DVB-H RADIO FREQUENCY PLANNING: : ADJUSTMENT OF A PROPAGATION MODEL THROUGH MEASUREMENT CAMPAIGN RESULTS." Thesis, University of Gävle, Department of Technology and Built Environment, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-540.
Full textAbstract:
The present Master Thesis analyzes the DVB-H radio Frequency Network Planning
problematic, studying the influence of a propagation model used in the calculation of
network coverage. In this way, the aim of this work is the design of a procedure and
algorithm to adjust a propagation model considering measurement campaigns performed in
different environments (dense-urban, urban, sub-urban and rural).
The methodology relies on the adjustment of the Xia-Bertoni propagation model
parameters using the Least Mean Square (LMS) method, considering the collected
measurements and the simulation model parameters obtained from a Geographic
Information System (GIS). Coverage simulations and measurement results are compared
using a 3-Dimensional city model (terrain and buildings) for different terrain topologies
(flat, hills and canyons) and environments.
The resulting adjusted model has been tested and compared with other common
models (COST231 and Okumura-Hata) using specific metrics, thus proving its validity for
different frequencies, environments and terrain topologies. In order to validate the
procedure and designed algorithm, this Master Thesis gathers real data from measurement
campaigns carried out in different cities: Gävle (Sweden), Bucaramanga (Colombia),
Valencia (Spain) and Munich (Germany). Besides, this work provides an insight on best
practices to perform measurement campaigns.
The outcome of this work is a useful tool in radio network planning for DVB-H
systems, which ensures reliable results in all environments and terrain topologies.
24
Gross, Eugene Joseph 1960. "OPTICAL MAGNETIC FIELD PROBE WITH LIGHT EMITTING DIODE SENSOR (RADIO FREQUENCY, FARADAY'S LAW, INCANDESCENT, TEMPERATURE COMPENSATION, INDUCTRON)." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/276393.
Full text
25
Wei, Xiaoyun Niu Guofu. "On-wafer S-parameter measurement using four-port technique and intermodulation linearity of RF CMOS." Auburn, Ala, 2008. http://hdl.handle.net/10415/1448.
Full text
26
Chen, Youjie. "Micro Assembly for Radio Frequency Electronics : Characterization of Bond Wires." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-257875.
Full textAbstract:
Due to the increasing number of components involved in Radio Frequency design, integration and packaging become an important topic of developing power-efficient and cost-effective solutions. Furthermore, interconnections are a key factor in such a topic because they are heavily used in Radio Frequency engineering, especially in the Fifth Generation. Among the interconnections, bond wires are one of the most commonly used.In micro assembly design, it is crucial to understand and model the behavior of each component, including interconnections. Radio Frequency engineers usually use the bond wire models in the software directly without questioning if the model actually has the same behavior as the fabricated one. Therefore, how to accurately model and characterize the bond wires becomes valuable, and furthermore, how the physical dimensions affect the transmission performance. This Master’s thesis project aims to solve this problem by building simple models for single bond wire and double bond wires with coupling, and verifying them by electromagnetic simulation and measurement.The project has built bond wire models in Matlab and in electromagnetic simulators NI AWR and ANSYS HFSS. The actual test structures are also fabricated using the bonding machine, and measured by vector network analyzer. A sufficient amount of data has been collected from these sources and then analyzed. The proposed analytical model of bond wires is valid after comparing its results with those from simulation and measurement. In addition, the effect of the loop height and separation distance on the transmission performance is studied and has a well verified conclusion.This thesis work will be helpful to Radio Frequency engineers, who use bond wires in the micro assembly of their design. They would be able to characterize the bond wires more accurately and adjust the physical dimensions in order to achieve the desired performance.På grund av det ökande antalet komponenter i radiofrekvensdesign, integration och förpackning blivit ett viktigt ämne för att utveckla energieffektiva och kostnadseffektiva lösningar. Sammankopplingar är en nyckelfaktor i ett sådant ämne, eftersom de är starkt används i radiofrekvensteknik. Bland dem, bondtrådar är en av de vanligaste.Det är viktigt att förstå och modellera beteendet hos varje komponent. Därför hur att noggrant modellera och karakterisera bondtrådarna blir ett värdefullt problem, och dessutom, hur de fysiska dimensionerna påverkar överföringsprestanda.Projektet har byggt bondtrådsmodeller i Matlab och i elektromagnetiska simulatorer NI AWR och ANSYS HFSS. De faktiska teststrukturerna tillverkas också med hjälp av bindningsmaskinen och mäts av vektornätverksanalysatorn. Den föreslagna analysmodellen för bindningstrådar är giltig efter att ha jämfört dess resultat med dem från simulering och mätning. Dessutom studeras effekten av slinghöjden och separationsavståndet på transmissionens prestanda och har en väl verifierad slutsats.
27
Yılmazer, Şafak Enes. "Integrated Coverage Measurement and Analysis System for Outdoor Coverage WLAN." Thesis, Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-2185.
Full textAbstract:
Daily usage of Wireless Local Area Networks (WLAN) in business life for specific purposes has became much more critical than before since it is sometimes crucial to have wireless connectivity and seamless roaming around the working environment. In this thesis, steps required in order to design and implement a large scale outdoor IEEE 802.11g WLAN will be shown. This WLAN project has been deployed in north of Sweden and target coverage was an open area consisting of a deep pit mine, connecting roads, workshops, offices, dumps and storage areas. All telecommunications equipment used in this project is from the manufacturer Cisco using centralized solution. The special purpose of this project is to collect and analyze a series of coverage measurement data and correlate this data to predict the coverage area. Linux bash scripting and Gnuplot has been used to analyze coverage data. Finally, WRAP spectrum management and radio planning software has been used in modeling and designing of the whole network.
28
McCormick, Jackson C. "Spatial and temporal ionospheric monitoring using broadband sferic measurements." Thesis, Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54469.
Full textAbstract:
The objective of this thesis is to use radio emissions from lightning, known as `radio atmospherics' or `sferics', to study the temporal and spatial variation of the lower ionosphere, a layer of ionized atmosphere beginning at $\sim$70 km altitude (D-region). Very Low Frequency (VLF, 3$-$30kHz) radio waves are a useful diagnostic for lower ionospheric monitoring due to their reflection from this region and global propagation. Traditionally, the lower ionosphere has been sensed using single-frequency VLF transmitters allowing for analysis of a single propagation path, as there are only a small number of transmitters.
A lightning stroke, however, releases an intense amount of impulsive broadband VLF radio energy in the form of a sferic, which propagates through the Earth-ionosphere waveguide. Lightning is globally distributed and very frequent, so a sferic is therefore also a useful diagnostic of the D-region. This is true both for ambient or quiet conditions, and for ionospheric perturbations such as solar flare x-ray bursts. Lightning strokes effectively act as separate VLF transmitting sources. As such, they uniquely provide the ability to add a spatial component to ionospheric remote sensing, in addition to their broadband signature which cannot be achieved with man-made transmitters.
We describe the methods of processing in detail. As an example, we analyze a solar flare during which time there is a significant change in magnitude and frequency content of sferics. This disturbance varies with distance from the source, as well as time. We describe the methods of processing in detail, and show results at Palmer Station, Antarctica for both a quiet and active solar day.
29
Gueye, Serigne Bira. "Electron-Radio-Frequency Quadrupole (ERFQ) linear accelerator: theory, design and measurements for the GHz region." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=980255554.
Full text
30
Jacobs, Brett William. "Phase-resolved measurements of ion dynamics in radio frequency plasma sheaths by laser-induced fluorescence." Diss., Restricted to subscribing institutions, 2010. http://proquest.umi.com/pqdweb?did=2023768081&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
Full text
31
Harle, Thomas. "Radio frequency plasma thrusters : performance evaluation of low magnetic field mode operation through direct thrust measurements." Thesis, University of Surrey, 2015. http://epubs.surrey.ac.uk/807990/.
Full textAbstract:
This thesis describes an experimental investigation into the performance of a radio frequency plasma thruster (RFPT). This type of thruster does not rely on the use of high voltage ion acceleration grids or beam neutralisers which are typically life limiting elements of an electric thruster. The RFPT excites an atomic or molecular gas into a plasma using an external RF antenna. This plasma is contained by a cylindrical dielectric source tube which is open at one end. An axial magnetic field is applied to the plasma using one or more solenoids or a permanent magnet source. The magnetic field is usually applied such that it is constant throughout the length of the source tube, after which the field diverges. The plasma couples with the imposed magnetic field, generating internal field structures, which can be used to regulate both the power coupling and the rate at which the plasma diffuses out of the source tube. In this study, the thruster performance is measured directly, thus providing missions designers with accurate performance data which can be used to assess applicability of the technology to future missions. A re-configurable lab prototype thruster was constructed and a pendulum type thrust balance was developed in order to make direct measurements of the thrust produced by the Surrey Space Centre (SSC) RFPT. The balance has been developed to allow mounting of the thruster together with the necessary RF and DC electrical feeds as well as the propellant feeds and incorporates sensors which allow measurements to be made in an RF plasma environment. A low magnetic field mode of RFPT operation was investigated in order to assess whether this mode of operation may be able to provide performance increases at reduced imposed magnetic fields (< 20 mT), which could enable the serious consideration of this technology for future flight opportunities. The lowered magnetic fields used here may reduce the risk of interference with spacecraft subsystems and perturbation to the spacecraft orbit, when compared to many of the proposed plasma thrusters which use fields in excess of 40 mT. Direct thrust measurements of an RFPT operating in a low field mode are presented as a function of the propellant flow, RF power and for two source tube lengths. The thrust is shown to peak at a field strength, B_0, which is demonstrated to vary with RF power and propellant flow. The peaks are also shown to correspond generally to peaks in the source plasma density, plasma potential and in some cases to exhaust ion beam current. Ion energy distribution function measurements show that strong beams are not present in thruster configurations which use a 170 mm length source tube but are shown to increase in strength when using a shorter 85 mm length tube. The low field mode is shown to generally provide performance increases over the non-magnetised case by a factor of 4. Low field mode thrust measurements using the shorter 85 mm source tube and matching double saddle antenna revealed enhanced peak performance gains over the 170 mm length case, resulting in an increase of the thrust efficiency by up to a factor of 15. The performance of the RFPT operating in this configuration is shown to produce enhanced or equivalent performance, when compared to similar state of the art configurations but at generally lower imposed magnetic fields. This particular optimisation may make possible a first flight opportunity for the RFPT as weak magnetic fields may be supplied easily by electromagnets. Electromagnets can be easily deactivated or field reversed to avoid interference with spacecraft subsystems and orbital parameters unlike permanent magnets which may be required to generate higher magnetic fields. Operation of the RFPT in the low field mode with an 85~mm source has also revealed new low field mode behaviour compared to the 170 mm case, producing sudden, large reductions in the performance of the thruster for imposed fields beyond B_0 which are shown to correspond to drops in source plasma density, plasma resistance and exhaust beam current.
32
Hodge, James W. "A comparison between power line noise level field measurements and man-made radio noise prediction curves in the high frequency radio band." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1995. http://handle.dtic.mil/100.2/ADA306572.
Full text
33
Overstreet, William Patton. "VHF bipolar transistor power amplifiers: measurement, modeling, and design." Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/71166.
Full textAbstract:
Widely used design techniques for radio frequency power amplifiers yield results which are approximate; the initial design is usually refined by applying trial-and-error procedures in the laboratory. More accurate design techniques are complicated in their application and have not gained acceptance by practicing engineers. A new design technique for VHF linear power amplifiers using bipolar junction transistors is presented in this report. This design technique is simple in its application but yields accurate results.
The design technique is based upon a transistor model which is simple enough to be useful for design, but which is sufficiently accurate to predict performance at high frequencies. Additionally, the model yields insight into many of the processes which take place within the typical RF power transistor. The fundamental aspect of the model is the inclusion of charge storage within the transistor base. This charge storage effect gives rise to a nearly sinusoidal collector current waveform, even in a transistor which ostensibly is biased for class B or nonsaturating class C operation.
Methods of predicting transistor input and output impedances are presented. A number of other topics related to power amplifier measurement and design are also included. A unique measurement approach which is ideally suited for use with power amplifiers is discussed. This measurement approach is a hybrid of the common S-parameter measurement technique and the "load-pull" procedure. Practical considerations such as amplifier stability, bias network design, and matching network topology are also included in the report.Ph. D.
34
Andrews, Mark Joseph. "Design Considerations for 500-2000 MHz Ultra-Wideband Radiometric Measurements." The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1618312655065238.
Full text
35
Somasundaram, Meena Sivalingam. "Pulsed power and load-pull measurements for microwave transistors." [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0003293.
Full text
36
Hussaini, Abubakar S. "Energy efficient radio frequency system design for mobile WiMax applications. Modelling, optimisation and measurement of radio frequency power amplifier covering WiMax bandwidth based on the combination of class AB, class B, and C operations." Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/5749.
Full textAbstract:
In today´s digital world, information and communication technology accounts for 3%
and 2% of the global power consumption and CO2 emissions respectively. This
alarming figure is on an upward trend, as future telecommunications systems and
handsets will become even more power hungry since new services with higher
bandwidth requirements emerge as part of the so called ¿future internet¿ paradigm. In
addition, the mobile handset industry is tightly coupled to the consumer need for more
sophisticated handsets with greater battery lifetime. If we cannot make any significant
step to reducing the energy gap between the power hungry requirements of future
handsets, and what battery technology can deliver, then market penetration for 4G
handsets can be at risk. Therefore, energy conservation must be a design objective at the
forefront of any system design from the network layer, to the physical and the
microelectronic counterparts. In fact, the energy distribution of a handset device is
dominated by the energy consumption of the RF hardware, and in particular the power
amplifier design. Power amplifier design is a traditional topic that addresses the design
challenge of how to obtain a trade-off between linearity and efficiency in order to avoid
the introduction of signal distortion, whilst making best use of the available power
resources for amplification. However, the present work goes beyond this by
investigating a new line of amplifiers that address the green initiatives, namely green
power amplifiers. This research work explores how to use the Doherty technique to
promote efficiency enhancement and thus energy saving. Five different topologies of
RF power amplifiers have been designed with custom-made signal splitters. The design
core of the Doherty technique is based on the combination of a class B, class AB and a
class C power amplifier working in synergy; which includes 90-degree 2-way power
splitter at the input, quarter wavelength transformer at the output, and a new output
power combiner. The frequency range for the amplifiers was designed to operate in the
3.4 - 3.6 GHz frequency band of Europe mobile WiMAX. The experimental results
show that 30dBm output power can be achieved with 67% power added efficiency
(PAE) for the user terminal, and 45dBm with 66% power added efficiency (PAE) for
base stations which marks a 14% and 11% respective improvement over current stateof-
the-art, while meeting the power output requirements for mobile WiMAX
applications.
37
Hussaini, Abubakar Sadiq. "Energy efficient radio frequency system design for mobile WiMax applications : modelling, optimisation and measurement of radio frequency power amplifier covering WiMax bandwidth based on the combination of class AB, class B, and C operations." Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/5749.
Full textAbstract:
In today's digital world, information and communication technology accounts for 3% and 2% of the global power consumption and CO2 emissions respectively. This alarming figure is on an upward trend, as future telecommunications systems and handsets will become even more power hungry since new services with higher bandwidth requirements emerge as part of the so called 'future internet' paradigm. In addition, the mobile handset industry is tightly coupled to the consumer need for more sophisticated handsets with greater battery lifetime. If we cannot make any significant step to reducing the energy gap between the power hungry requirements of future handsets, and what battery technology can deliver, then market penetration for 4G handsets can be at risk. Therefore, energy conservation must be a design objective at the forefront of any system design from the network layer, to the physical and the microelectronic counterparts. In fact, the energy distribution of a handset device is dominated by the energy consumption of the RF hardware, and in particular the power amplifier design. Power amplifier design is a traditional topic that addresses the design challenge of how to obtain a trade-off between linearity and efficiency in order to avoid the introduction of signal distortion, whilst making best use of the available power resources for amplification. However, the present work goes beyond this by investigating a new line of amplifiers that address the green initiatives, namely green power amplifiers. This research work explores how to use the Doherty technique to promote efficiency enhancement and thus energy saving. Five different topologies of RF power amplifiers have been designed with custom-made signal splitters. The design core of the Doherty technique is based on the combination of a class B, class AB and a class C power amplifier working in synergy; which includes 90-degree 2-way power splitter at the input, quarter wavelength transformer at the output, and a new output power combiner. The frequency range for the amplifiers was designed to operate in the 3.4 - 3.6 GHz frequency band of Europe mobile WiMAX. The experimental results show that 30dBm output power can be achieved with 67% power added efficiency (PAE) for the user terminal, and 45dBm with 66% power added efficiency (PAE) for base stations which marks a 14% and 11% respective improvement over current stateof- the-art, while meeting the power output requirements for mobile WiMAX applications.
38
Wiid, P. Gideon. "Lightning protection and radio frequency interference mitigation for the Karoo Array Telescope." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4009.
Full textAbstract:
Thesis (PhD (Electrical and Electronic Engineering))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: South Africa and Australia are now the two remaining countries bidding for the Square Kilometre Array (SKA), the biggest and most sensitive project ever undertaken in radio astronomy. The South African SKA is demonstrating its technology capabilities through the Karoo Array Telescope (KAT or MeerKAT). The development of KAT is taking place in stages to optimise design and minimise risks at each stage. An array of seven 12 m antennas will be complete by the end of 2009, called KAT-7. The following phase will see the construction of MeerKAT, which will lead to eighty arrayed dishes. Lightning and RFI studies for KAT-7 are the focus of this dissertation. Due to the extent and complexity of the South African demonstrator project, these studies have largely been conducted on a single structure. Parameters for the dish antenna and pedestal design changed throughout their development. To be effective, the doctoral research had to track these changes appropriately. A Method of Moments frequency domain computational electromagnetic code, FEKO, is used throughout the study. The consequences of direct and indirect lightning strikes are examined for the KAT-7 structure. Important FEKO model verification is achieved through measurement of physical scale models in an anechoic chamber. The microwave simulation code, CST, gives direct comparison of FEKO results by using a finite volume time domain method of calculation. Using frequency domain analysis on these models, the lightning down conductor design over the dish antenna bearings is optimised with cost-effectiveness as one driving parameter. RFI coupling levels for different designs are compared to each other to identify areas requiring RFI mitigation. Analysis of resonances enables evaluation of the mitigation at frequencies sensitive to radio astronomy. A Sommerfeld integral ground plane is used together with the computational model to investigate the use of the concrete foundation steel reinforcing as part of the lightning earthing electrode system. Different interconnections of the steel reinforcing elements are critically evaluated. The KAT-7 design incorporated clear lightning protection and RFI mitigation policies derived from recommendations contained within this dissertation.
AFRIKAANSE OPSOMMING: Suid-Afrika en Australie is nou die oorblywende twee lande wat bie vir die Vierkante Kilometer Reeks (SKA), die grootste en mees sensitiewe projek nog ooit in radio astronomie onderneem. Die Suid Afrikaanse SKA demonstreer sy tegnologiese bekwaamheid met die Karoo Reeks Teleskoop (KAT of MeerKAT). Die ontwikkeling van KAT vind plaas in fases om die ontwerp te optimaliseer en risikos te minimaliseer met elke fase. ’n Reeks van sewe 12 m antennas, genaamd KAT-7, sal teen die einde van 2009 klaar wees. Die volgende fase behels die konstruksie van MeerKAT, wat sal lei tot ’n tagtig-skottel reeks. Die fokus van hierdie proefskrif hanteer weerlig en radiofrekwensie steurings (RFS) vir KAT-7. As gevolg van die omvang en kompleksiteit van die Suid-Afrikaanse demonstreerder projek, is die studies hoofsaaklik op een struktuur gedoen. Parameters vir die antenna-skottel en -voetstuk ontwerp het met hul ontwikkeling deurgaans verander. Om effektief te wees, moes die doktorale navorsing hierdie veranderinge toepaslik volg. ’n Metode-van-Momente frekwensiedomein rekenaar elektromagnetiese kode, FEKO, is deurgaans met die studie gebruik. Die gevolge van direkte en indirekte weerligslae vir die KAT-7 struktuur is ondersoek. Belangrike FEKO model bevestiging is bereik met metings van skaalmodelle in ’n anego¨ıse kamer. Die mikrogolf-simulasie kode, CST, gee ’n direkte vergelyking met die FEKO resultate deur ’n eindige-volume-tyd-domein metode van berekening te gebruik. Met behulp van frekwensiedomein analise van hierdie modelle, is die weerligafleierontwerp oor die antenna-skottel laers ge-optimaliseer, met koste-effektiwiteit as een van die drywingsparameters. RFS koppelingsvlakke vir onderskeie ontwerpe is teen mekaar opgeweeg om areas te identifiseer wat RFS tempering benodig. Analise van resonansies stel die evaluering van die tempering in staat teen frekwensies wat sensitief is vir radio astronomie. ’n Sommerfeld integrale grondvlak word saam met die rekenaarmodel gebruik om die insluiting van die beton se staalversterking as deel van die aardingselektrodestelsel te ondersoek. Verskillende bindmetodes van die onderlinge staalversterkingselemente word krities ge¨evalueer. Die KAT-7 ontwerp inkorporeer duidelike weerligbeveiligings- en RFS temperingstrategie ¨e, komende van aanbevelings in hierdie proefskrif omskryf
39
Pamuk, Gokhan. "Design And Realization Of Broadband Instantaneous Frequency Discriminator." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/3/12612044/index.pdf.
Full textAbstract:
In this thesis, RF sections of a multi tier instantaneous frequency measurement (IFM) receiver which can operate in 2 &ndash18 GHz frequency band is designed, simulated and partially realized. The designed structure uses one coarse tier, three medium tiers and one fine tier for frequency discrimination. A novel reflective phase shifting technique is developed which enables the design of very wideband phase shifters using stepped cascaded transmission lines. Compared to the classical phase shifters using coupled transmission lines, the new approach came out to be much easier to design and fabricate with much better responses. This phase shifting technique is used in coarse and medium tiers. In fine frequency measurement tier, I/Q discriminator approach is used because reflective phase shifters would necessitate unacceptably long delay lines. Two I/Q discriminators are designed and fabricated using Lange directional couplers that operate in 2-6 GHz and 6-18 GHz, resulting in satisfactory response. Additionally, 6 GHz HP and 6 GHz LP distributed filters are designed and fabricated to be used for these I/Q discriminators in fine tier. In order to eliminate possible ambiguities in coarse tier, a distributed element LP-HP diplexer with 10 GHz crossover frequency is designed and fabricated successfully to be used for splitting the frequency spectrum into 2-10 GHz and 10-18 GHz to ease the design and realization problems. Three power dividers operating in the ranges 2-18 GHz, 2-6 GHz and 6-18 GHz are designed for splitting incoming signals into different branches. All of these dividers are also fabricated with satisfactory response. The fabricated components are all compact and highly reproducible. The designed IFM can tolerate 48 degrees phase margin for resolving ambiguity in the tiers while special precautions are taken in fine tier to help ambiguity resolving process also. The resulting IFM provides a frequency resolution below 1 MHz in case of using an 8-bit sampler with a frequency accuracy of 0.28 MHz rms for 0 dB input SNR and 20 MHz video bandwidth.
40
Oliver, Matthew. "Density, temperature and magnetic field measurements in low density plasmas." Thesis, University of Oxford, 2018. http://ora.ox.ac.uk/objects/uuid:df217453-1e10-4684-beb7-83c1bcecf285.
Full textAbstract:
Low density plasmas are found throughout the known universe. Therefore, accurate diagnostic methods have implications for our understanding of a variety of topics, ranging from star formation to the semi conductor industry. Low density plasmas are ubiquitous in the material processing industry. However, measurements of the electron temperature and density, two of the most fundamental plasma properties, are not straightforward. In the laboratory, we create a low density, radio frequency, helium plasma with a bi-Maxwellian electron distribution, similar to those found in the semiconductor processing industry. We use optical emission spectroscopy to perform a non invasive measurement of the plasma conditions. We compare this to measurements obtained using a Langmuir probe, a commonly used invasive diagnostic. The optical emission spectroscopy is found to be insensitive to electron density but good agreement is found between the two techniques for values of the temperature of the hot electron component of the bi-Maxwellian. Plasmas created with high-intensity lasers are able to recreate conditions similar to those found during astrophysical events. This development has led to these condi- tions being explored in laboratories around the world. An experiment was performed at the Rutherford Appleton Laboratory in Didcot, UK, investigating the properties of supersonic turbulent jets. For the first time a magneto-optic probe was used to measure the magnetic field in a low-density supersonic turbulent plasma. The results were compared to measurements taken using a magnetic-induction probe. Good agreement was found between measurements of the magnetic field strength within the plasma; however, the magnetic power spectra differ. We attribute this to the dif- ference in integration length between the two measurements. Statistical properties of the velocity field are inferred from the magnetic field measurements, which compare favourably to astrophysical observations and hydrodynamic simulations.
41
Ali, Ammar H. A. "Design and Implementation of Radio Frequency Power Feeding Networks for Antenna Array Applications: Simulation and Measurements of Multiport, Equal and Unequal, Fixed and Reconfigurable Radio Frequency Power Feeding Networks for Narrow and Ultra-Wideband Applications." Thesis, University of Bradford, 2018. http://hdl.handle.net/10454/17447.
Full textAbstract:
Power dividers are vital components and widely used in radio technology, such
as antenna arrays, power amplifiers, multiplexers and mixers. A good example is
the well-known Wilkinson power divider with its distinctive feeding network
characteristics. A comprehensive review indicated that limited research is carried
out in the area of planar multiport and reconfigurable power dividers in terms of
the power levels between output ports.
The main objectives of this work were to develop a small size power divider, a
planer multi-output ports power divider and a power divider with a reconfigurable
power division ratio. These power dividers were designed to operate over either
an ultra-wideband frequency (3.1-10.6 GHz) or WLAN bands (2.4 or 5.2 GHz).
A novel multi-layered topology solved the complexity of interconnecting isolation
resistors by introducing an additional layer below the ground layer. The prototype
was fabricated and tested to validate the results. The measurements and
simulation were in good agreement.
Finally, a novel uniplanar power divider with reconfigurable output power level
difference was developed. The configurability feature was achieved by tuning the
quarter wave transformer using one varactor diode. The power divider was
applied to improve a full duplex system cancellation performance at the receiver
element caused by interference from in-site transmitting antennas.
This study investigated fixed power dividers, multi-output power dividers and
reconfigurable power dividers. The measurements validated by the simulation
results and applications proved the designed power dividers could be used in
practical applications.Higher Committee for Education Development (HCED), Iraq
42
Joshi, Sujay S. "Multi-Target Tracking via Nonlinear Least Squares Using Doppler Measurements from a Passive Radar System." Thesis, Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14576.
Full textAbstract:
A passive radar systems opportunistic ability to exploit ambient radio signal reflections makes it ideal for covert target tracking. This strategy, referred to as passive covert radar (PCR) or passive coherent location (PCL), typically exploits FM radio or television signals from powerful local transmitters. In addition to covertness, the absence of a dedicated transmitter helps reduce costs and overall system complexity. While a variety of measurements can be used to estimate a targets position and velocity, such as time difference of arrival (TDOA) and direction of arrival (DOA), this thesis focuses on using only Doppler shift measurements to estimate a targets state.
The work presented in this thesis examines the use of Doppler shift measurements from multiple receivers to solve the target tracking and association problem. A nonlinear least squares error (NLSE) estimation technique, called the Levenberg-Marquardt (L-M) algorithm, is used to determine a targets state (position, velocity) from these Doppler shift measurements. More than one target state can potentially produce identical Doppler shift profiles. In a single-receiver, single-target scenario, it is shown that three additional ghost targets caused by symmetry produce the same Doppler shift response. These ghosts may make state estimation impossible if receive antennas are not physically positioned to block out ghost targets. While the NLSE technique tends to give an accurate solution in one quadrant, three other solutions will symmetrically exist in each of the remaining three quadrants. The addition of either another receiver or another measurement (such as DOA) is needed to break this quadrant ambiguity. This thesis considers adding multiple receivers to accurately associate and track multiple targets. Two target association methods (sequential and simultaneous) are developed, and their computational requirements and accuracy are compared. A grid-aided L-M search technique is investigated in an attempt to provide a better initial target state guess to these association and tracking algorithms.
The analysis and simulation results suggest it is feasible to perform multi-target association and tracking using Doppler shift as the sole measurement. Both of the proposed methods gave optimal target association and converged to reasonably accurate state estimates in most of the Monte Carlo runs.
43
Oxtoby, Neil Paul. "Keeping it real': A Quantum Trajectory Approach to Realistic Measurement of Solid-State Quantum Systems." Thesis, Griffith University, 2007. http://hdl.handle.net/10072/365770.
Full textAbstract:
To obtain information about a system of interest a measurement has to be made. In experiments that probe the quantum nature of our world, the system itself is, in general, necessarily affected by the act of measurement. If the system is weakly coupled to its bath and the dynamics are such that information concerning the system is spread throughout the many degrees of freedom of the bath, and the bath is being measured then a stochastic master equation for the conditioned state of the system can be found. This is termed a quantum trajectory equation. Realistic detectors are not perfect. Information is lost in the conversion to a signal that the observer can use. This loss may occur in the detector itself, in the circuit containing the detector (described by a response time and electronic noise) or at the circuit output (electronic output noise). In order to obtain a true quantum trajectory for the experiment, the observer must condition the state of the quantum system on results that are available in the laboratory rather than on the microscopic events considered previously in quantum trajectories. A method for treating this was first proposed by Warszawski, Wiseman and Mabuchi [Phys. Rev. A 65, 023802 (2002)], in which the quantum system is embedded within a supersystem that also contains the state of the detector. They applied their theory to photodetectors of various sorts. Warszawski has also done the preliminary work on applying this theory to detecting the state of a pair of quantum dots using a SET (single-electron transistor) [MSc. Thesis, Griffith University (2001)]. The resulting theory is termed 'realistic' quantum trajectory theory.
In this thesis, the approach of Warszawski, et al.is applied to various solidstate readout devices. These include the SET, the QPC (quantum point contact), and the RF-QPC (radio-frequency QPC). Numerically obtained realistic quantum trajectories for the QPC agree with heuristic results. In particular, in certain limits, the realistic quantum trajectories can take on the appearance of ideal quantum trajectories. This thesis also resolves a problem in solid-state continuous quantum measurement theory by deriving a quantum trajectory model for a SET-monitored charge qubit, that guarantees physically meaningful qubit states. The particular limit necessary to achieve this is discussed, and the SET measurement quality is analysed using techniques borrowed from quantum optics. Conditions for which the SET can approach operation at the limit allowed by quantum mechanics are given. This is also done for the QPC, for which the results agree with previous work.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Science
Full Text
44
Tiesler, Hanne [Verfasser], Tobias [Akademischer Betreuer] Preußer, and Christof [Akademischer Betreuer] Büskens. "Identification of Material Parameters from Temperature Measurements in Radio Frequency Ablation / Hanne Tiesler. Gutachter: Tobias Preußer ; Christof Büskens. Betreuer: Tobias Preußer." Bremen : Staats- und Universitätsbibliothek Bremen, 2011. http://d-nb.info/107189823X/34.
Full text
45
Zemba, Michael J. "Site Characterization of Phase Instability via Interferometer Measurement." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1383565461.
Full text
46
COSOLI, GLORIA. "Study and development of a novel radio frequency electromedical device for the treatment of peri-implantitis: experimental performance analysis, modelling of the electromagnetic interaction with tissues and in vitro and in vivo evaluation." Doctoral thesis, Università Politecnica delle Marche, 2017. http://hdl.handle.net/11566/245278.
Full textAbstract:
La peri-implantite (PI) è una grave patologia che interessa tessuti peri-implantari molli e duri. Ad oggi, la prevenzione è l’unico mezzo per contrastarla.
Recentemente, è stata sperimentata una terapia basata sulla somministrazione di corrente elettrica a radio frequenza (successo: 81%). Il trattamento è stato simulato numericamente, fornendo le distribuzioni di corrente (EC) e campo elettrico (EF) nei tessuti: l’effetto anti-infiammatorio è attribuibile alla EC, quello di rigenerazione ossea al EF.
Sono state considerate le misure di bioimpedenza (BM) per individuare le infiammazioni; numericamente si sono osservati cambiamenti nel modulo di impedenza del 4-20% (secondo diversi parametri), anche più alti sperimentalmente (35% infiammazione, 56% PI). Le BM permettono quindi di identificare il tessuto da trattare.
Per la ripetibilità, sono state considerate radici di denti naturali, numericamente e sperimentalmente; l’ordine di grandezza è lo stesso (qualche kΩ), anche se ci sono differenze legate alle condizioni di misura. La variabilità intra-soggetto è il 10% in uno stesso giorno, fino al 26% in giorni diversi; quella inter-soggetto è più alta.
La sicurezza elettrica è stata attentamente esaminata e si sono individuate le direttive applicabili (IEC 60601-1, 60601-1-2 and 60601-2-2).
Sono stati fatti test in vitro per valutare l’effetto della terapia sulla vitalità cellulare: non c’è un significativo aumento della necrosi (vitalità: 85% test, 94% controlli), l’effetto negativo principale è l’apoptosi.
Sono stati numericamente indagati possibili effetti termici: non sono stati individuati riscaldamenti nocivi dei tessuti.
Si è progettato un nuovo dispositivo (PeriCare®) per trattare la PI, con parti diagnostica (BM) e terapeutica. Si stanno progettando elettrodi specifici e realizzando il prototipo. Si sta compilando il fascicolo tecnico e pianificando i test di conformità, in vista della certificazione. Il dispositivo medico dovrebbe entrare nel mercato entro l’anno.Peri-implantitis is a severe disease affecting hard and soft peri-implant tissues. At present, prevention is the only means to contrast it. Recently, a therapy based on the administration of radio frequency electric current was experimented (success rate: 81%). The treatment was numerically simulated, providing the electric current (EC) and field (EF) distributions in peri-implant tissues: the anti-inflammatory effect can be associated to EC, the bone regeneration to the EF. Bioimpedance measurements (BM) were investigated to detect inflammation; changes in the measured impedance modulus are equal to 4-20% (depending on different parameters) from numerical results, also more evident experimentally (35% inflammation, 56% peri-implantitis). So, BM could allow to detect the tissue to be treated. To evaluate the repeatability, natural tooth roots were numerically and experimentally measured; the order of magnitude is the same (some kΩ), even if there are differences probably due to the measurement conditions. Intra-subject variability was of 10% in the same day, but up to 26% in different days; inter-subject variability was higher. The electrical safety was accurately taken into account. The applicable directives were individuated (IEC 60601-1, 60601-1-2 and 60601-2-2). In vitro tests were carried out to evaluate the effect of the therapy on cell vitality: there is not a significant increase in necrosis (vitality: 85% tests, 94% controls), the main negative effect is apoptosis. Possible thermal effects were numerically investigated: no dangerous tissue heating was observed. A new device for the peri-implantitis treatment, PeriCare®, was designed, with diagnostic (BM) and therapeutic parts. Proper electrodes are being designed and the prototype is being realized. The technical file is being compiled and the conformity verification tests are being planned towards the certification process. Hopefully, the medical device will be placed into the market within this year.
47
Kukshya, Vikas. "Wideband Terrestrial Path Loss Measurement Results For Characterization of Pico-cell Radio Links at 38 GHz and 60 GHz Bands of Frequencies." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/33669.
Full textAbstract:
The advent of Internet based digital services, and bandwidth-intensive business and personal applications has necessitated deployment of broadband network access technologies. Research analysts project that the U.S. market for broadband wireless networking will grow to nearly $2 billion by 2004 and Local Multipoint Distribution Services (LMDS) have enormous potential to emerge as the most reliable and cost-effective solution. However, in order to design and deploy LMDS systems, it is vital for system designers to be able to predict the behavior of mm-waves (28, 38 and 60GHz) during different weather conditions, especially rain. This research attempts to characterize the performance of pico-cell scenario broadband wireless channels by measuring path loss statistics during different weather conditions.
Hardware and software components of a wideband direct-sequence spread spectrum (DSS) channel sounding system, used extensively throughout measurement campaigns, are discussed in detail in this dissertation. The measurement plan comprehensively describes the methodology, logistics, equipment setup, and calibration procedures for propagation measurement campaigns.
Power Delay Profile (PDP) snapshots recorded during measurement campaigns are thoroughly analyzed using the 'Channel Imaging Analysis Suite' and Path Loss as well as Rain Attenuation statistics, calculated from recorded PDP data files, are classified and tabulated on the basis of measurement locations, propagation frequencies and antenna polarizations. Path Loss Exponent values are also calculated and Rain Attenuation statistics are compared with popular rain models. Results from Frequency Diversity measurement campaigns are also presented.Master of Science
48
Reissig, Alexander. "Evaluation of on-line cell viability and L-lactate measurements in soft sensor for mammalian cell cultures." Thesis, Linköpings universitet, Teknisk biologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-112918.
Full textAbstract:
Increasing demand on more effective cell culture reactors has driven optimization works to increase output of products. This has led to development of soft sensors that uses mathematical formulas to increase the available information for the parameters during runs. In the project two parameters was evaluated for use in such a soft sensor, viability by measuring on-line capacitance with Aber probe and L-lactate production using BioSenz apparatus. To determine how well these could be used both were used on batch reactors measuring on a mouse-mouse B cell hybridoma culture which produced IgG1. On-line measurements were performed by probes which measured directly on the cell suspension or withdrew sterile sample from the reactor. Measuring viability gave results with low error, which can be concluded to the variation in reference cell count, but it could not be determined if measuring L-lactate production with BioSenz works in reactors of this size. More work needs to be done on other types of reactors, like fed-batch or perfusion, or lower working volumes.
49
Ghazaany, Tahereh S. "Design and implementation of adaptive baseband predistorter for OFDM nonlinear transmitter. Simulation and measurement of OFDM transmitter in presence of RF high power amplifier nonlinear distortion and the development of adaptive digital predistorters based on Hammerstein approach." Thesis, University of Bradford, 2011. http://hdl.handle.net/10454/5680.
Full textAbstract:
The objective of this research work is to investigate, design and measurement of a digital
predistortion linearizer that is able to compensate the dynamic nonlinear distortion of a High
Power Amplifier (PA). The effectiveness of the proposed baseband predistorter (PD) on the
performance of a WLAN OFDM transmitter utilizing a nonlinear PA with memory effect is
observed and discussed. For this purpose, a 10W Class-A/B power amplifier with a gain of 22
dB, operated over the 3.5 GHz frequency band was designed and implemented.
The proposed baseband PD is independent of the operating RF frequency and can be used in
multiband applications. Its operation is based on the Hammerstein system, taking into account
PA memory effect compensation, and demonstrates a noticeable improvement compared to
memoryless predistorters.
Different types of modelling procedures and linearizers were introduced and investigated, in
which accurate behavioural models of Radio Frequency (RF) PAs exhibiting linear and
nonlinear memory effects were presented and considered, based on the Wiener approach
employing a linear parametric estimation technique. Three new linear methods of parameter
estimation were investigated, with the aim of reducing the complexity of the required filtering
process in linear memory compensation. Moreover, an improved wiener model is represented to
include the nonlinear memory effect in the system. The validity of the PA modelling approaches
and predistortion techniques for compensation of nonlinearities of a PA were verified by several
tests and measurements. The approaches presented, based on the Wiener system, have the
capacity to deal with the existing trade-off between accuracy and convergence speed compared
to more computationally complex behavioural modelling algorithms considering memory
effects, such as those based on Volterra series and Neural Networks.
In addition, nonlinear and linear crosstalks introduced by the power amplifier nonlinear
behaviour and antennas mutual coupling due to the compact size of a MIMO OFDM transmitter
have been investigated.
50
Hlaváč, Štěpán. "Vysokofrekvenční měřič výkonu." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-220258.
Full textAbstract:
This master’s thesis describes various principles of measurement of electromagnetic waves in a free space and on a line. Used sensors and their real parameters are given for every method. The analysis of protections of high-frequency inputs of measuring instruments is done here and the most suitable method and protections of input for realization are chosen. The analysis of design of secondary protection of high-frequency input is done in this project. The protection of input is realized and measured. The suitable method of measurement is chosen as well as the sensor for measurement of power. The block diagram and circuit diagram of the meter of power are designed. According to designed conception the measuring instrument for measurement of power is realized and its single qualities are measured during the realization. In the final part its precision is measured and the evaluation of results is done.