This thesis proposes a novel dual passband filter architecture and develops a design flow and synthesis method for this architecture. The technical contents include the fundamental passband filter design and the further methods for generating the higher second passband and the multiple transmission zeros. This thesis organizes a design flow based on analytical formulation for the proposed dual passband filter architecture. One can follow this design flow to substitute the filter specifications into the formulation and then can obtain the necessary element values for the filter architecture that match the specified specifications. The dual passband filter architecture is finally implemented on LTCC substrate for WLAN (IEEE 802.11 a/b/g) applications with verification of S parameters using EM-simulation and actual measurement.

In the thesis, we use the concept of single-negative metamaterials to reduce the antennas¡¦ coupling. Firstly, the multilayer insulator is proposed to enhance the isolation bandwidth. The isolation bandwidth is broadened by adjusting the individual layer of insulators with close but different operating frequencies. Then, the designed multilayer insulator is inserted in a planar antenna system. Isolation of the MIMO antenna system is below than -20dB. The measured and simulated isolation bandwidth is 8% and 6.9%, respectively. We then design dual-band insulators for dual-band MIMO antenna applications. The proposed dual-band insulator is implemented bystacking the insulators with different operating bands and the isolation of the dual-band MIMO antenna can be improved at both 2.6 and 3.5GHz bands. In the broadband insulator design, the T-shaped branch is proposed to broadenthe operating bandwidth. The measured isolation bandwidth is improved by 12.8% than that of the multilayer insulator. The bandwidth of the proposed broadband insulator can be used in other broadband communication standards.

This dissertation investigates the use of the harmonic radar technique for passive wireless sensing applications. Issues of DC power consumption, high RF activation power, large node size, and short communication range associated with the existing passive wireless sensing technologies are addressed by the development of novel, completely passive, high efficiency, compact 3-D harmonic sensor nodes. The node transceiver employs a passive frequency doubler to return the second harmonic of the interrogation signal, and electrically-small 3-D antennas to achieve the compactness and high efficiency. The developed nodes fit inside a sphere with a diameter < 3 cm and achieve communication range > 60 m using a 43 dBm EIRP interrogator. Effective modulation is demonstrated experimentally using low cost commercial vibration sensors. To address major challenges associated with long-range, embedded, passive wireless sensing including sensor node identification and remote channel calibration, a 3-D dual-channel transceiver is developed. To the best of the author's knowledge, the presented dual-channel transceiver is the first completely passive design with built-in passive remote channel calibration and identification capabilities, and the presented nodes have the best overall performance among previously published designs, in terms of conversion efficiency, communication range, and occupied volume. To reduce the cost and weight and improve the manufacturing process of the proposed nodes, the 3-D digital additive manufacturing and conformal direct printing technologies are employed. The harmonic interrogator antenna design is also an underlying focus of this work. Different interrogator antenna candidates are developed based on different design approaches. The first approach is based on the use of dual-channel antenna array, where one channel is used for transmission and the second channel is used for reception. Two dual-channel harmonic interrogator antennas that consist of 4-element circular patch antenna arrays and 2-element quasi-Yagi dipole antenna arrays are implemented. The second approach employs mechanically reconfigurable antennas to reduce the size and maintain persistent radiation properties over wide frequency bandwidth. Two mechanical reconfiguration methods are developed; the first method is based on the use of Hoberman's planar foldable linkage to vary the operating frequency of planar circular patch antennas and the second mechanical reconfiguration method is based on the use of a rack and pinion mechanism to reconfigure dual-band slot antennas. The third approach employs a single channel multi-octave Vivaldi antenna to provide the capability to interrogate a large number of harmonic tags that are widely spaced in frequency. To improve the antenna radiation performance over a broad frequency range, a new method based on the introduction of a parasitic elliptical patch in the flare aperture is proposed. This method enables gain and bandwidth improvement compared to what has been reported for Vivaldi antennas with a compact size. To provide the interrogator the capability to steer the radiation beam for locating and tracking sensor nodes, a topology to develop a miniature, non-dispersive switchable 4-bit phase shifter is proposed on the basis of composite right/left handed transmission line unit cells.

ITC/USA 2012 Conference Proceedings / The Forty-Eighth Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2012 / Town and Country Resort & Convention Center, San Diego, California / A new common aperture autotracking C-band feed, specifically designed to accurately track fast moving targets such as the Lance missile, is reviewed. Measured data demonstrates exceptional tracking modulation required for good tracking performance while simultaneously providing excellent data channel performance for high G/T over the entire 4.40-5.25 GHz band. The new patent applied for feed design allows users to maintain existing L/S-band capability with a cost effective field upgrade which adds high performance C-band capability to an existing telemetry tracking system.

In wireless communication systems, multiple standards have been implemented to meet the past and present demands of different applications. This proliferation of wireless standards, operating over multiple frequency bands, has increased the demand for radio frequency (RF) components, and consequently power amplifiers (PA) to operate over multiple frequency bands. In this research work, a systematic approach for the synthesis of a novel dual-band matching network is proposed and applied for effective design of PA capable of maintaining high power efficiency at two arbitrary widely spaced frequencies. The proposed dual-band matching network incorporates two different stages. The first one aims at transforming the targeted two complex impedances, at the two operating frequencies, to a real one. The second stage is a dual-band filter that ensures the matching of the former real impedance to the termination impedance to 50 Ohm. Furthermore, an additional transmission line is incorporated between the two previously mentioned stages to adjust the impedances at the second and third harmonics without altering the impedances seen at the fundamental frequencies. Although simple, the harmonic termination control is very effective in enhancing the efficiency of RF transistors, especially when exploiting the Class J design space. The proposed dual-band matching network synthesis methodology was applied to design a dual-band power amplifier using a packaged 45 W gallium nitride (GaN) transistor. The power amplifier prototype maintained a peak power efficiency of about 68% at the two operating frequencies, namely 800 MHz and 1.9 GHz. In addition, a Volterra based digital predistortion technique has been successfully applied to linearize the PA response around the two operating frequencies. In fact, when driven with multi-carrier wideband code division multiple access (WCDMA) and long term evolution (LTE) signals, the linearized amplifier maintained an adjacent channel power ratio (ACPR) of about 50 dBc and 46 dBc, respectively.

The physics and technology of the heterojunction infrared photodetectors having different material systems have been studied extensively. Devices used in this study have been characterized by using mainly optical methods, and electrical measurements have been used as an auxiliary method. The theory of internal photoemission in semiconductor heterojunctions has been investigated and the existing model has been extended by incorporating the effects of the difference in the effective masses in the active region and the substrate, nonspherical-nonparabolic bands, and the energy loss per collisions. The barrier heights (correspondingly the cut-off wavelengths) of SiGe/Si samples have been found from their internal photoemission spectrums by using the complete model which has the wavelength and doping concentration dependent free carrier absorption parameters. A qualitative model describing the mechanisms of photocurrent generation in SiGe/Si HIP devices has been presented. It has been shown that the performance of our devices depends significantly on the applied bias and the operating temperature. Properties of internal photoemission in a PtSi/Si Schottky type infrared detector have also been studied. InGaAs/InP quantum well photodetectors that covers both near and mid-infrared spectral regions by means of interband and intersubband transitions have been studied. To understand the high responsivity values observed at high biases, the gain and avalanche multiplication processes have been investigated. Finally, the results of a detailed characterization study on a systematic set of InAs/GaAs self-assembled quantum dot infrared photodetectors have been presented. A simple physical picture has also been discussed to account for the main observed features.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-03-08T12:15:41Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DissertaçãoDaviLira.pdf: 3636018 bytes, checksum: a3d66cf7d5a7e3e102b2d49abcabf422 (MD5) / Made available in DSpace on 2017-03-08T12:15:41Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DissertaçãoDaviLira.pdf: 3636018 bytes, checksum: a3d66cf7d5a7e3e102b2d49abcabf422 (MD5) Previous issue date: 2016-04-13 / O presente trabalho introduz um novo método para confecção de acopladores híbridos do tipo branch-line que sejam de banda dupla, ou seja, que são projetados para operar em duas frequências desejadas quaisquer com a mesma resposta. Este método faz uso de uma nova estrutura de linha de transmissão artificial (LTA) implementada em microfita, a qual é composta por três linhas de transmissões conectadas em cascata, com estubes em aberto inseridos em paralelo entre as linhas de transmissão. Foram obtidas expressões algébricas que determinam, em função das frequências das bandas desejadas, os valores de impedância característica e comprimento elétrico de cada um dos segmentos e estubes para que, em ambas as frequências, a LTA tenha os mesmos parâmetros de espalhamento que, e portanto seja equivalente a, um único segmento de linha de transmissão convencional com impedância característica e comprimento elétrico quaisquer especificados. Para obter o acoplador híbrido do tipo branch-line com banda dupla, portanto, substituímos cada linha de transmissão do acoplador por uma ATL com os parâmetros calculados de acordo com as expressões encontradas. Essa técnica foi usada para projetar, simular, fabricar e medir um acoplador híbrido branch-line que funcionasse nas frequências GSM de 925MHz e ISM 5.8GHz. Essa técnica tem como principal vantagem a capacidade e a flexibilidade de obter acopladores branch-line com bom desempenho em duas bandas quaisquer. / This work deals with a new method for the design of dual band branch-line hybrid couplers with arbitrary central frequencies, in other words, branch-line couplers which operate in two desired frequencies. This method makes use of a new artificial transmission line (ATL) structure, which is composed of the cascade connection of three transmission lines segments with parallel open stubs between them. Algebraic expressions were obtained that specify, in function of the central frequencies, the values for the characteristic impedance and electric length of the segments, so that the ATL has, for both frequencies, the same scattering parameters, hence the same behavior, as an ordinary transmission line with any chosen characteristic impedance and electric length. To obtain a dual band branch line coupler, the desired frequencies are chosen and the expressions are evaluated to find out the characteristic impedances and electric lengths of the ATL’s to replace all transmission lines that make up the coupler. This technique was used to design, simulate, fabricate and measure a branch-line hybrid coupler that works on the 925MHz GSM and 5.8GHz ISM frequencies. This technique has as it’s main advantage the ability and flexibility to yield couplers with good performance in two arbitrary bands.

Orientadores: Francisco José Arnold, Leonardo Lorenzo Bravo Roger / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Tecnologia / Made available in DSpace on 2018-08-19T21:46:41Z (GMT). No. of bitstreams: 1 Grilo_Marcus_M.pdf: 4359440 bytes, checksum: 6cae50e622550385b3c928f7055ed0fe (MD5) Previous issue date: 2012 / Resumo: Este trabalho apresenta a análise, o projeto e a construção de uma antena de banda dupla para as faixas de frequências de 915MHz e 2,45GHz, para aplicação em sistemas RFID. A antena é impressa em um substrato de fibra de vidro e possui estrutura dipolar. Os elementos radiadores estão em faces opostas do substrato o que resulta em baixa capacitância do dispositivo. As simulações computacionais, realizadas no programa HFSS, apresentaram boa concordância com os resultados experimentais. Os resultados mostraram importantes vantagens conseguidas com a antena desenvolvida, tais como estrutura simples e independência e facilidade de sintonia. Além disso, os parâmetros característicos (perda de retorno e ganho) de desempenho da antena são bastante satisfatórios. Propostas para trabalhos futuros também são apresentadas / Abstract: This paper presents the analysis, design and construction of a dual band antenna for the frequency bands 915 MHz and 2.45 GHz, for use in RFID systems. The antenna is printed on a substrate of fiberglass and has a dipolar structure. The radiator elements are on opposite faces of the substrate which results in low capacitance of the device. Computer simulations, carried out in the program HFSS, in good agreement with experimental results. The results showed important advantages achieved with the antenna developed, such as simple structure, independence and ease of tuning. Moreover, the characteristic parameters (return loss and gain) antenna performance are quite satisfactory. Proposals for future work are also presented / Mestrado / Tecnologia e Inovação / Mestre em Tecnologia

The main goal of the masters project is to design a dual band antenna for receiving DVB-T signal in the area of the city of Brno. The antenna will be designed and detaily adjusted for receiving multiplex 1 and 3, exactly for frequencies of 538 MHz and 778 MHz. The designed antenna will be deeply tested in 4nec2 and CST Microwave Studio programs.

The extensive industrialization and human expansion has caused environmental protection wildlife conservation to become paramount concerns of the 21st century. The ecosystems of oceans and seas have particularly been affected due to activities like oil spills and increased fishing. This has led to a growing interest in monitoring of the oceans and marine animals to detect signs of distress in aquatic species. However, acquisition of data from oceans to land has been a challenging and expensive task. The concept of Internet of Sea provides a solution to this data transfer between the ocean nodes, like animal tags or deployed floating transceivers, and our land Internet, and can potentially eliminate the need of expensive monitoring ships or underwater cables. The Internet of Sea is system that comprises of sensor nodes in the form of detachable marine animal tags as the data acquisition platforms and distributed floating transceivers as the intermedium nodes which then transfer the data to the base-stations located on lands. The data acquired by animal tags are first to be stored in the tag, and once the tag comes to the sea surface, the data is transferred to the nearby floating transceivers. The floating transceivers have multi- hopping capability so the data can be passed to the land base-stations through a small number of transceivers. Due to the specific geometric shapes and size constraints of the tag and floating transceivers, as well as the harsh ocean environment, novel integrated antennas are required for this type of system. In this thesis, we propose several antenna designs suitable for Internet of Sea applications. The first design is a quasi-isotropic Antenna in Package (AiP), operating in the Bluetooth band, which has been designed for semi-real-time monitoring. Secondly, a large frequency-ratio dual- band microstrip antenna array, working at Extended Global System for Mobile communications (E-GSM900), Long Range (LoRa), and Bluetooth bands, has been designed for large-area wireless communication. Lastly, a circularly polarized microstrip antenna array has also been designed for Global Positioning System (GPS). Throughout the work, the measured results are consistent with the design strategies and simulation results.