Dissertations / Theses on the topic 'RECONFIGURABLE PATCH ANTENNA'

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 78-80).
Reconfigurable antennas with adaptable frequency, pattern, and polarization offer flexibility and size reduction for wireless systems that must increasingly execute multiple missions with less volume. These antennas will also complement anticipated cognitive radio systems, which promise more efficient use of the electromagnetic spectrum. Microscale liquid metal switches are proposed to overcome the series loss, mechanical fatigue, and limited power handling reliability of common methods of antenna reconfiguration such as semiconductor diodes and microelectromechanical switches. The proposed microswitches consist of mercury droplets that selectively connect solid metal traces. Both fluidic and electrostatic switch actuation mechanisms are investigated, and an electrostatic switch is demonstrated. Electrostatically actuated switches are designed into a compact single-feed patch antenna configurable between two communication frequency bands and a GPS band with different circular polarizations. The antenna topology is based on a corner truncated square patch with switched sets of extensions to achieve resonant frequency and axial ratio control. Measurements of reconfigurable prototypes demonstrate frequency and polarization configurability in good agreement with full-wave simulations. The proposed reconfiguration mechanism is compared to other methods, and future directions for the integration of microfluidics in reconfigurable radio frequency systems are proposed.
by Steven Christopher Yee.
S.M.

ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, Nevada
Reconfigurable patch antenna integrated with RF mircoelectromechanical system (MEMS) switches is presented in this paper. The proposed antenna radiates circularly polarized wave at selectable dual frequencies (4.7 GHz and 7.5GHz) of high frequency ratio (1.6:1). The switches are incorporated into the diagonally-fed square patch for controlling the operation frequency, and a rectangular stub attached to the edge of the patch acts as the perturbation to produce the circular polarization. Gain of proposed antenna is 5 - 6dBi, and axial ratio satisfies 3dB criterion at both operating frequencies. The switches are monolithically integrated on quartz substrate. The antenna can be used in applications requiring frequency diversity of remarkable high frequency ratio.

Els serveis de telecomunicacions i sistemes radar estan migrant a freqüències mil•limètriques (MMW), on es disposa d 'una major amplada de banda i conseqüentment d'una major velocitat de transmissió de dades. Aquesta migració requereix de l'ús de diferents tecnologies amb capacitat d'operar a la banda de freqüències mil•limètriques (30 a 300 Ghz), i més concretament en les bandes Ka (26,5 - 40GHz), V (50 – 75GHz) i W (75 – 110GHz). En moltes aplicacions i sobretot en aquelles on l'antena forma part d'un dispositiu mòbil, es cerca poder utilitzar antenes planes, caracteritzades per tenir unes dimensions reduïdes i un baix cost de fabricació. El conjunt de requeriments es pot resumir en obtenir una antena amb capacitat de reconfigurabilitat i amb un baix nivell de pèrdues en cada una de les bandes de freqüència. Per tal d'afrontar aquests reptes, les dimensions de les antenes mil•limètriques, juntament amb els tipus de materials, toleràncies de fabricació i la capacitat de reconfigurabilitat ens porten a l'ús de processos de microfabricació. L'objectiu d'aquesta tesis doctoral és l'anàlisi dels conceptes mencionats, tipus de materials, geometries de línia de transmissió i interruptors, en el context de les freqüències mil•limètriques, així com la seva aplicació final en dissenys d'antenes compatibles amb els processos de microfabricació. Finalment, com a demostració s'han presentat dissenys específics utilitzables en tres aplicacions a freqüències mil•limètriques: Sistemes de Comunicació per Satèl•lit (SCS) a la banda Ka, Xarxes d'àrea personal inalàmbriques (WPAN) a la banda V i sistemes radar per l'automoció a la banda W. La primera part d'aquesta tesis consisteix en l'anàlisi d'algunes tecnologies circuitals a freqüències mil•limètriques. S'han presentat els materials més utilitzats a altes freqüències (Polytetrafluoroethylene or Teflon (PTFE), Quartz, Benzocyclobuten polymer (BCB) i Low Temperature Co-fired Ceramic (LTCC)) i s'han comparat en termes de permitivitat i tangent de pèrdues. També s'inclou un estudi de pèrdues a altes freqüències en les principals línies de transmissió (microstrip, stripline i CPW). Finalment, es presenta un resum dels interruptors RF-MEMS i es comparen amb els PIN diodes i els FET. En la segona part, es presenten diferents agrupacions d'antenes amb la capacitat de reconfigurar la polarització i la direcció d'apuntament. S'han dissenyat dos elements base reconfigurables en polarització: CPW Patch antena i 4-Qdime antena. La primera antena consisteix en un element singular amb interruptors RF-MEMS, dissenyada per operar a les bandes Ka i V. La segona antena consisteix en una arquitectura composta on la reconfigurabilitat en polarització s'obté mitjançant variant la fase d'alimentació de cada un dels quatre elements lineals. La fase és controlada mitjançant interruptors RF-MEMS ubicats en la xarxa de distribució. L'antena 4-Qdime s'ha dissenyat per operar en les bandes V i W. Ambdós elements base s'han utilitzat posteriorment pel disseny de dues agrupacions d'antenes amb capacitat de reconfigurar l'apuntament del feix principal. La reconfigurabilitat es dur a terme utilitzant desfasadors de fase d'1 bit. La part final de la tesis es centra en les toleràncies de fabricació i en els processo de microfabricació d'agrupacions d'antenes mil•limètriques. Les toleràncies de fabricació s'han estudiat en funció dels error d'amplitud i fase en cada element de l'agrupació, fixant-se en les pèrdues de guany, error d'apuntament, error en l'amplada de feix, errors en el nivell de lòbul secundari i en l'error en la relació axial. El procés de microfabricació de les diferents antenes dissenyades es presenta en detall. Els dissenys de l'antena CPW Patch reconfigurable en polarització i apuntament operant a les bandes Ka i V, s'han fabricat en la sala blanca del Cornell NanoScale Science & Technology Facility (CNF). Posteriorment, s'han caracteritzat l'aïllament i el temps de resposta dels interruptors RF-MEMS, i finalment, el coeficient de reflexió, el diagrama de radiació i la relació axial s'han mesurat a les bandes Ka i V per les antenes configurades en polarització lineal (LP) i circular (CP).
Telecommunication services and radar systems are migrating to Millimeter-wave (MMW) frequencies, where wider bandwidths are available. Such migration requires the use of different technologies with the capability to operate at the MMW frequency band (30 to 300GHz), and more specifically at Ka- (26.5 to 40GHz), V- (50 to 75GHz) and W-band (75 to 110GHz). For many applications and more concretely those where the antenna is part of a mobile device, it is targeted the use of planar antennas for their low profile and low fabrication cost. A wide variety of requirements is translated into a reconfiguration capability and low losses within each application frequency bandwidth. To deal with the mentioned challenges, the MMW antenna dimensions, together with the materials, fabrication tolerances and reconfigurability capability lead to microfabrication processes. The aim of this thesis is the analysis of the mentioned concepts, materials, transmission lines geometries and switches in the MMW frequencies context and their final application in antenna designs compatible with microfabrication. Finally, specific designs are presented as a demonstration for three MMW applications: Satellite Communication Systems (SCS) at Ka-band, Wireless Personal Area Network (WPAN) at V-band and Automotive Radar at W-band. The first part of this thesis consist to analyze some MMW circuit technologies. The four most used materials at MMW frequencies (Polytetrafluoroethylene or Teflon (PTFE), Quartz, Benzocyclobuten polymer (BCB) and Low Temperature Co-fired Ceramic (LTCC)) have been presented and compared in terms of permittivity (εr) and loss tangent (tanδ). An study of the main transmission lines attenuation (microstrip, stripline and CPW) at high frequencies is included. Finally, an overview of the RF-MEMS switches is presented in comparison with PIN diodes and FETS switches. The second part presents different polarization and beam pointing reconfigurable array antennas. Two polarization-reconfigurable base-elements have been designed: CPW Patch antenna and 4-Qdime antenna. The first consists of a single reconfigurable element with integrated RF-MEMS switches, designed to operate at Ka- and V-band. The second antenna presented in this thesis has a composed architecture where the polarization reconfigurability is obtained by switching the phase feeding for each of the four linear polarized elements in the feed network with RF-MEMS switches. The 4-Qdime antenna has been designed to operate at V- and W-band. The two base-elements have been used to design two beam pointing reconfigurable antenna arrays. Using phased array techniques, beamsteering is computed and implemented with 1-bit discrete phase-shifter. The final part of the thesis is focused into the fabrication tolerances and microfabrication process of Millimeter-wave antenna arrays. The fabrication tolerances have been studied as a function of the amplitude and phase errors presented at each elements array, focusing on the gain loss, beam pointing error, Half-Power Beamwidth (HPBW) error, sidelobe level error and axial ratio error. The microfabrication process for the designed antennas is presented in detail. Polarization- and pointing- reconfigurable CPW Patch antenna operating at Ka- and V- band have been fabricated in a clean-room facility at Cornell NanoScale Science & Technology Facility (CNF). The RF-MEMS switches isolation and time response have been characterized. Finally, the reflection coefficient, radiation pattern and axial ratio have been measured at Ka- and V-band for the fabricated antennas configured in Linear Polarization (LP) and Circular Polarization (CP).

Antennas enable wireless communication by transmission and reception of electromagnetic (EM) signals, which carry information is space. Signal reception and hence the quality of service depends significantly on the antenna properties, e.g. radiation pattern, operational frequency, and polarization. Legacy antennas, with their fixed properties, fail to adapt to the changing environment and degrade signal quality. Reconfigurable antennas (Ras) capable of changing their properties dynamically increase the capacity and data rate of wireless systems while offering a compact design. However, these advantages come at the cost of increased complexity compared to legacy antennas. Therefore it is important to design Ras with minimal complexity. To that end, this dissertation focuses on the development of a novel approach, three different Ras operation at three different frequency bands have been designed, fabricated and characterized. First RA works at the 5GHz band (4.9-5.1GHz) and obtains on current beam steering and 3-dB beam width variability. An algorithm to choose the optimum mode of operation has also been developed. The design approach introduced in first RA has been exploited to design the second RA, which achieves beam steering and beam width variability for two polarizations and operates a the 28 GHz band (27.5-28.3 GHz). The third RA operates at the 3GHz band and simultaneously reconfigures impedance and radiation patterns.

The master's thesis deals with the design and implementation of a reconfigurable patch antenna. The antenna is fed by a microstrip transmission line. To the microstrip feeder, tuning stubs are connected. Each stub matches the input impedance of the antenna to 50 ? for different operation frequencies. Stubs can be individually connected to the feeder by PIN diodes; operation frequency of the antenna can be switched that way. In the project, the antenna is initially designed for antenna substrate RO3006. Then, the design will be converted to the substrate ARLON AD600 selected for the realization. In the project, modifications of stubs will be proposed to properly connect the PIN diodes. Functionality of the designed antenna will be verified by modeling in Ansoft Designer. The last part will be dealt with implementation of the antenna and the experimental measurement of their properties.

Microstrip antennas are widely used in wireless communications because of their compatibility, low profile, low power consumption and low cost. The capability to select the frequency is essential for diverse missions and this is achieved by a Reconfigurable Antenna. Resonant frequency of an antenna is changed by reconfiguring its geometrical structure. To achieve reconfigurability RF switching devices such as PIN diodes , photoconductive switches, micro-electromechanical system (MEMS) switches and FETs can be used. Electromagnetic Bandgap (EBG) Structures that are those structures in which each element follows periodicity. Hence using EBG structures in a conventional patch antenna increase bandwidth and provide better suppression of harmonics . This major project combines these two structures designing a reconfigurable patch antenna with EBG structure in which PIN diodes are used as switch as they provide fast switching speeds, reasonably high current handling capabilities, reliability and ease of modelling. First of all the phase reflection diagram for a unit cell of proposed EBG is shown, after that bandgap of full EBG structure is shown using suspended transmission line method. Different EBG structures’ bandgaps are also compared. Then the EBG structure is combined with a reconfigurable patch antenna and simulation results are presented in terms of return loss, VSWR and radiation pattern. A comparison between simulated results for reconfigurable antenna with and without EBG structures for return loss and radiation pattern is also provided. All the above simulations are carried out by CST STUDIO SUITE 2014.

碩士
國立彰化師範大學
電機工程學系
95
The designs of a reconfigurable ring patch antenna are proposed and studied in this dissertation. The thesis is mainly divided into three topics. First, the design of a ring patch antenna with wideband and dual-frequency operations is presented. The antenna consists of a parasitic square ring patch that is shorted to the ground plane through two shorting walls and is excited by a top-loaded coaxial probe. For the proposed design, while the side length of the square ring patch is about 0.3 free-space wavelengths and the antenna height is less than 0.1 free-space wavelengths, a 10 dB-input-impedance bandwidth of more than 50 % can be achieved. Also, the antenna can provide stable monopole-like conical radiation patterns across the impedance bandwidth. In addition, it is also found that two different resonant modes, patch-loaded monopole mode and normal patch mode, can be simultaneously excited in the shorted patch antenna structure by a coupling rectangular strip inside the ring patch. The antenna can radiate monopole-like and broadside patterns at the two operating frequencies, respectively. Second, a reconfigurable patch antenna with the functions of switchable radiation patterns, and polarizations is presented. The antenna is composed of a ring patch and four shorting walls. By controlling the connections states between the ring patch and shorting walls through pin diodes, the antenna can be operated at different modes to achieve the switching of the radiation patterns and polarizations. Moreover, three pairs of the shorting walls with various widths are integrated into the antenna to excite the patch-load monopole mode, and the resonant frequency can be changed by activating various pair of the shorting walls. From the obtained results, the three operating frequencies can occupy a successive impedance bandwidth, which makes the antenna with wide band operation.

碩士
國立臺灣大學
電信工程學研究所
105
This thesis presents a reconfigurable antenna with pattern diversity for indoor WLAN IEEE 802.11ac applications. First, two kinds of antennas are proposed in this thesis. The first kind is the beam tilt antenna, which may generate tilt-beam patterns toward 4 directions in the horizontal plane. The other kind is the broadside microstrip antenna that may generate broadside patterns. In view of the compact design, both kinds of antennas are integrated into the same PCB module (80×80×2.4 〖mm〗^3). The PCB stacking consists of three layers, including the antenna patch layer, the ground layer, and the microstrip feeding layer. All antennas are fed with probe feeds and are extended to the SMA connectors for testing purpose. In addition, to realize the switched pattern function, we integrated IC switch in our antenna design and used IC switch to change the excited port. Additionally, we also investigated the impact of the employed switch on the antenna impedance matching, and then we introduced some parameters to fine tune the antenna performance. Finally, we built two prototypes (non-switch Antenna, switch Antenna), and use USRP verify our design in wireless communication

碩士
國立交通大學
電信工程系所
94
In this thesis, novel reconfigurable patch antennas for quadri-polarization diversity are designed and fabricated. To satisfy the requirement of polarization diversity in the integrated communication systems, we propose the idea of switching the polarization statuses of antennas by controlling the bias of pin diodes in this thesis. This way, antennas are operated between dual-linear and dual-circular polarization. The polarization statuses of antennas are decided by either different resonating structures or different feeding signals. Therefore, by controlling the bias of pin diodes to change the resonating structures or different feeding signals, quadric-polarization antennas can be realized easily. Presently few antennas can be operated both in dual-linear and dual-circular statuses. In this thesis we apply pin diodes in patch antenna and aperture coupled antenna. By the two design methods mentioned above, single antenna can be operated between dual-linear polarization and dual-circular polarization.

First reconfigurable antenna came into existence in early 1980s. Reconfigurable antennas provide various functions in operating frequency, polarization & radiation patterns since it can be used to avoid noise sources, improve system gain & security [1]. Reconfiguring the Frequency is the major issue & lot of recent work has been done on frequency reconfigurability A Barium Strontium Titanate (BST) based reconfigurable Aperture-coupled patch antenna on high resistivity silicon substrates with beam steering capability using PIN doides has been proposed in this paper. For low dielectric constant region in silicon substrate, Micromachined technique is used. Varying voltage across BST layer changes its permittivity thereby tunable frequency is achieved and switching p-i-n diodes will steer the beam. A Novel structure is proposed which gives high directivity (> 6 dB), Good gain (> 5 dB), low VSWR (<1.5), low control voltages (<80V) & 60° HPBWs & also The proposed reconfigurable aperture coupled microstrip patch antenna array with beam scanning capability has almost 40 degree scanning angle and BST based reconfiguring frequency is achieved with good gain and directivity

Communication and reconnaissance systems are requiring increasing flexibility concerning functionality and efficiency for multiband and broadband frequency applications. Circuit-based reconfiguration mechanisms continue to promote radio frequency (RF) application flexibility; however, increasing limitations have resulted in hindering performance. Therefore, the implementation of a "wireless" reconfiguration mechanism provides the required agility and amicability for microwave circuits and antennas without local overhead. The wireless reconfiguration mechanism in this thesis integrates dynamic, fluidic-based material systems to achieve electromagnetic agility and reduce the need for "wired" reconfiguration technologies. The dynamic material system component has become known as electromagnetically functionalized colloidal dispersions (EFCDs). In a microfluidic reconfiguration system, they provide electromagnetic agility by altering the colloidal volume fraction of EFCDs - their name highlights the special considerations we give to material systems in applied electromagnetics towards lowering loss and reducing system complexity. Utilizing EFCDs at the RF device-level produced the first circuit-type integration of this reconfiguration system; this is identified as the coaxial stub microfluidic impedance transformer (COSMIX). The COSMIX is a small hollowed segment of transmission line with results showing a full reactive loop (capacitive to inductive tuning) around the Smith chart over a 1.2 GHz bandwidth. A second microfluidic application demonstrates a novel antenna reconfiguration mechanism for a 3 GHz microstrip patch antenna. Results showed a 300 MHz downward frequency shift by dielectric colloidal dispersions. Magnetic material produced a 40 MHz frequency shift. The final application demonstrates the dynamically altering microfluidic system for a 3 GHz 1x2 array of linearly polarized microstrip patch antennas. The parallel microfluidic capillaries were imbedded in polydimethylsiloxane (PDMS). Both E- and H-plane designs showed a 250 MHz frequency shift by dielectric colloidal dispersions. Results showed a strong correlation between decreasing electrical length of the elements and an increase of the volume fraction, causing frequency to decrease and mutual coupling to increase. Measured, modeled, and analytical results for impedance, voltage standing wave ratio (VSWR), and radiation behavior (where applicable) are provided.

碩士
國立彰化師範大學
電機工程學系
97
Designs of frequency and polarization reconfigurable microstrip patch antennas with conical radiation are respectively presented in this thesis. For the reconfigurable frequency antenna design, a monopolar patch antenna structure is used to generate conical radiation patterns. The frequency switching is realized by controlling four diodes to reconfigure the size of the shorted rectangular patch of the monopolar patch antenna. Each diode connects one side of the shorted rectangular patch and an open stub. For the reconfigurable polarization antenna design, the used antenna structure is single feed and involves two resonant modes, in which a 4-element-array loop antenna mode, producing horizontal polarization, and a monopolar patch antenna mode, producing vertical polarization. By properly exciting and coupling the two resonant modes, circular polarization radiation can be obtained. Moreover, the polarization switching is achieved by controlling four diodes to reconfigure the number of the shorting walls. Two prototypes for the abovementioned reconfigurable frequency and polarization antennas are implemented, respectively, and their dimensions are obtained by numerical analyzing with HFSS. From the measured results, the operating frequency of the reconfigurable frequency antenna has a tunable range from 1820 ~ 2480 MHz, and good omni-directional radiation patterns are observed across the available operating frequencies. As for the reconfigurable polarization antenna, the measured results exhibit the antenna prototype has the ability of switching polarization, and the operating frequencies of the right-hand and left-hand circular polarization occur at 2900 and 2420 MHz, respectively. Also, both the operating frequencies have a return loss of less than 10 dB and an axial ratio of less than 3 dB.

碩士
國立中央大學
電機工程學系
105
The operating frequency of an antenna can be made reconfigurable by incorporating tuning elements. In this thesis, microstrip patch antennas are loaded with variable capacitors (varactors) to acquire frequency tunability. We design and fabricate two kinds of frequency-reconfigurable microstrip patch antennas, both of which use ferroelectric varactors with barium strontium titinate (BSTO) as the dielectric material for the capacitive loading. One of the microstrip patch antennas uses benzocyclobutene (BCB) as its dielectric whereas the other patch antenna uses high-resistivity silicon substrate. The operating frequency of the frequency-reconfigurable patch antenna with BCB as its dielectric is set at around 15 GHz. The ferroelectric capacitors and the patch are connected using the BCB stacked via process developed by our lab. Measurement results show that, when the bias voltage of the varactor is tuned from 0 V to 25 V, the operating frequency of the antenna varies from 13.8 GHz to 14.3 GHz, which translates into a 3.5% frequency tuning range (FTR). The operating frequency of the microstrip patch antenna with high-resistivity silicon as its dielectric is also designed to be around 15 GHz. The ferroelectric varactors are connected to the ground plane on the backside of the silicon substrate by through substrate vias (TSVs). Measurement results of this antenna show that the operating frequency is fixed at 9.7 GHz. No frequency tunability is observed. We find that the reason why the antenna is not tunable is because the annealing temperature for the BSTO thin film is too low for this sample. As for the large frequency shift, it is due to a mistake in layout. The layout mistake results in an unexpected silicon-nitride capacitor with a large capacitance, which becomes part of the capacitive loading. In this thesis, we successfully realize a frequency-reconfigurable microstrip patch antenna with BCB as its dielectric and with ferroelectric varactors as its capacitive loading. On the other hand, we successfully fabricate a capacitively loaded microstrip patch antenna using the TSV process we develop. Though the measured operating frequency has deviated from the designed value and cannot be tuned, we have discovered the reasons that result in these problems. We believe that the expected performance can be obtained after these issues are resolved.

The objective of work is to design and develop Polarization Reconfigurable Micro strip patch antenna which radiate electromagnetic wave of various orthogonal patterns. A progression of parametric study was done to get that how the features of the antenna depends on dimensions and material of geometry. Simulation of antenna has to be done by using CST microwave studio and HFSS. Antennas of various geometry have to be simulated and fabricated which radiates various orthogonal patterns of electromagnetic wave. The first antenna is to design and develop dual feed reconfigurable circularly polarized microstrip patch antenna feeding with microstrip line. By using switch and two feedline antenna is capable to radiate RHCP and LHCP. The second antenna is to design and develop reconfigurable circularly polarized microstrip antenna with single feed line, feeding with Proximity coupled method. Antenna is capable to radiate LHCP and RHCP with the help of proper switching action and reconfigurable feedline. The third design is to design and develop dual feed Quadri-Polarization States microstrip patch antenna feeding with microstrip line. With the help of two feedline and 4 diodes antenna is capable to radiate VLP, HLP, LHCP, RHCP. On the patch two opposite corners are slotted and connect by using two PIN diodes. The forth design is to design and develop polarization reconfigurable microstrip antenna with single feedline, feeding with microstrip line. Antenna is capable to radiate electromagnetic wave of various pattern like LP, LHCP, RHCP. Various S-parameters, surface current distribution, axial ratio, and radiation patterns are shown for various antennas. Antennas are capable to radiate various orthogonal patterns which increase the diversity gain. Therefore, antenna have a features of multipath effects reduction i.e. reduction of fading and interference and antenna can be used as polarization diversity array

碩士
長庚大學
電子工程學系
99
This thesis presents two designs of reconfigurable antennas by using diode switches such that the main beam directions or polarization directions of the antennas can be changed to achieve the best receiving or transmission effects. The first one is a circular patch antenna with a ring slot on it. On the ring slot, diode switches are placed at 30° interval. By selectively turning on or off these diode switches, the polarization of the antenna can be changed such that it is possible to receive linear polarization waves in different directions. The measured 10-dB bandwidth is 2.26~2.4 GHz, and the measured antenna gain at the center frequency of 2.32 GHz is 5.36 dB. The second one is a cavity-back ring slot antenna. Similar to previous one, diode switches are placed at 30° interval on the slot. By selectively turning on or off these diode switches, the main beam direction can be switched on the horizon. Simulated and experimental results show that the first one is indeed possible to be in practical use. However, due to the effect of finite ground, the main beam of the second one is elevated above the horizon, reducing its value in practical use.