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. 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. 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. 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.

Submitted by Lara Oliveira (lara@ufersa.edu.br) on 2017-07-14T18:14:07Z No. of bitstreams: 1 JonasRSS_DISSERT.pdf: 2555775 bytes, checksum: 1cffc3792b8fe12b4067e7bc74ee127d (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2017-07-18T15:08:15Z (GMT) No. of bitstreams: 1 JonasRSS_DISSERT.pdf: 2555775 bytes, checksum: 1cffc3792b8fe12b4067e7bc74ee127d (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2017-07-18T15:11:33Z (GMT) No. of bitstreams: 1 JonasRSS_DISSERT.pdf: 2555775 bytes, checksum: 1cffc3792b8fe12b4067e7bc74ee127d (MD5) / Made available in DSpace on 2017-07-18T15:11:41Z (GMT). No. of bitstreams: 1 JonasRSS_DISSERT.pdf: 2555775 bytes, checksum: 1cffc3792b8fe12b4067e7bc74ee127d (MD5) Previous issue date: 2016-12-02 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The antennas in nano-metric scales are part of a line of research that has been gaining strength in recent years, being the target of numerous studies and publications in several universities in Brazil and around the world. Nano antennas are characterized as a promising new branch in the development of devices capable of being applied in different areas, in addition to communication. Occupying a prominent place in the new era of technologies, the nano antennas, here restricted only to dipole and microstrip, generate enormous expectations about this new revolution, not only between researchers, but also in a part of society. Currently, wireless communications require that radiator devices have wide bandwidth and miniaturization for mobile devices, so this dissertation discusses the potential application of antennas for communications in the frequency range in Terahertz. At these frequencies, there are numerous restrictions on the propagation of signals, so high performance antenna are necessary to allow communication with reduced losses. The purpose of this work is to study some configurations and types of antennas, such as microstrip antenna and dipole antenna, with application in the subterahertz frequency, which can be used, for example, in internal networks, medicine, photovoltaic power generation, spectroscopy, near-field microscopy and high quality images. Some configurations of antennas with various materials for communications in the frequency range will be presented to verify the feasibility of the use of nano dipole antennas and miniaturized microstrip antennas in this type of application. The methodology adopted suggests the comparison of the simulated results, through the software Ansoft HFSS ® and CST Microwave Studio ®, with the results of other published works / As antenas em escalas nanométrica fazem parte de uma linha de pesquisa que vem aumentando nos últimos anos, sendo alvo de inúmeros estudos e publicações. As nanoantenas caracterizam-se como um novo e promissor ramo no desenvolvimento de dispositivos capazes de ser aplicados em diferentes áreas, além da comunicação. Ocupando lugar de destaque na nova era das tecnologias, as nanoantenas, aqui restritas somente as de dipolo e microfita, geram enorme expectativas. Atualmente as comunicações sem fio requer que os dispositivos radiadores possuam uma ampla largura de banda e miniaturização para dispositivos móveis, assim, essa dissertação discute a aplicação potencial de antenas para comunicações na faixa de frequência em Terahertz. Nessas frequências existem inúmeras restrições na propagação de sinais, então antenas com alto rendimento são necessárias para permitir comunicação com perdas reduzidas. A proposta desse trabalho é estudar algumas configurações e tipos de antenas, tais como de antena de microfita e antena dipolo, com aplicação na faixa de frequência em subterahertz, que podem ser utilizadas, por exemplo, nas redes internas, medicina, na geração de energia fotovoltaica, espectroscopia, microscopia de campo próximo e obtenção de imagens de alta qualidade. Serão apresentadas algumas configurações de antenas e com diversos materiais para comunicações na faixa de frequência em questão, para verificar a viabilidade do uso de nanoantenas de dipolo e de antenas de microfita miniaturizadas neste tipo de aplicação. A metodologia adotada sugere a comparação dos resultados simulados, através dos softwares Ansoft HFSS ® e CST Microwave Studio ®, com os resultados de outros trabalhos publicados / 2017-07-14

The studies in this dissertation mainly utilize planar antennas for ultra-wideband antenna designs not only on the investigation of antenna performance but also towards exploiting attractive features of ultra-wideband antennas for practical applications, such as WMAN access-point antennas, omnidirectional WiMAX access-point antennas, band-notched UWB (Ultra-wideband, 3.1 ~ 10.6 GHz) antennas, and so on. To begin with, the effects of the ground-plane size and the asymmetrical ground plane on ultra-wideband antennas are studied in Chapter 2. Following up, from the conclusive results, an antenna for WMAN operation in access-point applications and an omnidirectional monopole for USB wireless network card device are proposed and analyzed. Characteristics of ultra-wideband antenna radiation in relation to the antenna's width for obtaining omnidirectional radiation are addressed. In Chapter 3, several ultra-wideband access-point antennas are presented for achieving good omnidirectional radiation in the azimuthal plane across the bandwidth. Furthermore, in Chapter 4, band-notching techniques are applied to ultra-wideband antennas for avoiding the interference between the UWB and the WLAN systems.

This thesis presents various integrated antenna solutions for different types of systems and applications, e.g. wireless sensors, broadband handsets, advanced base stations, MEMS-based reconfigurable front-ends, automotive anti-collision radars, and large area electronics. For wireless sensor applications, a T-matched dipole is proposed and integrated in an electrically small body-worn sensor node. Measurement techniques are developed to characterize the port impedance and radiation properties. Possibilities and limitations of the planar inverted cone antenna (PICA) for small handsets are studied experimentally. Printed slot-type and folded PICAs are demonstrated for UWB handheld terminals. Both monolithic and hybrid integration are applied for electrically steerable array antennas. Compact phase shifters within a traveling wave array antenna architecture, on single layer substrate, is investigated for the first time. Radio frequency MEMS switches are utilized to improve the performance of reconfigurable antennas at higher frequencies. Using monolithic integration, a 20 GHz switched beam antenna based on MEMS switches is implemented and evaluated. Compared to similar work published previously, complete experimental results are here for the first time reported. Moreover, a hybrid approach is used for a 24 GHz switched beam traveling wave array antenna. A MEMS router is fabricated on silicon substrate for switching two array antennas on a LTCC chip. A concept of nano-wire based substrate integrated waveguides (SIW) is proposed for millimeter-wave applications. Antenna prototypes based on this concept are successfully demonstrated for automotive radar applications. W-band body-worn nonlinear harmonic radar reflectors are proposed as a means to improve automotive radar functionality. Passive, semi-passive and active nonlinear reflectors consisting of array antennas and nonlinear circuitry on flex foils are investigated. A new stretchable RF electronics concept for large area electronics is demonstrated. It incorporates liquid metal into microstructured elastic channels. The prototypes exhibit high stretchability, foldability, and twistability, with maintained electrical properties. / wisenet

Die vorliegende Arbeit untersucht die grundsätzliche Machbarkeit, Radiofrequenzimpulse (RF) der Ultrahochfeld (UHF) Magnetresonanztomographie (MRT) (B0≥7.0T) für therapeutische Verfahren wie die RF Hyperthermie oder die lokalisierte Freigabe von Wirkstoffträgern und Markern zu nutzen. Im Rahmen der Arbeit wurde ein 8-Kanal Sened/Empfangsapplikator entwickelt, der bei einer Protonenfrequenz von 298MHz operiert. Mit diesem weltweit ersten System konnte in der Arbeit experimentell bewiesen werden, dass die entwickelte Hardware sowohl zielgerichtete lokalisierte RF Erwärmung als auch MR Bildgebung und MR Thermometrie (MRTh) realisiert. Mit den zusätzlichen Freiheitsgraden (Phase, Amplitude) eines mehrkanaligen Sendesystems konnte aufgezeigt werden, dass der Ort der thermischen Dosierung gezielt verändert bzw. festgelegt werden kann. In realitätsnahen Temperatursimulationen mit numerischen Modellen des Menschen, wird in der Arbeit aufgezeigt, dass mittels des entwickelten Hybridaufbaus eine kontrollierte und lokalisierte thermische Dosierung im Zentrum des menschlichen Kopfes erzeugt werden kann. Nach der erfolgreichen Durchführung dieser Machbarkeitsstudie wurden in theoretischen Überlegungen, numerischen Simulationen und in ersten grundlegenden experimentellen Versuchen die elektromagnetischen Gegebenheiten von MRT und lokal induzierter RF Hyperthermie für Frequenzen größer als 298MHz untersucht. In einem Frequenzbereich bis zu 1.44GHz konnte der Energiefokus mit Hilfe spezialisierter RF Antennenkonfigurationen entscheidend weiter verkleinert werden, sodass Temperaturkegeldurchmesser von wenigen Millimetern erreicht wurden. Gleichzeitig konnte gezeigt werden, dass die vorgestellten Konzepte ausreichende Signalstärke der zirkular polarisierten Spinanregungsfelder bei akzeptabler oberflächlicher Energieabsorption erzeugen, um eine potentielle Machbarkeit von in vivo MRT bei B0=33.8T oder in vivo Elektronenspinresonanz (ESR) im L-Band zu demonstrieren. / The presented work details the basic feasibility of using radiofrequency (RF) fields generated by ultrahigh field (UHF) magnetic resonance (MR) (B0≥7.0T) systems for therapeutic applications such as RF hyperthermia and targeted drug delivery. A truly hybrid 8-channel transmit/receive applicator operating at the 7.0T proton MR frequency of 298MHz has been developed. Experimental verification conducted in this work demonstrated that the hybrid applicator supports targeted RF heating, MR imaging and MR thermometry (MRTh). The approach offers extra degrees of freedom (RF phase, RF amplitude) that afford deliberate changes in the location and thermal dose of targeted RF induced heating. High spatial and temporal MR temperature mapping can be achieved due to intrinsic signal-to-noise ratio (SNR) gain of UHF MR together with the enhanced parallel imaging performance inherent to the multi-channel receive architecture used. Temperature simulations in human voxel models revealed that the proposed hybrid setup is capable to deposit a controlled and localized RF induced thermal dose in the center of the human brain. After demonstrating basic feasibility, theoretical considerations and proof-of-principle experiments were conducted for RF frequencies of up to 1.44GHz to explore electrodynamic constraints for MRI and targeted RF heating applications for a frequency range larger than 298MHz. For this frequency regime a significant reduction in the effective area of energy absorption was observed when using dedicated RF antenna arrays proposed and developed in this work. Based upon this initial experience it is safe to conclude that the presented concepts generate sufficient signal strength for the circular polarized spin excitation fields with acceptable specific absorption rate (SAR) on the surface, to render in vivo MRI at B0=33.8T or in vivo electron paramagnetic resonance (EPR) at L-Band feasible.