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Tesi sul tema "Microwave receivers"
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Banciu, Marian Gabriel Electrical Engineering & Telecommunications Faculty of Engineering UNSW. "Radio frequency and microwave design methods for mobile communications". Awarded by:University of New South Wales. School of Electrical Engineering and Telecommunications, 2003. http://handle.unsw.edu.au/1959.4/18814.
Testo completoAbstract (sommario):
The Global System for Mobile communications (GSM), which covers 54% of the world's mobile market, evolved into the General Packet Radio Service (GPRS). The thesis addresses interference suppression using new radio frequency (RF) and microwave design methods for GSM and GPRS. The overall outcome is interference reduction and enhanced network capacity, leading to superior quality of service (QoS) for wider area coverage. The main results can be summarized as follows * Design, manufacturing and characterisation measurements of new compact filters for GSM and GPRS base stations in order to reduce the out-of-band interference. It is shown that filters with novel microstrip resonators - dual mode filters and cross coupled filters - provide both a high degree of miniaturisation and narrow bandwidth. * Development of a new 3-D Finite-Difference Time-Domain (FDTD) design method for new microstrip filters. A non-homogeneous Perfectly Matched Layer (NH-PML) was implemented for Absorbing Boundary Conditions (ABC) to increase the accuracy of the FDTD method. Signal estimation techniques were developed to speed up FDTD computations. A novel design method based on neural networks (NN) and FDTD was implemented to reduce the total design time. * Investigation of High Temperature Superconductors (HTS) thin film resonators and antennas at microwave frequencies. High Q-factor HTS devices considerably enhance both the front-ends sensitivity and selectivity of wireless receivers. * Design, manufacturing and testing of radio frequency (RF) electronics for 16 elements GSM and GPRS Smart Antenna for multipath fading mitigation and for in-band interference including co-channel interference (CCI) suppression.
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Barrueto, González Ignacio Alberto Hugo. "Development of microwave devices for millimeter and sub-millimeter receivers". Tesis, Universidad de Chile, 2017. http://repositorio.uchile.cl/handle/2250/148315.
Testo completoAbstract (sommario):
Magíster en Ciencias de la Ingeniería, Mención EléctricaThe Atacama Large Millimeter/Submillimeter Array (ALMA) is one of the largest astronomical facilities in the world. Each of the 66 antenn as accommo dates ten ob servational band s, covering from 35-950 GHz. To extend the op erative lifesp an of ALMA, a conti nuous upgrade program is in place. Among other ob jectives, this program pursues the increase of bandwidth of the instruments and the need to complement ALMA with another observatories supp orting multi-pixel arrays. This thesis work is placed within two pro jects that attemp t to reach those goals. The first is th e ALMA Band-2+3 upgrade prop osal, that attempts to merge Bands 2 and 3 in a single receiver. The second one is the development of instrumentation for the CCAT-p Telescope, to be placed next to the site of ALMA, at Cerro Chajnantor. A heterodyne receiver is composed by the feed antennas which captures the radiation concentrated by the main dishes. Depending on the structure of the receiver, an orthomode transducer (OMT) separates the polarization in two orthogonal components. Subsequently the signal is mixed with a local oscillator signal in order to down-convert the original signal. More specifically, this thesis presents the design, construction and characterization of a turnstile OMT for ALMA Band 2+3 receiver and the study and design of a LO power distribution scheme for the CCAT-p Heterodyne Array Instrument. The OMT should comply with the stringent ALMA requirements set for all passive devices. A design was conceived to solve construction issues of a previous version. The measurements show that the OMT does comply with most of them. However, a disagreement between the simulations and measurements prompted us to determine the effective conductivity of milled waveguides at 15, 77 and 290 K. In order to do so, we characterized waveguide meanders. These results improved the agreement and could used on future design efforts. The LO power distribution of CHAI requires to deliver the LO signal to an 4 × 4 array, which will serve as a basic block for larger arrays configurations. The 4 × 4 array will be assembled out of 4 rows of 1× 4 pixels. The distribution must cover the 800-820 GHz band, the imbalance between power delivered to each mixer must be lower than −3 dB and the whole distribution must fit within a footprint of 40 × 40 mm^2. We have presented two designs based on coplanar waveguides (CPW) and waveguide technology, a balanced scheme based on hybrids and an imbalanced scheme based on Wilkinson power dividers. The balanced scheme required waveguides of considerable length, generating standing waves that created a considerable imbalance in the power distribution. The second scheme is an unequal power distribution that has a theoretically better performance but requires 3:1, 2:1 and 1:1 Wilkinson dividers. The simulations of 3D model of a CPW 3:1 Wilkinson shows that the actual model does not achieve the expected performance. However, further optimization promises an improvement in performance. In both projects we have demonstrated that careful design makes possible to obtain devices whose performance surpass the current state of the art.
Este trabajo ha sido parcialmente financiado por CONICYT a través de los proyectos FONDECYT 11151022 y BASAL PFB06
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Sylvester, William R. "Theory, design and implementation of a digital receiver for the Advanced Communications Technology Satellite (ACTS) beacons". Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-08182009-040444/.
Testo completoAbstract (sommario):
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992.1 ill. in back pocket. Vita. Abstract. Includes bibliographical references (leaves 224-228). Also available via the Internet.
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Nam, Sueng-Il. "Design of monolithic microwave and millimetre-wave transmitters and receivers for wireless applications". Thesis, King's College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.392126.
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Matinpour, Babak. "Design and development of compact and monolithic direct conversion receivers". Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/14991.
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Lee, Dong-Wook. "Extracting multiple frequencies from phase-only data". Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/15031.
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Berenguer, Sau Jordi. "Síntesis de frecuencias en microondas mediante sistemas PLL: aplicación a la recepción de señales emitidas por satélite hasta 30 GHz". Doctoral thesis, Universitat Politècnica de Catalunya, 1988. http://hdl.handle.net/10803/6898.
Testo completoAbstract (sommario):
La tesi estudia el problema de la síntesi de freqüències en les bandes de freqüències de microones i ones mil·limètriques, i la seva aplicació al disseny dels oscil·ladors locals d'un receptor coherent per a la recepció de les *radiobalises que a 12, 20 i 30 GHz emetia el satèl·lit Olympus de l'Agència Espacial Europea (ESA), amb la finalitat de caracteritzar el comportament radioelèctric de l'atmosfera a aquestes freqüències, a partir de mesures d'atenuació i transpolarització sobre aquests senyals de test, tot això dintre del marc d'un experiment de propagació (OPEX) propiciat per l'agència.La tesi s'ha centrat en l'estudi dels sistemes de síntesis de freqüències utilitzats habitualment, i especialment en els de síntesi indirecta de freqüència basats en sistemes Phase Locked Loop (PLL) a freqüències de microones ja que són la base sobre la qual s'han dissenyat i construït els prototips de multiplicadors de freqüència que s'han desenvolupat, capaços de sintetitzar senyals en bandes de mil·limètriques, que en el nostre cas s'han restringit al marge de 1 a 29 GHz.
Alguns dels multiplicadors fan ús de la detecció de fase harmònica, sistema que permet realitzar multiplicacions de freqüència d'índex imparell, evitant la utilització de divisors de freqüència en el llaç de realimentació del PLL.
La tesi s'estructura en quatre parts diferenciades. La primera, amb un caire eminentment teòric, s'ofereix a manera de revisió dels aspectes del soroll de fase i dels sistemes de síntesis de freqüències existents. La segona part aborda les qüestions derivades de la síntesi de freqüències en microones mitjançant PLL's, amb descripció dels components utilitzats, per a passar a tractar dels aspectes de disseny d'un receptor coherent, els seus requisits i aplicacions. En la tercera part es presenten els multiplicadors de freqüència realitzats, la seva descripció, esquema de blocs i resultats experimentals obtinguts. I finalment, en la quarta part s'inclouen una sèrie de realitzacions derivades de la utilització de sistemes PLL a freqüències de microones, amb sincronització per injecció del VCO al senyal de referència, en aplicacions de combinació de potència i de control electrònic de fase en sistemes phased-arrays amb elements actius.
La tesis estudia el problema de la síntesis de frecuencias en las bandas de frecuencias de microondas y ondas milimétricas, y su aplicación al diseño de los osciladores locales de un receptor coherente para la recepción de las radiobalizas que a 12, 20 y 30 GHz emitía el satélite Olympus de la Agencia Espacial Europea (ESA), con la finalidad de caracterizar el comportamiento radioeléctrico de la atmósfera a estas frecuencias, a partir de medidas de atenuación y transpolarización sobre esas señales de test, todo ello dentro del marco de un experimento de propagación (OPEX) propiciado por la agencia.
La tesis se ha centrado en el estudio de los sistemas de síntesis de frecuencias utilizados habitualmente, y en especial en los de síntesis indirecta de frecuencia basados en sistemas Phase Locked Loop (PLL) a frecuencias de microondas puesto que son la base sobre la que se sustentan los prototipos de multiplicadores de frecuencia que se han desarrollado, capaces de sintetizar señales en bandas milimétricas, que en nuestro caso se han restringido al margen de 1 a 29 GHz.
Algunos de los multiplicadores hacen uso de la detección de fase armónica, sistema que permite realizar multiplicaciones de frecuencia de índice impar, evitando el empleo de divisores de frecuencia en el lazo de realimentación del PLL.
La tesis se estructura en cuatro partes diferenciadas. La primera, con un cariz eminentemente teórico, se ofrece a modo de revisión del tema del ruido de fase y de los sistemas de síntesis de frecuencias existentes. La segunda parte aborda las cuestiones derivadas de la síntesis de frecuencias en microondas mediante PLL's, con descripción de los componentes utilizados, para pasar a tratar de los aspectos de diseño de un receptor coherente, sus requisitos y aplicaciones. En la tercera parte se presentan los multiplicadores de frecuencia realizados, su descripción, esquema de bloques y resultados experimentales obtenidos. Y por último, en la cuarta parte se incluyen una serie de realizaciones derivadas de la utilización de sistemas PLL a frecuencias de microondas, con sincronización por inyección del VCO a la señal de referencia, en aplicaciones de combinación de potencia y de control electrónico de fase en sistemas phased-arrays con elementos activos.
The thesis studies the problem of the synthesis of frequencies in the microwave and millimeter waves frequency bands, and its application to the design of the local oscillators of a coherent receiver for the reception of the radio beacons that to 12, 20 and 30 GHz emitted the satellite Olympus from the European Space Agency (ESA), with the aim of characterizing the radio behavior of the atmosphere at these frequencies, from measurements of attenuation and transpolarisation on those signals of test, all that in the framework of a propagation experiment (OPEX) favored by the agency.
The thesis has been focused on the study of the frequency synthesis systems, and especially on the indirect frequency synthesis systems based on Phase Locked Loops (PLL) at microwave frequencies, since they are the base on which the prototypes of frequency multipliers that they have been developed, capable of synthesizing signals in millimeter bands, are held that in our case they have restricted regardless of 1 to 29 GHz.
Some of the multipliers make use of the harmonic phase detection system that allows carrying out frequency multiplications of odd index, preventing the use of frequency dividers in the feedback loop of the PLL.
The thesis is structured in four differentiated parts. The first, with an eminently theoretical look, offers like revision of the subject of the phase noise and the methods of frequency synthesis. The second part tackles the questions derived from the synthesis of frequencies in microwaves through PLL's, with description of the used components, to pass to deal of the aspects of design of a coherent receiver, its requirements and applications. In the third part the frequency multipliers carried out, its description, schema of blocks and obtained experimental results are presented. And finally, in the fourth part a series of accomplishments are included phased-arrays derived of the use of systems PLL at frequencies of microwaves, with synchronization by injection of the VCO to the reference signal, in applications of power combination and of electronic phase control in systems with active elements.
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Ajaz, Haroon. "Study of fade and inter-fade durations in Ku- and Ka- band frequencies using OLYMPUS satellite beacons". Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-12042009-020112/.
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Laster, Jeff D. "Frequency scaling of rain attenuation on satellite links in the Ku/Ka-bands using OLYMPUS satellite data". Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06162009-063211/.
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Chitnis, Danial. "Single photon avalanche diodes for optical communications". Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:5fd582dd-8167-4fe4-88f8-871ba905ade1.
Testo completoAbstract (sommario):
In order to improve the sensitivity of an optical receiver, the gain and the collection area of the photo-detectors within the receiver should be increased. Detectors with internal gain such as avalanche photodiodes (APD) are usually used to increase the sensitivity of the receiver. One problem with APDs is the sensitivity of their gain to their bias voltage, which makes them challenging to be fabricated in a standard CMOS process due to variations in their gain. However, when an APD is biased over its breakdown voltage, it is sensitive to a single photon, hence, referred to as a single photon avalanche diodes (SPAD). The SPADs are photon-counting detectors, which are less sensitive to their bias voltage, and can be integrated with rest of the electronic circuitry that form an optical receiver. An avalanche diode requires dedicated circuits to be operated in the SPAD mode. These circuits make the diode insensitive to an incident photon for a duration that is known as deadtime. Unfortunately, The collection area of the PD, APD, and SPADs are limited to their capacitance. Hence, a large photo-detector leads to a larger capacitance, which reduces the bandwidth of the receiver. In this thesis, a photon counting optical receiver based on an array of SPADs is proposed which increases the collection area with a low output capacitance. The avalanche diode and peripheral circuits which operate and readout-out the SPAD array are fabricated in the commercially available UMC 0.18 μm CMOS process. Initially, the avalanche diode is tested and characterised. A high performance circuit is then designed and tested which is able to achieve short deadtimes up to 4 ns. Once the photon counting operation of the SPAD is verified, a numerical model is developed to investigate the influence of several factors, including the deadtime, on the performance of the photon-counting detector in a communication link. Based on the simulation results, which show the advantages of an array over a single detector, a prototype detector array of 64 asynchronous SPADs is designed and tested. This array uses a high-speed readout mechanism which is inspired by the current steering digital-to-analogue converters. Bit error ratio tests (BERT) verify the photon counting capability of the proposed detector, and a bit error rate of 1E-3 has been achieved at data rate of 100 Mbps. In addition, the array of SPAD is compatible with a front-end of conventional optical receiver which uses a photodiode as a photo detector.
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Varin, Andre Carleton University Dissertation Engineering Electrical. "A wideband microwave surveillance receiver". Ottawa, 1987.
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Huang, Heng, Justin Legarsky e Qiang Lei. "A DESIGN OF A DIGITALLY CONTROLLABLE WIDEBAND MICROWAVE RECEIVER". International Foundation for Telemetering, 2006. http://hdl.handle.net/10150/603935.
Testo completoAbstract (sommario):
ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, CaliforniaRadar echo sounders provide a safe, inexpensive and effective means of obtaining ice sheet thickness. As the roughness of ice surface/subsurface depends on the radio wavelength, wideband radar sensors can provide flexibility for ice thickness measurement under areas with various surface conditions. This paper presents the design of a digitally controllable wideband microwave receiver for a potential radar sounding system. Its radio frequency (RF) frequency ranges from 50 to 500 MHz, while the intermediate frequency (IF) bandwidth is 20 MHz. The receiver provides eight channels for different RF band choices, as well as a number of convenient gain settings. Testing measurements have also been conducted to verify the design requirements.
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Alsolami, Ibrahim. "Visible light communications with single-photon avalanche diodes". Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:744eeb47-8bb6-4776-8b8f-f7b6374d89bd.
Testo completoAbstract (sommario):
This thesis explores the use of single-photon avalanche diodes (SPADs) for visible light communications (VLC). The high sensitivity of SPADs can potentially enhance the performance of VLC receivers. However, a SPAD-based system has challenges that need to be addressed before it can be considered as a viable option for VLC. The first challenge is the susceptibility of SPAD-based receivers to variations in ambient light. The high sensitivity of SPADs is advantageous for signal detection, but also makes SPADs vulnerable to variations in ambient light. In this thesis, the performance of a SPAD-based receiver is investigated under changing lighting conditions. Analytical expressions to quantify performance are derived, and an experiment is conducted to gain further understanding of system performance. It is shown that a SPAD-based receiver is highly sensitive to illumination changes when on-off keying (OOK) is employed, and that pulse-position modulation (PPM) is a preferred modulation scheme as it is more robust. The second challenge is broadcasting to SPAD-based receivers with different capabilities. A traditional broadcasting scheme is time-sharing, whereby a transmitter sends data to receivers in an alternating manner. Broadcasting to SPAD-based receivers is challenging as receivers may have diverse capabilities. In this thesis, a new multiresolution modulation scheme is proposed, which can potentially improve system performance over the traditional timesharing approach. The performance of the proposed scheme is analyzed, and a proof-of-concept experiment is performed to demonstrate its viability.
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Netshifhire, Vhudilangi Patrick. "The design and implementation of microwave receiver front end components". Thesis, Stellenbosch : Stellenbosch University, 2005. http://hdl.handle.net/10019.1/50473.
Testo completoAbstract (sommario):
Thesis (MScEng)--Stellenbosch University, 2005.ENGLISH ABSTRACT: Different types of RF and Microwave receiver systems architectures are investigated. The superheterodyne receiver characteristics are studied qualitatively. A three components system (LNA, Mixer and VeO) is selected and the components are first measured individually, and then measured as a single system. A mono filar axial mode helix antenna is designed, simulated using FEKO and constructed. A narrow band interdigital bandpass filter is designed using the capacitance network and its transformation, and it is simulated using two different simulation packages, eST Microwave Studio and AWR Microwave Office. Two filter prototypes are fabricated using cylindrical rods. An open circuited microstrip resonator oscillator is designed and implemented through the negative resistance method. Its performance is verified using the harmonic balance simulator in AWR MWO. A single balanced mixer is designed and implemented using 1800 hybrid junction (rat-race) and it is also fabricated using microstrip transmission line technology. All designed components performed well in comparison to their predicted performance. The LNA and three of the designed components (Filter, Oscillator and a Mixer) are connected together and characterized as a single four block system. The system performed well except for the IF signal which shift to a lower frequency due to oscillator load pulling.
AFRIKAANSE OPSOMMING: Die argitektuur van verskeie RF en Mikrogolf ontvanger stelsels word ondersoek. Die "superheterodyne" ontvanger eienskappe is kwalitatief bestudeer. 'n Stelsel wat uit drie komponente bestaan (LNA, Menger en VeO) is bestudeer. Die individuele komponente is eers gemeet en daarna die stelsel as 'n eenheid. 'n "Mono filar" aksiale modus heliks antenna is ontwerp, gesimuleer met FEKO en gebou. Verder is 'n nouband inter-digitale banddeurlaat filter ontwerp met behulp van die kapasitiewe network metode en sy transformasie. Hierdie ontwerp is gesimuleer deur van twee verskillende sagteware pakette gebruik te maak, naamlik eST Microwave Studio en AWR Microwave Office. Twee filter prototiepes is gebou met silindriese stafies. 'n Oopgeslote mikrostrook ossilator is ontwerp en geimplementeer deur negatiewe weerstand te gebruik. Die stelsel se prestasie is bevestig deur gebruik te maak van 'n harmoniese balans simulator in AWR MWO. Verder is 'n enkelbalans menger ontwerp en geimplimenteer via 'n 1800 hibriede verbinding ("rat-race"). Hierdie menger is gebou met mikrostrook transmisielyn. Al die ontwerpte komponente werk goed in vergelyking met die voorspelde resultate. Die LNA, filter, ossilator en menger word gekoppel en gekarakteriseer as 'n vier blok stelsel. Die stelsel werk goed behalwe vir 'n skuif in die IF-sein by laer frekwensies a.g.v. belasting.
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Hsin, Shih-Chieh. "Design and analysis of key components for manufacturable and low-power CMOS millimeter-wave receiver front end". Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45877.
Testo completoAbstract (sommario):
The objective of this dissertation is to develop key components of a CMOS heterodyne millimeter-wave receiver front end. Robust designs are necessary to overcome PVT variations as well as modeling inaccuracies, while with minimum power consumption overhead to facilitate low-power radio for portable applications. Heterodyne receiver topology is adopted because of its robust performances at millimeter-wave frequencies. Device models for both passive and active devices are developed and used in the circuit designs in this dissertation.
Two low-noise amplifiers (LNAs) are developed in this dissertation. The first LNA features a proposed temperature-compensation biasing technique, which confines the gain variation within 5 dB for temperature variation from -5 to 85 Celsius degree. The measured gain and NF are 21 and 6.5 dB, respectively, for 49-mW power dissipation. The second LNA reveals a design technique to tolerate a low-accuracy model at millimeter-wave frequencies. Both LNAs provide full coverage of the FCC 60-GHz band (57-64 GHz).
For the frequency generation circuits, both the IF QVCO and mm-wave VCO are investigated. The inherent bimodal oscillation of QVCOs is analyzed and, for the first time, a systematic measurement technique is proposed to intentionally control the oscillation mode. This technique is further utilized to extend the tuning range of the QVCO, which possesses dual tuning curves without penalty on phase noise. The measurement results of a 13-GHz QVCO in 90-nm CMOS reveals a 21.4% tuning range for continuously tuning from 11.7 to 14.5 GHz. The measured phase noise is -108 dBc/Hz at 1 MHz offset with a core power consumption of 10.8 mW. A millimeter-wave VCO is designed and fabricated in 65-nm CMOS. The VCO is fully characterized under voltage stress to examine the hot-carrier injection effects affecting the performance of a millimeter-wave VCO. The 41.6-47.4 GHz VCO is further integrated into a millimeter-wave down converter. The power-hungry buffer amplifiers are neglected by proper floor planning. Conversion loss of 1.4 dB is obtained with total power consumption of 72.5 mW.
Lastly, a power management system consisting of low-dropout (LDO) regulators is designed and integrated in a 90-nm CMOS millimeter-wave transceiver to provide stable and low-noise supply voltages. Voltage variation issues are alleviated by the LDOs.
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Shubo, Jin, e Zhao Yanshan. "A MICROWAVE DIGITAL FREQUENCY SYNTHESIZER USED FOR S-BAND TELEMETRY RECEIVER". International Foundation for Telemetering, 1997. http://hdl.handle.net/10150/609681.
Testo completoAbstract (sommario):
International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, NevadaThis paper describes a kind of Microwave Digital Frequency Synthesizer used for S-band telemetry receivers. As well known many modern electronic systems employ a Frequency Synthesizer whose spectral purity is critical. The characteristics of a PLL (Phase-Locked Loop) Frequency Synthesizer, such as frequency resolution, phase noise, spurious suppression and switch time, should be compromised in our design. A heterodyne Frequency Synthesis is often considered as a good approach to solve the problem. But it is complicated in structure and circuit. A variable-reference-driven PLL Frequency Synthesizer was introduced which can give an improved trade-off among frequency resolution, phase noise, spurious suppression. In this paper the phase noise and spurious suppression characteristic of variable-reference-driven PLL Frequency Synthesizer is analyzed theoretically and compared with that of the heterodyne Frequency Synthesizer. For engineering application, a practical Microwave Digital Frequency Synthesizer used for telemetry receiver has been designed, which is characterized by simply structure, low phase noise and low spurious output. The output spectrum of experimental measurements is given.
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Legg, Stephen. "Multi-mode receiver systems for cosmic microwave background B-mode polarisation experiments". Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/multimode-receiver-systems-for-cosmic-microwave-background-bmode-polarisation-experiments(11399beb-9f3d-455b-b236-7d612ab1a00b).html.
Testo completoAbstract (sommario):
A measurement of the primordial B-mode polarisation of the Cosmic Microwave Background would provide direct evidence of inflation in the early universe. The extremely weak nature of the B-mode signal necessitates an instrument with a high sensitivity and precise control over systematic effects. Multi-mode antenna feed horns offer higher sensitivity than their single-mode counterparts, however their behaviour is much more complex. The Short Wavelength Instrument for the Polarisation Explorer (SWIPE) onboard the Large Scale Polarisation Explorer (LSPE) is one instrument planning to implement multi-mode feed horns. SWIPE will attempt to detect the primordial B-mode at large angular scales, measuring the sky in three bands at 140, 220 and 240 GHz. A single on-axis High-Density PolyEthylene (HDPE) lens and polarisation-splitting wire grid combine to focus the radiation from the sky onto two focal planes of multi-mode horns feeding bolometric detectors. A large diameter rotating metal-mesh half-wave plate allows both polarisations to be measured by the same pixel, therefore bypassing many detector systematics. Simulations are performed to predict the sky beam for two key pixels: closest to and furthest from the centre of the focal plane. For the 140 GHz channel the cross-polarisation is predicted, and the optimum location at which to place the telescopeâs focus behind the horn aperture to maximise gain and optimise beam shape is investigated. A measurement of the multi-mode horn is performed using a room-temperature bolometer. An investigation is also conducted to assess to what extent the same measurements can be performed using a coherent measurement system such as a vector network analyser. A working coherent measurement technique is devised, however it is limited to horns carrying only the first 3 modes.
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Matinpour, Babak. "Development of a compact monolithic direct down-conversion microwave receiver for wireless applications". Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/13721.
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Dong-soo, Seo, Jang Sung-hoon, Han Sung-hee e Kim Heung-bum. "IMPLEMENTATION OF UNMANNED TELEMETRY GROUND SYSTEM USING MICROWAVE LINK". International Foundation for Telemetering, 2003. http://hdl.handle.net/10150/605331.
Testo completoAbstract (sommario):
International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, NevadaUnmanned Telemetry Ground System (UTGS) was implemented in Defense System Test Center (DSTC), Agency for Defense Development (ADD). The components of UTGS are Antenna, NPS (Network Power Switch), RCB (Receiver/Combiner/Bit synchronizer) and microwave link. We have installed RCB which is composed of receiver, combiner and bit synchronizer. RCB can be controlled and monitored by RS232 serial communication and microwave network. NPS controls its power supplies. UTGS sends PCM stream to local site using E1-class HDSL and microwave link. This system is possible the signal acquisition and reduction of man power at remote site. The usability and performance of UTGS was proved in flight tests. This paper describes the hardware, software design and an implementation of UTGS.
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Crill, Brendan P. "A measurement of the angular power spectrum of the cosmic microwave background with a long duration balloon-borne receiver". Diss., Pasadena, Calif. : California Institute of Technology, 2001. http://resolver.caltech.edu/CaltechETD:etd-08212001-163318.
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Richter, Jürgen. "Resolution of signal components of a resultant electromagnetic wave received in a multipath field of microwave frequencies". Thesis, University of South Wales, 1998. https://pure.southwales.ac.uk/en/studentthesis/resolution-of-signal-components-of-a-resultant-electromagnetic-wave-received-in-a-multipath-field-of-microwave-frequencies(b6dcd52b-f13f-47ff-9a6c-6008577728da).html.
Testo completoAbstract (sommario):
The growing use and demand for microwave communication systems has led to an increase in system density, particularly in urban areas. Consequently this rise has increased the risk of interference. Especially in urban areas the abundant presence of potential obstacles increase the risk of multipath propagation. Multipath propagation on radio links is associated with signal delays and signal level fades on which adversely influences the system performance. For efficient frequency planning the knowledge of the multipath geometries involved is required. This knowledge can be obtained by resolving the experienced multipath field into its constituent components yielding their amplitudes and angles of arrivals at a receiver terminal. Some previous investigations into the resolution of multipath generated height gain curves are documented in the literature. These generally however oncentrate on resolving the two predominant signal components. In an urban environment the number of expected constituent signal components exceed the number of two. Resolution of more than two components requires considerably more effort than this relatively simple case. This thesis provides a component resolution procedure which determines the individual amplitudes and angles of arrival of constituent multipath components. The procedure is applied to the spatial amplitude envelope observed when displacing a receiver incrementally over a distance of a few wavelength through a multipath field. The presented solution can be applied with inexpensive easurement and computational means. For the resolution process it is only required to record the envelope pattern amplitude values without any phase information being required. The use of a single standard antenna as receiver is also sufficient. The procedure does not require data of an array of antenna elements. The performance of the resolution procedure has been tested and validated in an extensive experimental programme which was part of this research. Preliminary results of this project are published in the report of the European COST 235 project.
22
Sarathy, Vivek. "High Spurious-Free Dynamic Range Digital Wideband Receiver for Multiple Signal Detection and Tracking". Wright State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=wright1197910677.
Testo completo
23
Cano, de Diego Juan Luis. "Cryogenic Technology in the Microwave Engineering: Application to MIC and MMIC Very Low Noise Amplifier Design". Doctoral thesis, Universidad de Cantabria, 2010. http://hdl.handle.net/10803/10674.
Testo completoAbstract (sommario):
Algunas aplicaciones tales como la radio astronomía y las comunicaciones con el espacio profundo requieren receptores muy sensibles. Esta tesis trata sobre la tecnología criogénica aplicada a la ingeniería de microondas y se centra en el diseño de amplificadores de muy bajo ruido tanto en tecnología híbrida (MIC) como monolítica (MMIC). El trabajo cubre un ancho campo de conocimiento desde la fabricación mecánica y la configuración de los sistemas hasta el diseño y medida de las aplicaciones finales. Comenzando con pautas y consejos para diseñar sistemas criogénicos (criostatos) este documento profundiza en la medida de parámetros-S y ruido. El diseño de circuitos criogénicos se inicia con el estudio de los efectos de las bajas temperaturas sobre los transistores y componentes de microondas centrándose en los dispositivos de fosfuro de indio (InP). El conocimiento adquirido en este estudio se aplica al diseño de amplificadores de muy bajo ruido en banda Ka.Some applications such as radio astronomy and deep space communications require very sensitive receivers. This dissertation deals with the cryogenic technology applied to the microwave engineering and focuses on the design of very low noise amplifiers both in hybrid (MIC) and monolithic (MMIC) technologies. The work covers a wide field of knowledge from hardware manufacture and system set up to final applications design and measurement. Starting from guidelines and advices to design cryogenic systems (cryostats) this document goes into S-parameters and noise measurements in deep. The design of cryogenic circuits is initialized with the study of the effect of low temperatures on microwave transistors and components focusing in indium-phosphide (InP) devices. The knowledge gained with this study is applied to the design of very low noise amplifiers in Ka-band.
24
Khan, Wasif Tanveer. "Design and development of organically packaged components and modules for microwave and Mm-wave applications". Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53085.
Testo completoAbstract (sommario):
Because of the tremendous amount of media streaming, video calling and high definition TV and gaming, the biggest challenge for the wireless industry is the increasing demand of high data rates. Utilization of mm-wave frequencies is an attractive option to meet this high demand. Recent advances in low cost semiconductor technologies allow realization of low-cost on-chip RF front-ends in the high millimeter wave (mm-wave) frequencies, making it possible to realize compact systems for these application areas. Although integrated circuits (ICs) are one of the main building blocks of a mm-wave system, in order to realize a fully functional wireless system, cost-effective antenna design and packaging are two important pre-conditions. Researchers have investigated and reported low-cost electronics packaging up to 100 GHz to a great extent on ceramic substrates, but mm-wave packaging above 100 GHz is relatively less explored, particularly on organic substrates.
This Ph.D. dissertation demonstrates the design and development of microwave and mm-wave on-chip and on-package antennas and organically packaged components and modules ranging from 20 GHz to 170 GHz. The focus of this research was to design and develop mm-wave components and modules on LCP, to investigate the viability of this organic substrate and development of fabrication techniques in the K- (18-26.5 GHz), V- (50 to 70 GHz), W- (75 to 110 GHz), and D- (110 to 170 GHz) bands. Additionally, a demonstration of a micro-machined on-chip antenna has also been presented. This dissertation is divided in three parts: (1) characterization of liquid crystal polymer from 110 to 170 GHz. (2) development of highly radiation efficient on-chip and AiP antennas, and (3) development of mm-wave modules with the integration of antennas.
25
Aboualmal, Abdulhadi M. A. "Analysis and modelling of the impact of anomalous propagation on terrestrial microwave links in a subtropical region, based on long-term measurements : statistical analysis of long-term meteorological and signal strength measurements in a subtropical region and investigation of the impact of anomalous refractivity profiles on radio propagation in terrestrial microwave wireless systems". Thesis, University of Bradford, 2015. http://hdl.handle.net/10454/14804.
Testo completoAbstract (sommario):
Prevailing propagation phenomena in certain areas play a vital role in deciding terrestrial wireless systems performance. Vertical refractivity profile below 1 km is a critical parameter for designing reliable systems; noting that there is a shortage of upper-air data worldwide. Anomalous phenomena may cause severe signal fading and interference beyond the horizon. The objectives of this thesis are to investigate dominant refractive conditions in the subtropical Arabian Gulf region, develop new approaches and empirical models for evaluating vertical refractivity profiles and relevant propagation parameters in the low troposphere, and to examine the impact of frequently experienced anomalous phenomena on terrestrial microwave links. Twenty-three years of meteorological measurements, from 1990 to 2013, are utilized using spatially separated surface stations and a single radiosonde in the United Arab Emirates (UAE). Profiles of sea level, surface and upper refractivity components are statistically analysed. Three major atmospheric layers; namely 65 m, 100 m and 1 km above the ground are studied to analyse relevant propagation parameters such as sub-refraction, super-refraction, anomalous propagation probability parameter β0 and point refractivity gradient not exceeded for 1% of time. The effective earth radius factor k is investigated using a new weighted averaged approach. In addition, the seasonal structure of atmospheric ducting is dimensioned within 350 m layer above ground. Finally, microwave measurement campaign is conducted using multiple radio links operating in UAE using various frequency bands. The link budget simulations are compared with the signal strength measurements. Fading scenarios are studied against the observed anomalous conditions and several recommendations are concluded.
26
Tong, Cheuk-yu. "Développement d'un récepteur millimétrique à base d'une structure diélectrique incorporant une jonction supraconductrice". Grenoble 1, 1988. http://www.theses.fr/1988GRE10138.
Testo completoAbstract (sommario):
Un nouveau recepteur millimetrique a base d'une combinaison integree: guide d'onde dielectrique non-rayonnant (nrd) modifie, a ete concu et teste aux longueurs d'onde de trois et un millimetre le recepteur comporte une jonction sis (supraconducteur-isolant-supraconducteur) ainsi qu'une structure de couplage originale qui couple l'energie du guide nrd a la jonction
27
Boucenna, Nourreddine. "Contributions a l'etude d'un recepteur heterodyne en ondes submillimetriques utilisant un melangeur a diode schottky". Paris 6, 1986. http://www.theses.fr/1986PA066178.
Testo completoAbstract (sommario):
Formalismes adaptes pour la modelisation d'un duplexeur quasi-optique et d'un systeme d'antenne secondaire. Etude theorique du melangeur a diode schottky submicronique. Criteres d'optimisation d'un systeme melangeur a diode schottky sur gaas. Resultats experimentaux a 890 ghz et discussion dans le cadre de la realisation d'un banc de test de microdiodes schottky a cette frequence
28
Manfrin, Stilante Koch. "Proposta e implementação de um receptor optoeletrônico integrado para redes ópticas passivas (PONs) empregando multiplexação por divisão de comprimento de onda (WDM)". Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/18/18133/tde-01122015-101424/.
Testo completoAbstract (sommario):
O presente trabalho descreve o desenvolvimento e implementação de duas configurações distintas de um receptor optoeletrônico integrado. A primeira configuração é similar a um projeto encontrado na literatura mas apresenta diversas modificações que lhe conferiram melhor desempenho em comparação ao projeto original. A segunda configuração é uma nova proposta deste trabalho. O receptor foi desenvolvido e implementado visando sua aplicação em redes de comunicações ópticas passivas (PONs) de alta velocidade comutadas a pacote, para possibilitar a utilização da técnica de multiplexação em comprimento de onda (WDM), aumentando assim a capacidade de transmissão da rede, em particular no ramo de ligação da rede de serviços com o usuário final, denominado rede de acesso. O principal objetivo do receptor aqui desenvolvido foi proporcionar uma sintonia rápida entre os canais disponíveis na rede, possibilitando sua seleção num tempo inferior àquele necessário para a transmissão de um único pacote de informação, diminuindo assim o atraso de sintonia e, por conseguinte, a perda de informação. Para tanto, os circuitos integrados implementados e caracterizados referem-se aos circuitos de chaveamento eletrônico e do amplificador de transimpedância das duas configurações investigadas. Os dados experimentais obtidos para as duas configurações confirmaram a previsão de chaveamento dos canais de entrada num intervalo de tempo da ordem de alguns nanosegundos, o que é totalmente compatível com a velocidade de transmissão das aplicações a que se destina este receptor (aproximadamente 5 Gbits/s). Adicionalmente, são apresentados os dados experimentais relativos à freqüência de corte, ganho direto, isolação, relação on/off e características de ruído dos circuitos implementados.The present work describes the design and implementation of two configurations of an integrated optoelectronic receiver. The first one is similar to a previously reported design but with some modifications to improve its performance. The second one is a new proposal of this work. The goal of the receiver design and implementation was its application in high bit rate packet-switched passive optical networks (PONs) employing the wavelength division multiplexing (WDM) technique to increase the network capacity, in particular on the connection branch of the network core with the final user, the access network. The main goal of the receiver design was to achieve a fast channel tuning, allowing a tuning time smaller than the required for the transmission of a single information packet, decreasing the tuning latency and, therefore, the rate of information packet loss. In order to accomplish this goal, the implemented and tested integrated circuits include the electronic switching circuit and the transimpedance amplifier for both configurations investigated. The measured data for both configurations confirm the expected input channel switching time results, of about a few nanoseconds, which is certainly useful for the expected bit rate of operation (approximate 5 Gbps). Additionally, experimental results concerning cutoff frequency and bandwidth, direct gain, isolation, on/off ratio, and noise characteristics of both implemented circuits are presented.
29
Guan, Xiang. "Microwave Integrated Phased Array Receivers in Silicon". Thesis, 2006. https://thesis.library.caltech.edu/3834/1/thesis_xiang_final.pdf.
Testo completoAbstract (sommario):
Microwave integrated systems in silicon provide a low cost, low power and high yield solution for wideband data communication, radar, and many other applications. Phased-array systems are capable of steering the radiation beam by electronic means, emulating the behavior of a directional antenna. This dissertation is dedicated to presenting various techniques to implement microwave integrated phased-array receivers in silicon-based technologies in the context of three design examples.
A 24-GHz 0.18-µm complementary metal oxide semiconductor (CMOS) front-end was demonstrated. The front-end consists of a low noise amplifier (LNA) and a mixer. The LNA utilizes a novel topology common-gate with resistive feedthrough to obtain low-noise performance. The entire front-end achieves a 7.7dB noise figure and a 27.5dB power gain.
A fully integrated 8-element 24-GHz silicon germanium (SiGe) phased array receiver was implemented. The receiver uses two-step downconversion and local oscillator (LO) phase shifting with 4-bit resolution. The signal is combined at the 4.8-GHz intermediate frequency. The 16 phases of 19.2-GHz LO signal are generated with a voltage controlled oscillator (VCO) and symmetrically distributed to the phase selectors at all path. Appropriate phase sequence is applied to the phase distribution transmission lines to minimize mismatch. An integrated frequency synthesizer locks the 19.2-GHz VCO output to a 75-MHz external reference. Measured array patterns show a peak-to-null ratio of more than 20dB and a beam steering range covering all signal incident angles.
An integrated 4-element 77-GHz SiGe wideband phased-array transceiver was implemented. Two-step conversion is used at both the receiver and the transmitter. A differential phase of 52 GHz is generated by the VCO and distributed to all RF paths at the transmitter and receiver. The phase shifting is performed at the LO ports of the RF mixers using continuous analog phase shifters. The quadrature signal of the second LO frequency is generated by dividing the VCO frequency by a factor of 2 using a cross-coupled injection-locked frequency divider. The signal combining is performed at IF with an active combining amplifier. The receiver achieves a 41dB gain at 80 GHz with 3 GHz of bandwidth. The 52-GHz-to-50MHz frequency divider chain obtains 7% locking range.
30
Banciu, Marion Gabriel. "Radio frequency and microwave design methods for mobile communications /". 2003. http://www.library.unsw.edu.au/~thesis/adt-NUN/public/adt-NUN20030414.142250/index.html.
Testo completo
31
Hong, Tzu-Chieh, e 洪子傑. "Design and Development of Calibration Signal Source for the Receivers of Array for Microwave Background Anisotropy". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/6ca9fs.
Testo completoAbstract (sommario):
碩士國立中央大學
電機工程研究所
96
Abstract In this thesis, the design and test of calibration source for Array for Microwave Background Anisotropy(AMiBA) telescope receiver are proposed. The implementation of calibration source is separated into two sections. In the first section, the YIG synthesizer was designed. It could export signals about 21~ 26 GHz with interval of 1GHz, which is controlled by an embedded computer. The YIG synthesizer is composed of a YIG oscillator chain, comb generator chain and phase-locked circuit module. The output of YIG oscillator chain is generated by a YIG oscillator followed by an isolator and a coupler. The comb generator chain has a 100MHz crystal oscillator as reference source, which connects to a phase-locked coaxial resonator oscillator to generate 1GHz output signal. A comb generator is then used to generate harmonics of 1GHz, and then the harmonics are mixed with a 21GHz signal from the signal generator (In the future, it will replace by the output of phase-locked dielectric resonator oscillator from AMiBA receiver). The up-converted signal outputs will be 21~26GHz with 1GHz interval. The phase-locked circuit module is then used to integrate the YIG oscillator chain and comb generator chain into a phase-locked-loop. The phase-locked loop incorporates a down conversion mixer, and the outputs of YIG oscillator chain and comb generator chain are connected to the RF and LO port of the mixer. The 25MHz IF output is compared with the reference signal so as to lock the YIG synthesizer output frequency. In the section section, the output of YIG synthesizer is divided into two paths by a dual output amplifier and connected to two mechanical phase shifters which are followed by two switch array. The switched output signal is imported to a multiply-by-4 harmonic generator, and then transmitted to the 13 receivers of AMiBA as a calibration source. In this thesis, we have completed the implementation of the YIG synthesizer and most part of the transmission components. The testing and integration of proposed calibration source with the AMiBA receiver array will be done in the near future.
32
Mondal, Shrijeet. "Digital Control in Microwave Receiver Front-End Components". Thesis, 2014. http://hdl.handle.net/1974/12174.
Testo completoAbstract (sommario):
In this thesis digital control techniques for two receiver front-end components i.e. the downconverter mixer and the modulator are presented. With decrease in size of CMOS-based geometries, decrease in performance and yield of analog components has become an issue. Using the digital components on a System-on-Chip to account for the shortcoming in analog circuitry and thereby developing 'self-calibrating' systems has become a reliable way to address this issue. In the telecommunications industry, this is directly correlated to lower post-fabrication testing times, quicker product development and lower overhead costs.
The first design presented is a 0.13 um CMOS mixer with variable gain capability. A Digital Assist system was put in place to extend the 3-dB bandwidth of the system using a microcontroller. An interpolation routine was used to predict the bias voltages based on variations in frequency and desired input power. The digital-to-analog converter on the microcontroller was used to set the required bias voltages. The mixer's bandwidth was extended from 12GHz to 15GHz using digital assist. The gain of the mixer with the digital assist in place could be varied from 1.2-9.8dB.
The second design presented is a 5.4GHz multi-scheme modulator fabricated in 0.13 um CMOS technology. The modulator is capable of carrying out quadrature amplitude modulation as well as phase-shift keying modulation. The modulator makes use of a novel OTA design to generate a set of orthogonal basis vectors which allows for facile mapping of the modulated data on the I-Q plane. The modulator carries out modulation in 4-PSK, 8-PSK, 4-QAM and 16-QAM modes with a maximum error vector magnitude of only 8.51%. A digital assist model to attain ubiquitous operation inside a system is also presented for this modulator.Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2014-05-03 13:16:06.018
33
Huang, Jyi-Hong, e 黃吉宏. "Study on Microwave-Semiconductor Diffractive Transmitter-Receiver Module". Thesis, 2003. http://ndltd.ncl.edu.tw/handle/71284120039896420033.
Testo completoAbstract (sommario):
碩士國立海洋大學
光電科學研究所
91
Beam scanners are essential components in applications where it is necessary to form and scan an electromagnetic beam. In general, beam scanners are classified into mechanical and non-mechanical styles. Mechanical beam scanners employ a movable antenna. Generally they are heavier than desired and often expensive. Non-mechanical beam scanners are based on phased array antennas and employ phase shifters to individual elements or groups of elements[1]. The phased array approach offers many advantages, but the multiplicity of phase shifters makes such systems costly. Therefore, developing much inexpensive, light and speedy beam scanners will attribute practical value in delivery and reception of electromagnetic waves[2-8]. Recently, one group have developed a non-mechanical beam scanner which forms and steers a beam of microwave or higher frequency radiation using light-modulated photoconducting antennas[4-5,7-8]. Scanners based on this approach promise to be fast and inexpensive. Control of the electronic properties of photoconductors with light has both a long history [9] and is actively being investigated. Recently, phase control of propagating radiation in dielectric wave guides has been studied [10]. Biased photoconductors were shown to emit wide band, broad but steerable beams extending to THz [11]. Femtosecond laser pulses controlled by spatial light modulators impinging on semiconductor surfaces have been used to produce steerable narrow beams of submillimeter radiation [12]. The goal of this thesis is using a semiconductor or photoconductor wafer in which a spatially varying density of charge carriers has been created by optical injection. The induced charge carriers, electrons and/or holes, alter the dielectric constant of the wafer locally and thereby attenuate and reflect incident electromagnetic radiation. With suitable parameters, unilluminated parts of the semiconductor allow the incident electromagnetic wave to be transmitted. Because the wafer responds rapidly to changes in optical injection, it is possible rapidly change the diffractive conditions and thus rapidly change the beam direction.
34
"Coherent integrated receiver for highly linear microwave photonic links". UNIVERSITY OF CALIFORNIA, SANTA BARBARA, 2009. http://pqdtopen.proquest.com/#viewpdf?dispub=3342064.
Testo completo
35
Tsai, Han-Ting, e 蔡涵婷. "Microwave Wideband CMOS Receiver and RF-to-Digital Converter". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/tw4ugd.
Testo completoAbstract (sommario):
碩士國立交通大學
電信工程研究所
102
This thesis discusses two circuit designs. One is a wideband CMOS receiver, and the other is a RF-to-digital converter. The 0.18um-CMOS, 17-26 GHz (K-band) receiver contains RF LNA, wideband mixer, IF amplifier, and LO frequency doubler. The circuit architecture, simulation results, chip layout and measured results are presented. The conversion gain of mixer is 0 dB. The IF-RF isolation is 40 dB. The RF-to-digital converter consists of sample-and-hold circuit, preamplifier, comparator, and encoder. The circuit architecture, simulation results and 90nm-CMOS and 0.18-CMOS layouts are discussed.
36
Cheng, Sheng Jen, e 鄭盛仁. "A Super Heterodyne Receiver for 24-GHz Microwave Anti-collision RADAR Module". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/92301130941609493841.
Testo completoAbstract (sommario):
碩士長庚大學
電子工程學系
100
THIS MASTER DEGREE THESIS, “DESIGNS OF THE 24-GHZ CMOS RF FRONT-END CHIP AND MILLIMETER-WAVE CIRCUIT ”, DEALS WITH THE DESIGN AND SIMULATION OF AN ANTI COLLISION RADAR MODULE WHICH IS MAINLY CONSIST OF LOW NOISE AMPLIFIER (LNA), BALUN, VOLTAGE CONTROL OSCILLATIOR (VCO), I&QDIVIDER4, UWB UP-CONVERSION MIXER, DOWN-CONVERSION MIXER, IFAMP, QUADRATURE DOWN-CONVERSION MIXER AND PHASE COMBINER. BRIEFLY SUMMARIZED THE MAJOR TOPICS DISCUSSED IN THIS THESIS, IN ORDER OF APPEARANCE, ARE AS FOLLOWS : 1. INTRODUCTION OF ANTI COLLISION RADAR MODULE,ITS BACKGROUND, DESIGN MOTIVATION AND ANTI COLLISION FRONT END MODULE ARE DISCUSSED IN DETAILS. 2. DESIGN OF LNA WITH BALUN. THE SIMULATED POWER CONSUMPTION, CONVERSION GAIN AND NOISE FIGURE OF LNA ARE 14.58MW, 15.9DB, AND 4.7DB RESPECTIVLY. FOR THE BALUN CIRCUIT THE CONVERSION GAIN AND NOISE FIGURE ARE 3.43DB AND -3.57DB RESPECTIVLY. 3. DESIGN OF VCO AND THEN MODIFICATION IT AGAIN FOR BETTER PERFORMANCE. FOR THE 1ST VCO THE MEASURED OUTPUT FRQUENCY , THE PHASE NOISE AND THE POWER CONSUMPTION ARE 10.27 GHZ TO 10.39 GHZ, -106 DBC/HZ, 4.14 MW RESPECTIVLY. FOR THE MODIFIED VCO THESE VALUES ARE 22.94GHZ TO 25.26GHZ, -103DBC/HZ AND 5.04MW RESPECTIVELY. 4. SIMULATION OF I&QDIVIDER4 WHOSE POWER CONSUMPTION IS 7.84MW, LOCK RANGE 800MHZ, AND OUTPUT POWER IS -6.5DBM. 5. SIMULATION OF UWB UP-CONVERSION MIXER, THE OUTPUT FREQUENCY RANGE IS 3.1-30.1 GHZ WITH POWER CONSUMPTION 11.6MW AND CONVERSION GAIN 1.52 DB WITH LEASS THAN -30DB ISOLATION. 6. THEN COMES SIMULATION OF DOWN-CONVERSION MIXER WHOSE POWER CONSUMPTION AND CONVERSION GAIN ARE 15,12 MW AND 5.83 DB WITH ISOLATION LESS THAN -30DB. 7. IFAMP SIMULATED POWER CONSUMPTION, CONVERSION GAIN AND NOISE FIGURE ARE 36.1MW, 9.2DB, AND 3. 34 DB RESPECTIVLY. 8. THE SIMULATED POWER CONSUMPTION OF QUADRATURE DOWN-CONVERSION MIXER AND PHASE COMBINER 23.76MW WITH CONVERSION GAIN -4.15DB AND ISOLATION LESS THAN -30DB. 9. LASTLY THE SUPER HETERODYNE RECEIVER SYSTEM SIMULATED POWER CONSUMPTION IS 9.34 DB, P-1 IS -31DBM, IMAGE REJECTION LESS THAN -40 DBM, CONVERSION GAIN 25.6 DB AND NOISE FIGURE -9.4DBM.
37
張玉文. "A Fully Polarimetric Microwave Scatterometer-Design and Implementation of Transmitter / Receiver Modules". Thesis, 2001. http://ndltd.ncl.edu.tw/handle/79814960219735915765.
Testo completoAbstract (sommario):
碩士國立中央大學
電機工程研究所
89
In this thesis, the transmitter/receiver of a X-band fully polarimetric scatterometer is designed and implemented. Due to the high attenuation of the electromagnetic waves in the coaxial cables at X-band, the superheterodyne structure is applied on the design of transmitter/receiver. A vector network analyzer (VNA) is used as the signal source. Due to VNA''s high ability in signal process, many features such as system calibration and time gating can be easily implemented and performed. The signal from the VNA, which ranges from 1 GHz to 2 GHz, is upconverted to 9 GHz to 10 GHz by mixers. An Amplifier is used to compensate the signal attenuation and thus raise the dynamic range and measurement sensitivity of the scatterometer. A computer-controlled switching system is implemented to alternate different polarization states, so the fully polarization measurement can be achieved. An single dual-mode pyramidal horn in conjunction with circulators is applied to avoid the antenna interference inherent in the multi-antenna system. Therefore the backscatter can be measured in short ranges. In order to conduct automatic measurements, a computer program is developed for data acquisition, switching control, and system calibration.
38
LIN, HE-JIN, e 林合晉. "Study of improving efficiency of receiver for microwave wireless power transmission system". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/ftmj68.
Testo completoAbstract (sommario):
碩士逢甲大學
通訊工程學系
106
The methodology of improving the receiver efficiency of wireless power transmission system has been studied. Two parts of the circuit are used to improve the system efficiency. The first part is to design a high-gain antenna; the second part is to design a three-step boost rectifier circuit. In the first part of the research on high-gain antennas, four antennas were designed: a finger-meander antenna, a capacitive-load finger-meander antenna, a finger-meander antenna array, and a capacitive-load finger-meander antenna array. The highest gain antenna is the capacitive-load finger-meander antenna array, with a reflection loss of -20 dB, a gain of 7.74 dBi, and an area of 65.5 x 170 mm2. The second part is a boost rectifier circuit design. Using third-order boost rectifier circuit architecture and Schottky diodes with the low critical voltage of the body increases the conversion efficiency. The size of the implemented circuit is 30mm x 15mm, and the return loss is 21 dB at 2.4 GHz of the operation frequency. The highest efficiency is 40% with 10K ohms load. After system integration, the measured results show that the transmitter of the wireless power transmission system can provide 31 dBm output power at 2.4 GHz. It can turn on the LED lamp under a distance of 4.8 meters with the capacitive-load finger-meander antenna array and the boost rectifier circuit.
39
Marklein, Eric. "Design of a Two-Receiver Interferometer on Motorized Tracks". 2008. https://scholarworks.umass.edu/theses/122.
Testo completoAbstract (sommario):
A 94.8 GHz interferometric imaging system utilizing aperture synthesis and tomography is developed for the Center for Advanced Sensor and Communication Antennas. Whereas typical interferometer designs employ multiple antennas to synthesize an aperture for image reconstruction, this unique interferometer will reproduce a scene's brightness temperature with only two antennas. To achieve this, the aperture synthesis is done with one antenna remaining stationary while the second antenna is moved at discrete increments along two controlled tracks. The two signals received by the antennas are cross-correlated to produce measured visibility function samples. The visibility samples reconstruct the scene brightness temperature through an inverse Fourier transform relationship.
40
Wang, Shih-Chieh, e 王詩傑. "The Design and Implementation of Receiver Modules for a 36.5 GHz Microwave Radiometer". Thesis, 2003. http://ndltd.ncl.edu.tw/handle/51121964056005085742.
Testo completoAbstract (sommario):
碩士國立中央大學
電機工程研究所
91
In the thesis,the 36.5 GHz Microwave Total Power Digital Radiometer is designed,implemented and simulated. Include RF front end, analog to digital converter and digital correlator. The superheterodyne structure is applied on the design of receiver frond end. The 36.5 GHz RF signal is then downconverted to 500 MHz IF signal using a mixer-preamplifier. The gain of the IF amplifier are determined in the measurement to achieve the full-scale input of analog-to-digital converter. The flash analog to digital converter digitizes full scale input into 6-bit digital words at an update rate of 1 Giga Sample Per Second (GSPS) . It not only results in the required sensitivity of the radiometer, it also makes the system possibly extended in the future using the direct-sampling approach. Two statistical model of noise signal in digital radiometer are also studied. The narrow band noise signal is modeled as a Gaussian random process. A computer program is developed to help understand the relationship between Noise-Equivalent sensitivity and quantization resolution. Finally the prototype of 36.5 GHz Microwave Total Power Digital Radiometer is presented. Future works will involve realizing the digital correlator to verify the sensitivity predicted by statistical models.
41
Huang, Che Yen, e 黃哲彥. "Microwave Large-signal model establishment of Enhancement-mode AlGaAs/InGaAs pHEMT and Optical Communication Receiver Design". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/95412343471522537202.
Testo completoAbstract (sommario):
碩士長庚大學
電子工程學研究所
97
A modified Angelov model for Small Sizes and Scaling Gate Width in High Performance AlGaAs/InGaAs Enhancement-Mode pHEMTs is presented which achieves a good agreement with the device DC and microwave performance. This model is based on the Angelov model, by modifying the formula to have comprehensive bias dependent descriptions for nonlinear behaviors of the devices. The small sizes transistor can reduce the IC layout area. In the forward of Optical communication, the Photo Diode will translate the 850nm optical signal to electrical signal, after that, the electrical signal will be amplified by TIA(Transimpedance Amplifier) and LA(Limiting Amplifier). We will use different bandwidth broaden technique to satisfy the requirement of 10Gb/s. For example, C-peaking tech, L-peaking tech, and the compensation tech. In this work, we use the L-peaking and compensation tech in TIA. The schematic of LA is Cherry-Hooper Amplifier. At the end of the research, we hope we can integrate the PD+TIA+LA in the future.
42
Yang, Tzu-Ching, e 楊子慶. "Optimal Design Low Noise Amplifier and Microwave/Millimeter-Wave Dual-Mode Receiver with Transmission Zeros Filter". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/526uqa.
Testo completoAbstract (sommario):
碩士國立交通大學
電信工程研究所
103
This thesis consists of two parts, including a low noise amplifier and a 5/60 GHz dual-mode receiver with transmission zeros filter. In chapter 2, we describe the low noise amplifier. And then, we use trifilar-type component implementing low noise amplifier in 0.18μm SiGe technology. Otherwise, we use 0.15μm PHEMT technology to discuss temperature effects in two different self-bias architectures of low noise amplifier. Chapter 3 introduces the circuits in 5/60 GHz dual-mode receiver will be illustrated. It is implemented in 0.18-μm CMOS technology. In order to improve the signal interference, we use an active RF filter with transmission zeros on 5GHz path. Furthermore, A passive mixer is designed for 60 GHz signal to solve the insufficient ft problem in 0.18-μm technology by using schottky diode of which the ft is nearly 200 GHz.
43
Lin, Chia-Hsing, e 林佳興. "Implementation of Microwave Mixers for ISM and Ku-band Applications and the Study of the Ku-Band Receiver Module". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/10221471401121943768.
Testo completoAbstract (sommario):
碩士國立成功大學
光電科學與工程研究所
94
Abstract The first part of the thesis is used the UMC 0.18um 1P6M CMOS process to implement the low voltage, low noise double balance Gilbert Mixer. This mixer uses the dynamic current source to reduce the output noise current and uses the cmos transistor pair to improve the gain in the RF stage. The operation voltage of this mixer is below 1 voltage, conversion gain is better than 5 dB and noise figure is below 10 dB. The chip size of the mixer is just 0.555 ×0.475 . The second part of the thesis is the development of the new structure star mixer. The traditional star mixer needs cross-balun to deliver the RF and LO signal. But the cross-balun wastes too much area. So this new star mixer replace cross-balun by double-balun. This new structure can reduce the circuit size of the traditional star mixer. The conversion loss is 11 dB. The isolation is below 17 dB between LO port and IF port. The isolation is below 17 dB between LO port and RF port. The third part of the thesis is the development of a receiver with RO4003C for Ku band applications. It includes a low noise amplifier、a mixer、an intermediate frequency amplifier and a filter module. The measured results of the low noise amplifier show that the conversion gain is 5 dB and the noise figure is 3.45 dB; The measured results of the mixer show that the conversion loss is 12.61 dB and the isolation between LO and IF or RF and IF are large than 30 dB. The measured results of the intermediate frequency amplifier show that the conversion gain is 14.7 dB and the output P1dB is 16.8 dBm. The measured results of the filter show that the insertion loss is 3.7 dB and the input return loss is 15 dB. Finally, the receiver system is assembled with all module in the housing. The measured output power is -0.33 dBm.
44
Crill, Brendan Patrick. "A Measurement of the Angular Power Spectrum of the Cosmic Microwave Background with a Long Duration Balloon-borne Receiver". Thesis, 2001. https://thesis.library.caltech.edu/3180/4/bpc_thesis.pdf.
Testo completoAbstract (sommario):
This thesis describes BOOMERANG; a balloon-borne telescope and receiver designed to map the Cosmic Microwave Background (CMB) at a resolution of 10' from the Long Duration Balloon (LDB) platform. The millimeter-wave receiver employs new technology in bolometers, readout electronics, cold re-imaging optics, millimeter-wave filters, and cryogenics to obtain high sensitivity to CMB anisotropy. Sixteen detectors observe in 4 spectral bands centered at 90, 150, 240 and 400 GHz. The wide frequency coverage, the long flight duration, the optical design and the observing strategy all provide strong rejection of systematic effects. We report the in-flight performance of the instrument during a short test flight from Palestine, Texas, that mapped 230 square degrees and during a 10.5 day stratospheric balloon flight launched from McMurdo Station, Antarctica, that mapped ~ 2000 square degrees of the sky. The Antarctic data yielded a measurement of the angular power spectrum of the CMB between 50 < ℓ < 600 which shows a peak at ℓpeak = 197 ± 6 (1σ error). A maximum likelihood estimation of cosmological parameters within the cold dark matter (CDM) paradigm of structure formation indicates that the universe is flat with a precision of ~ 6% and that the density of baryons in the universe may be slightly higher than previously thought. The combination of observations of large scale structure (LSS) and the BOOMERANG power spectrum implies the presence of both dark matter and dark energy, or the existence of Einstein's cosmological constant.
45
Hoda, Nazmul. "Receiver Channelizer For FBWA System Confirming To WiMAX Standard". Thesis, 2007. http://hdl.handle.net/2005/614.
Testo completoAbstract (sommario):
Fixed Broadband Wireless Access (FBWA) is a technology aimed at providing high-speed wireless Internet access, over a wide area, from devices such as personal computers and laptops. FBWA channels are defined in the range of 1-20 MHz which makes the RF front end (RFE) design extremely challenging. In its pursuit to standardize the Broadband Wireless Access (BWA) technologies, IEEE working group 802.16 for Broadband Wireless Access has released the fixed BWA standard IEEE 802.16 – 2004 in 2004. This standard is further backed by a consortium, of leading wireless vendors, chip manufacturers and service providers, officially known as Wireless Interoperability for Microwave Access (WiMAX).
In general, any wireless base station (BS), supporting a number of contiguous Frequency Division Multiplexed (FDM) channels has to incorporate an RF front end (RFE) for each RF channel. The precise job of the RFE is to filter the desired channel from a group of RF channels, digitize it and present it to the subsequent baseband system at the proper sampling rate. The system essentially has a bandpass filter (BPF) tuned to the channel of interest followed by a multiplier which brings the channel to a suitable intermediate frequency (IF). The IF output is digitized by an ADC and then brought to the baseband by an appropriate digital multiplier. The baseband samples, thus generated, are at the ADC sampling rate which is significantly higher than the target sampling rate, which is defined by the wireless protocol in use. As a result a sampling rate conversion (SRC) is performed on these baseband samples to bring the channel back to the target sampling rate. Since the input sampling rate need not be an integer multiple of the target sampling rate, Fractional SRC (FSRC) is required in most of the cases. Instead of using a separate ADC and IF section for each individual channels, most systems use a common IF section, followed by a wideband ADC, which operates over a wide frequency band containing a group of contiguous FDM channels. In this case a channelizer is employed to digitally extract the individual channels from the digital IF samples. We formally call this system a receiver channelizer. Such an implementation presents considerable challenge in terms of the computational requirement and of course the cost of the BS. The computational complexity further goes up for FBWA system where channel bandwidth is in the order of several MHz. Though such a system has been analyzed for narrow band wireless systems like GSM, to the best of our knowledge no analysis seems to have been carried out for a wideband system such as WiMAX.
In this work, we focus on design of a receiver channelizer for WiMAX BS, which can simultaneously extract a group of contiguous FDM RF channels supported by the BS. The main goal is to obtain a simple, low cost channelizer architecture, which can be implemented in an FPGA. There are a number of techniques available in the literature, from Direct Digital Conversion to Polyphase FFT Filter Banks (PFFB), which can do the job of channelization. But each of them operates with certain constraints and, as a result, suits best to a particular application. Further all of these techniques are generic in nature, in the sense that their structure is independent of any particular standard. With regard to computational requirement of these techniques, PFFB is the best, with respect to the number of complex multiplications required for its implementation. But it needs two very stringent conditions to be satisfied, viz. the number of channels to be extracted is equal to the decimation factor and the sampling rate is a power of 2 times baseband bandwidth. Clearly these conditions may not be satisfied by different wireless communication standards, and in fact, this is not satisfied by the WiMAX standard.
This gives us the motivation to analyze the receiver channelizer for WiMAX BS and to find an efficient and low cost architecture of the same. We demonstrate that even though the conditions required by PFFB are not satisfied by the WiMAX standard, we can modify the overall architecture to include the PFFB structure. This is achieved by dividing the receiver channelizer into two blocks. The first block uses the PFFB structure to separate the desired number of channels from the input samples. This process also achieves an integer SRC by a factor that is equal to the number of channels being extracted. This block generates baseband outputs whose sampling rates are related to their target sampling rate by a fractional multiplication factor. In order to bring the channels to their target sampling rate, each output from the PFFB block is fed to a FSRC block, whose job is to use an efficient FSRC algorithm to generate the samples at the target sampling rate. We show that the computational complexity, as compared to the direct implementation, is reduced by a factor, which is approximately equal to the square of the number of channels.
After mathematically formulating the receiver channelizer for WiMAX BS, we perform the simulation of the system using a software tool. There are two basic motives behind the simulation of the system which has a mathematical model. Firstly, the software simulation will give an idea whether the designed system is physically realizable. Secondly, this will help in designing the logic for different blocks of the system. Once these individual blocks are simulated and tested, they can be smoothly ported onto an FPGA.
For simulation purpose, we parameterize the receiver channelizer in such a way that it can be reconfigured for different ADC sampling rates and IF frequencies, by changing the input clock rate. The system is also reconfigurable in terms of the supported channel bandwidth. This is achieved by storing all the filter coefficients pertaining to each channel type, and loading the required coefficients into the computational engine. Using this methodology we simulate the system for three different IF frequencies (and the corresponding ADC sampling rates) and three different channel types, thus leading to nine different system configurations. The simulation results are in agreement with the mathematical model of the system.
Further, we also discuss some important implementation issues for the reconfigurable receiver channelizer. We estimate the memory requirement for implementing the system in an FPGA. The implementation delay is estimated in terms of number of samples.
The thesis is organized in five chapters. Chapter 1 gives a brief introduction about the WiMAX system and different existing channelization architecture followed by the outline of the proposed receiver channelizer. In chapter 2, we analyze the proposed receiver channelizer for WiMAX BS and evaluate its computational requirements. Chapter 3 outlines the procedure to generate the WiMAX test signal and specification of the all the filters used in the system. It also lists the simulation parameters and records the results of the simulation. Chapter 4 presents the details of a possible FPGA implementation. We present the concluding remarks and future research directions in the final chapter.
46
Bridger, Andrew B. "Increasing the spectral efficiency of contunous phase modulation applied to digital microwave radio : a resource efficient FPGA receiver implementation : [a thesis presented in partial fulfilment of the requirements for the degree of Master of Engineering in Electronics and Computer Systems Engineering at Massey University, Palmerston North, New Zealand ] EMBARGED UNTIL 1 JUNE 2012". 2009. http://hdl.handle.net/10179/1366.
Testo completoAbstract (sommario):
In modern point to point microwave radio systems used to backhaul cellular voice and data traffic, quadrature amplitude modulation (QAM) is the norm. These systems require a highly linear power amplifier which is expensive and has relatively low power efficiency. Recently, continuous phase modulation (CPM) has been deployed in this market. The CPM transmitted waveform has a constant envelope and so a non-linear RF power amplifier can be used. This significantly reduces cost and improves power efficiency. Two important disadvantages of CPM are receiver complexity and inferior spectral efficiency compared to QAM. This thesis demonstrates a 50% spectral efficiency improvement over an existing CPM configuration without loss of detection efficiency. This is achieved by moving to coherent demodulation and extending the duration of the CPM phase pulse to 3 symbol periods. This new CPM configuration of h=1/4, M=4, L=3, is evaluated against ETSI requirements for a 28 MHz channel carrying 24 E1 circuits. Simulation of the receiver floating point model demonstrates all requirements are met. The detection efficiency requirement is exceeded by 4.7 dB. Carrier recovery, phase and timing synchronisation are assumed to be ideal. The 50% increased symbol rate, coherent reception and a longer smoother phase pulse, conspire to increase receiver complexity substantially. The Viterbi algorithm is used to perform maximum-likelihood detection resulting in a 128 state trellis. This application has a stringent cost requirement that limits the implementation target to a Field Programmable Gate Array (FPGA) costing less than US$30. To demonstrate this demanding cost target is met, the two most computationally expensive receiver functions, the branch metric unit and path metric processing unit, are implemented in VHDL and targeted to a Xilinx Spartan 3A-DSP 1800 FPGA. The implementation uses 67% of the available logic resources, thus meeting the cost requirement. The branch metric unit is implemented using a distributed arithmetic technique that performs the equivalent of 27.6 giga-multiplies/s, consuming only 23% of the available FPGA logic cells. This is very efficient compared to a conventional approach using all the FPGA’s embedded multipliers which combined can only achieve 21 giga-multiplies/s. The Viterbi path metric processing unit is implemented using a more conventional state-parallel architecture. To reduce state metric routing complexity, states are grouped into radix-4 units comprising dual add-compare-select (ACS) units. By utilising a spare cycle in the deep ACS pipeline, each ACS unit processes two output state metrics, thus halving the number of ACS units required. This implementation uses 44% of the available FPGA resources and meets timing at 204.5 MHz, exceeding the throughput requirement of 54 Mbit/s.
47
Καραθανάσης, Κωνσταντίνος. "Θεωρητική ανάλυση και πειραματική μελέτη ενός παθητικού μικροκυματικού συστήματος για διαγνωστικές εφαρμογές με χρήση ραδιομετρίας". Thesis, 2008. http://nemertes.lis.upatras.gr/jspui/handle/10889/941.
Testo completoAbstract (sommario):
Η εφαρμογή της μικροκυματικής ραδιομετρίας έχει επεκταθεί στο χώρο της ιατρικής, καθότι τα τελευταία χρόνια γίνονται έρευνες με σκοπό την εκμετάλλευση των ιδιοτήτων της μεθόδου στη διαγνωστική αλλά και στη θεραπευτική ιατρική. Στα πλαίσια μιας διδακτορικής διατριβής που εκπονήθηκε στο Εργαστήριο Μικροκυμάτων και Οπτικών Ινών (ΕΜΟΙ) της σχολής Ηλεκτρολόγων Μηχανικών και Μηχανικών Υπολογιστών του Εθνικού Μετσόβιου Πολυτεχνείου και ολοκληρώθηκε το 2003, κατασκευάστηκε ένα τρισδιάστατο σύστημα παθητικής μικροκυματικής ραδιομετρικής απεικόνισης (ΜiRaIS) για διαγνωστικές εφαρμογές εγκεφάλου. Στη συγκεκριμένη μέθοδο χρησιμοποιείται μια αγώγιμη ελλειψοειδής κοιλότητα, ώστε να επιτευχθεί μέγιστη συγκέντρωση και εστίαση ακτινοβολίας που εκπέμπει το φυσικό σώμα ενδιαφέροντος, σε συνδυασμό με ραδιομετρικούς δέκτες ολικής ισχύος και ομοιοκατευθυντικές κεραίες λήψης στο φάσμα συχνοτήτων 1-4GHz.
Στην παρούσα διπλωματική εργασία γίνεται θεωρητική και πειραματική μελέτη ενός νέου μικροκυματικού ραδιομετρικού συστήματος. Η αρχή λειτουργίας του είναι όμοια με αυτήν του MiRaIS, δηλαδή πλήρως παθητική και μη επεμβατική. Η βασική διαφορά του είναι ότι χρησιμοποιεί μια τροποποιημένη ελλειψοειδή κοιλότητα η οποία βελτιώνει την εργονομία του συστήματος διατηρώντας παράλληλα της ιδιότητες εστίασης του πρωτότυπου ελλειψοειδούς.
Στη θεωρητική μελέτη, με τη βοήθεια του λογισμικού High Frequency Structure Simulation (HFSS) που βασίζεται στη μέθοδο των πεπερασμένων στοιχείων, αναλύονται δυο μέθοδοι για τη βελτίωση των ιδιοτήτων εστίασης του συστήματος (πχ. βάθος διείσδυσης της ακτινοβολίας, χωρική διακριτική ικανότητα) με τη χρήση διηλεκτρικών υλικών και υλικών με αρνητικό δείκτη διάθλασης (Left Handed Materials-LHM). Στην πρώτη περίπτωση, τα υλικά αυτά χρησιμοποιούνται ως στρώματα προσαρμογής που τοποθετούνται γύρω από το μοντέλο κεφαλιού για την επίτευξη βηματικής αλλαγής του δείκτη διάθλασης στη διεπιφάνεια αέρα-μοντέλου ανθρώπινου κεφαλιού. Στη δεύτερη προσέγγιση του προβλήματος, χρησιμοποιείται μια σφαίρα από διηλεκτρικό σε συνδυασμό με ένα στρώμα προσαρμογής από LHM για την καλύτερη εστίαση του συστήματος. Προς την ίδια κατεύθυνση, στη δεύτερη αυτή περίπτωση χρησιμοποιείται επίσης ένας ελλειψοειδής ανακλαστήρας μειωμένου όγκου το εσωτερικό του οποίου είναι γεμάτο με διηλεκτρικό με χαμηλές απώλειες, με τα αποτελέσματα να δείχνουν σημαντική βελτίωση της χωρικής διακριτικής ικανότητας του συστήματος.
Η πειραματική διάταξη τοποθετήθηκε σε ανηχοϊκό θάλαμο όπου και πραγματοποιήθηκαν όλες οι μετρήσεις. Στις πειραματικές διαδικασίες που ακολουθήθηκαν, χρησιμοποιήθηκαν ομοιώματα νερού (phantoms) σε διάφορα μεγέθη και θερμοκρασίες για την επιβεβαίωση της διατήρησης των ιδιοτήτων εστίασης του νέου ελλειψοειδούς ανακλαστήρα. Επίσης, διενεργήθηκαν μετρήσεις με στρώματα προσαρμογής φτιαγμένα από διηλεκτρικά υλικά, τα οποία τοποθετούνταν γύρω από το αντικείμενο ενδιαφέροντος, για την πληρέστερη κατανόηση της επίδρασης των υλικών αυτών στις ιδιότητες εστίασης του συστήματος και για την επιβεβαίωση των αντίστοιχων θεωρητικών αποτελεσμάτων.In the framework of a PhD thesis which was completed in the Laboratory of Microwaves and Fiber Optics (MFOL), School of Electrical and Computer Engineering, National Technical University of Athens (NTUA) in 2003, a Three Dimensional Passive Microwave Radiometry Imaging System (MiRaIS) was designed and constructed for brain diagnostic applications. The novelty of the proposed methodology consists in the use of a conductive ellipsoidal cavity to achieve maximum peak of radiation pattern in order to measure the intensity of the microwave energy, radiated by the medium of interest, by using two microwave total power radiometers and relevant non-contacting antennas within the range of 1-4GHz. In the present thesis, a new microwave radiometry system is theoretically and experimentally studied. It has the same operation principal with MiRaIS as it operates in an entirely non-invasive and passive manner. Its main difference is that it comprises a modified ellipsoidal cavity which improves the system’s ergonomy preserving the focusing properties of the original cavity. In the theoretical study, two methods for the improvement of the system’s focusing properties (e.g. penetration depth of the electromagnetic field, spatial sensitivity) using dielectric materials and left-handed materials (LHM) are tested with the use of a commercially available software tool, High Frequency Structure Simulation (HFSS). In the first case, those materials are used as matching layers placed around the human head model for the achievement of stepped change of the refraction index on the air-human head model interface. On the second approach, a sphere made of dielectric material is used in conjunction with a LHM matching layer in order to improve the system’s spatial sensitivity. Towards the same direction, a reduced volume ellipsoidal cavity filled with low loss dielectric material is used showing promising results. The experiments were performed inside an anechoic chamber providing maximum accuracy avoiding any external intergerence. In the experimental procedures that were performed, water phantoms of several sizes and temperatures were used in order to confirm that the new ellipsoidal beamformer maintains the focusing properties of the original one. Also, measurements were conducted using dielectric matching layers, placed around the medium of interest, in order to fully understand the effect of those materials in the system’s focusing properties as well as confirm the relative theoretical results.