Thesis (M.S.E.E.)--University of Puerto Rico, Mayagüez Campus, 2005. / Tables. Printout. Includes bibliographical references (leaves146-148).

Tapered slot antennas (TSAs) have seen considerable application in the millimeter-wave portion of the spectrum. Desirable characteristics of TSAs include symmetric E- and H-plane antenna patterns, and broad non-resonant bandwidths. We investigate extension of TSA operation toward higher frequencies in the thermal infrared (IR), using a metal-oxide-metal diode as the detector. Several different infrared TSA design forms are fabricated using electronbeam lithography and specially developed thin-film processes. The angular antenna patterns of TSA-coupled diodes are measured at 10.6 micrometer wavelength in both E- and H-planes, and are compared to results of finite-element electromagnetic modeling using Ansoft HFSS. Parameter studies are carried out, correlating the geometric and material properties of several TSA design forms to numerical-model results and to measurements. A significant increase in antenna gain is noted for a dielectric-overcoat design. The traveling-wave behavior of the IR TSA structure is investigated using scattering near-field microscopy. The measured near-field data is compared to HFSS results. Suggestions for future research are included

Yes / The antenna array designed to operate over 0.450-0.475 Terahertz comprises two dielectric resonators (DRs) that are stacked vertically on top of each other and placed on the surface of the slot antenna fabricated on a silicon substrate using standard CMOS technology. The slot created in the silicon substrate is meandering and is surrounded by metallic via-wall to prevent energy dissipation. The antenna has a maximum gain of 4.5dBi and radiation efficiency of 45.7% at 0.4625 THz. The combination of slot and vias transform the antenna to a metamaterial structure that provides a relatively small antenna footprint. The proposed series-fed double DRs on-chip antenna array is useful for applications in THz integrated circuits. / Partially supported by innovation programme under grant agreement H2020-MSCA-ITN-2016 SECRET-722424 and the financial support from the UK Engineering and Physical Sciences Research Council (EPSRC) under grant EP/E0/22936/1.

Yes / In this letter a novel on-chip array antenna is investigated which is based on CMOS 20μm Silicon technology for operation over 0.6-0.65 THz. The proposed array structure is constructed on three layers composed of Silicon-Ground-Silicon layers. Two antennas are implemented on the top layer, where each antenna is constituted from three sub-antennas. The sub-antennas are constructed from interconnected dual-rings. Also, the sub-antennas are interconnected to each other. This approach enhances the aperture of the array. Surface waves and substrate losses in the structure are suppressed with metallic via-holes implemented between the radiation elements. To excite the structure, a novel feeding mechanism is used comprising open-circuited microstrip lines that couple electromagnetic energy from the bottom layer to the antennas on the top-layer through metasurface slot-lines in the middle ground-plane layer. The results show the proposed on-chip antenna array has an average radiation gain, efficiency, and isolation of 7.62 dBi, 32.67%, and -30 dB, respectively. / H2020-MSCA-ITN-2016 SECRET-722424 and the financial support from the UK Engineering and Physical Sciences Research Council (EPSRC) under grant EP/E0/22936/1

[pt] Os sistemas que operam em banda larga necessitam de radiadores que atendam eletricamente a banda de frequência utilizada. As antenas com características de independência da frequência, em particular as antenas espirais, têm encontrando cada vez mais utilização nesses sistemas, seja em aplicações comercias ou militares. Esta dissertação tem por objetivo a análise de desempenho de antenas espirais do tipo fenda em cavidades, pela aplicação do método dos momentos. Serão consideradas cavidades com a face oposta à antena constituída por um condutor perfeito ou acoplada a uma estrutura de microondas com matriz de espalhamento conhecida. Essa estrutura de microondas, poderá simular, por exemplo, uma ou mais camadas de material absorvente.Um modelo numérico foi desenvolvido, e a partir dele foi elaborado um programa de computador, para determinar as características de radiação de antenas espirais em cavidade. São apresentados e comparados os resultados obtidos para três configurações de antenas espirais de Arquimedes do tipo fenda: sem cavidade, com cavidade condutora e com um material absorvente colocado sobre a face da cavidade oposta a abertura da antena. / [en] Broad band systems need radiators to operate over the entire frequency band. Frequency independent antennas, in particular spiral antennas, are finding increasing application in such systems, for commercial or military purposes. This dissertation has for objective the analysis of performance of cavity-backed slot spiral antenna, by applying the moment method . For this study it will be taken into account cavities with the face opposing to the antenna consisting of a perfect conductor or connected to a structure of microwaves with known scattering matrix. This microwave structure will be able to simulate, for example, one or more layers of absorbing material. A numerical model was developed, and based on it, it was elaborated a computer program to determine the radiation characteristics of cavity-backed spiral antennas. The results surveyed for three configurations of slot Archimedean spiral antenna are presented and compared: without cavity, with conducting cavity, and with an absorbing material placed on the cavity opposite to the antenna.

An active, broadband antenna module amenable for use in low cost phased arrays is proposed. The module consists of a Vivaldi antenna integrated with a frequency conversion integrated circuit. A method of orthogonally mounting endfire antennas onto an array motherboard is developed using castellated vias. A castellated active isolated Vivaldi antenna package is designed, fabricated, and measured. An 8x1 phased array of castellated, active Vivaldi antenna packages is designed and assembled. Each element has approximately one octave of bandwidth centered in X-band, and each is mounted onto a coplanar waveguide motherboard. Radiation patterns of the array are measured at several frequencies and scan angles.

This thesis presents solutions and studies related to the design of wideband antennas for wireless handheld terminal applications. A method of electrically shortening the terminal chassis length to obtain resonance at high frequencies has been proposed and evaluated, thereby increasing the antennas impedance bandwidth. No significant effect on the lower frequency band in a dual-band antenna prototype has been observed, making the method suitable for multi-band applications. The chassis has further been utilized as a zero-thickness 0.9 - 2.7 GHz high efficiency antenna by inserting a notch in the chassis center, and a feasibility study for typical phones has been performed. Additionally, the effect of talk position on the chassis wave-mode has been investigated, where the standard equivalent circuit model for terminal antennas has been modified to include the presence of the users head. The model has been used to explain measured and simulated effects concerning frequency detuning, efficiency reduction and bandwidth enhancements when the terminal is placed in talk position. The use of a hands-free earpiece cord is currently mandatory for FM radio reception as the cord is utilized as antenna. However, there is currently a market driven demand for removing the cord requirement since many modern phones are equipped with speakers and Bluetooth headsets. In this thesis, an active ferrite loop antenna is proposed as an internal replacement/complement with a performance of -23 dB (G/T degradation) compared to a full-size lossless dipole in urban environments. Also, a modification to the cord is suggested for DVB H reception. Complex matching networks have been investigated to increase the bandwidth of dual band PIFA antennas, and a printed dual band dipole has been integrated with a modified Marchand balun for dual resonance at two separate frequency bands, thus covering the commercial cellular bands 824-960 and 1710-2170 MHz with a single antenna.

[pt] Devido às propriedades de banda larga e polarização circular, as antenas espirais tornaram-se bastante atrativas para diversos serviços de telecomunicações modernos e móveis. Neste trabalho uma antena espiral tipo fenda apoiada em uma cavidade cilíndrica metálica foi analisada. Por causa de sua geometria complexa, optou-se por um método numérico híbrido, realizado através de uma implementação de elementos mistos do método dos elementos finitos - integral de fronteira. Baseado nesta formulação, um programa computacional foi desenvolvido. Um grande esforço foi realizado a fim de escrever o programa de maneira que o armazenamento e as necessidades computacionais fossem mínimos, boa parte conseguida pela aplicação das condições de contorno na superfície metálica. Com o objetivo de melhor explorar a geometria do problema, definiu-se uma malha de elementos finitos onde a parte que cabia a abertura foi dividida em quadriláteros enquanto que no restante da superfície, elementos triangulares foram utilizados. Repetiu-se então esta malha ao longo da altura da cavidade, de maneira que hexaedros e prismas formaram a malha final. Para cada espécie de elemento, funções de base vetoriais específicas foram aplicadas. A fim de verificar a precisão do algoritmo, o mesmo programa computacional foi utilizado na análise de uma antena tipo fenda retangular, também apoiada em uma cavidade cilíndrica metálica. / [en] Known for the properties of broadband and circular polarization, spiral antennas have become sufficiently attractive for services of modern and mobile telecommunications. In this work a cavity-backed slot spiral antenna was analyzed. Because of its complex geometry, it was chosen a hybrid numerical method, carried through an implementation of mixing elements of the finite elements - boundary integral method. Based in this formulation, a computer program was developed. A great effort was carried out in order to write the program thus the computational storage and necessities were minimum, good part obtained by application of the boundary conditions on the metallic surface. With the goal of better exploring the geometry of the problem, a mesh of finite elements was defined where the part that fit the aperture was divided into quadrilaterals, while that in the rest of the surface, triangular elements were used. By repeating this mesh along the height of the cavity, hexahedrals and prisms formed the final mesh. For each kind of element, specific vector base functions were applied. In order to verify the accuracy of the algorithm, the same computational program was used in the analysis of a cavity-backed slot rectangular antenna.

<p>This thesis considers integration of antennas and active electronics manufactured on the same substrate. The main topic is on-chip antennas for commercial silicon processes, but hybrid integration using printed circuit board technology is also addressed.</p><p>The possible use of micromachining techniques as a means of reducing substrate losses of antennas manufactured on low resistivity silicon wafers is investigated. Compact dipole, loop, and inverted-F antennas for the 20-40 GHz frequency range are designed, implemented, and characterized. The results show significantly improved antenna efficiency when micromachining is used as a post-processing step for on-chip antennas manufactured in silicon technology.</p><p>High resistivity wafers are used in a commercial silicon germanium technology to improve the efficiency of dipole antennas realized using the available circuit metal layers in the process. Monolithically integrated 24 GHz receivers with on-chip antennas are designed and evaluated with regard to antenna and system performance. No noticeable degradation of the receiver performance caused by cross talk between the antenna and the integrated circuit is observed.</p><p>For low frequency antenna arrays, such as base station antennas, hybrid integration of active devices within the antenna aperture is treated. A compact varactor based phase shifter for traveling wave antenna applications is proposed and evaluated. Electrically steerable traveling wave patch antenna arrays, with the phase shifters implemented in the same conductor layer as the radiating elements, are designed and manufactured in microstrip technology. It is experimentally verified that the radiation from the feed network and phase shifters in the proposed antenna configuration is small.</p>

<p>This thesis presents solutions and studies related to the design of wideband antennas for wireless handheld terminal applications. A method of electrically shortening the terminal chassis length to obtain resonance at high frequencies has been proposed and evaluated, thereby increasing the antennas impedance bandwidth. No significant effect on the lower frequency band in a dual-band antenna prototype has been observed, making the method suitable for multi-band applications. The chassis has further been utilized as a zero-thickness 0.9 - 2.7 GHz high efficiency antenna by inserting a notch in the chassis center, and a feasibility study for typical phones has been performed. Additionally, the effect of talk position on the chassis wave-mode has been investigated, where the standard equivalent circuit model for terminal antennas has been modified to include the presence of the users head. The model has been used to explain measured and simulated effects concerning frequency detuning, efficiency reduction and bandwidth enhancements when the terminal is placed in talk position.</p><p>The use of a hands-free earpiece cord is currently mandatory for FM radio reception as the cord is utilized as antenna. However, there is currently a market driven demand for removing the cord requirement since many modern phones are equipped with speakers and Bluetooth headsets. In this thesis, an active ferrite loop antenna is proposed as an internal replacement/complement with a performance of -23 dB (G/T degradation) compared to a full-size lossless dipole in urban environments. Also, a modification to the cord is suggested for DVB H reception.</p><p>Complex matching networks have been investigated to increase the bandwidth of dual band PIFA antennas, and a printed dual band dipole has been integrated with a modified Marchand balun for dual resonance at two separate frequency bands, thus covering the commercial cellular bands 824-960 and 1710-2170 MHz with a single antenna.</p>