This master's thesis is engage in suggestion of low noise 70 cm band amplifier with filter and diode attenuator. At first the thesis describes the basic parameters of amplifier, for example gain, noise figure and dynamic extent. Later in detail describes individual parts, which are the device consist of. At every part of system is mentioned the diagram of connection and values of components, which are ascertained from calculation, simulation and recommendation of producer. The characteristic parameters of amplifier were measured after construction.

Silicon carbide is a promising semiconductor material for high voltage, high frequency and high temperature devices due to its wide bandgap, high breakdown electric field strength, highly saturated drift velocity of electrons and outstanding thermal conductivity. With the aim of overcoming some challenges in metallization and doping during the fabrication of silicon carbide devices, a novel laser-based process is provided to direct metallize the surface of silicon carbide without metal deposition and dope in silicon carbide without high temperature annealing, as an alternative to the conventional ion implantation, and find applications of this laser direct write metallization and doping technique on the fabrication of diodes, endotaxial layer and embedded optical structures on silicon carbide wafers. Mathematical models have been presented for the temperature distributions in the wafer during laser irradiation to optimize laser process parameters and understand the doping and metallization mechanisms in laser irradiation process. Laser irradiation of silicon carbide in a dopant-containing ambient allows to simultaneously heating the silicon carbide surface without melting and incorporating dopant atoms into the silicon carbide lattice. The process that dopant atoms diffuse into the bulk silicon carbide by laser-induced solid phase diffusion (LISPD) can be explained by considering the laser enhanced substitutional and interstitial diffusion mechanisms. Nitrogen and Trimethyaluminum (TMA) are used as dopants to produce n-type and p-type doped silicon carbide, respectively. Two laser doping methods, i.e., internal heating doping and surface heating doping are presented in this dissertation. Deep (800 nm doped junction for internal heating doping) and shallow (200 nm and 450 nm doped junction for surface heating doping) can be fabricated by different doping methods. Two distinct diffusion regions, near-surface and far-surface regions, were identified in the dopant concentration profiles, indicating different diffusion mechanisms in these two regions. The effective diffusion coefficients of nitrogen and aluminum were determined for both regions by fitting the diffusion equation to the measured concentration profiles. The calculated diffusivities are at least 6 orders of magnitude higher than the typical values for nitrogen and aluminum, which indicate that laser doping process enhances the diffusion of dopants in silicon carbide significantly. No amorphization was observed in laser-doped samples eliminating the need for high temperature annealing. Laser direct metallization can be realized on the surface of silicon carbide by generating metal-like conductive phases due to the decomposition of silicon carbide. The ohmic property of the laser direct metallized electrodes can be dramatically improved by fabricating such electrodes on laser heavily doped SiC substrate. This laser-induced solid phase diffusion technique has been utilized to fabricate endolayers in n-type 6H-SiC substrates by carbon incorporation. X-ray energy dispersive spectroscopic analysis shows that the thickness of endolayer is about 100 nm. High resolution transmission electron microscopic images indicate that the laser endotaxy process maintains the crystalline integrity of the substrate without any amorphization. Rutherford backscattering studies also show no amorphization and evident lattice disorder occur during this laser solid phase diffusion process. The resistivity of the endolayer formed in a 1.55 omega•cm silicon carbide wafer segment was found to be 1.1E5 omega•cm which is sufficient for device fabrication and isolation. Annealing at 1000 oC for 10 min to remove hydrogen resulted in a resistivity of 9.4E4 omega•cm. Prototype silicon carbide PIN diodes have been fabricated by doping the endolayer and parent silicon carbide epilayer with aluminum using this laser-induced solid phase diffusion technique to create p-regions on the top surfaces of the substrates. Laser direct metallized contacts were also fabricated on selected PIN diodes to show the effectiveness of these contacts. The results show that the PIN diode fabricated on a 30 nm thick endolayer can block 18 V, and the breakdown voltages and the forward voltages drop at 100 A/cm2 of the diodes fabricated on 4H-SiC with homoepilayer are 420 ~ 500 V and 12.5 ~ 20 V, respectively. The laser direct metallization and doping technique can also be used to synthesize embedded optical structures, which can increase 40% reflectivity compared to the parent wafer, showing potential for the creation of optical, electro-optical, opto-electrical, sensor devices and other integrated structures that are stable in high temperature, high-pressure, corrosive environments and deep space applications.

Yes / In this paper, we present a simple reconfigurable multiband antenna with two PIN diode switches for WiMAX/WLAN applications. The antenna permits reconfigurable switching in up to ten frequency bands between 2.2 GHz and 6 GHz, with relative impedance bandwidths of around 2.5% and 8%. The proposed antenna has been simulated using CST microwave studio software and fabricated on an FR-4 substrate. It is compact, with an area of 50 × 45 mm2, and has a slotted ground substrate. Both measured and simulated return loss characteristics of the optimized antenna show that it satisfies the requirement of 2.4/5.8 GHz WLAN and 3.5 GHz WiMAX antenna applications. Moreover, there is good agreement between the measured and simulated result in terms of radiation pattern and gain. / Engineering and Physical Science Research Council through Grant EP/E022936A.

RF/Microwave switches are widely used in microwave measurement systems, telecommunication and radar applications. The main purposes of RF switches are Tx-Rx switching, band select and switching the signal between different paths. Thus, they are key circuits especially in T/R modules. Wideband operation is an important criterion in EW applications. High power handling is also a key feature especially for radars detecting long range. In this study, different types of high power solid state switches operating at X-Band are designed, fabricated and measured. The main objectives are small size and high power handling while keeping good return loss and low insertion loss. The related studies are investigated and analyzed. Solutions for increasing the power handling are investigated, related calculations are done. Better bias conditions are also analyzed. The measurement results are compared with simulations and analysis. Circuit designs and simulations are performed using AWR&reg / and CST&reg / .

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19722号 / 工博第4177号 / 新制||工||1644(附属図書館) / 32758 / 京都大学大学院工学研究科電子工学専攻 / (主査)教授 木本 恒暢, 教授 髙岡 義寛, 教授 山田 啓文 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

The purpose of this project was to design, construct, and evaluate an alpha spectrometer based on an inexpensive p-i-n photodiode as a radiation detector. The BPX-61 p-i-n photodiode was selected and calculated to have a 93 µm wide sensitive volume at 25 V reverse bias. Electronics consisting of a charge-sensitive preamplifier, a pole-zero canceling CR-(RC)4 pulse shaping amplifier, and an adjustable detector bias voltage supply were devised and assembled. Several alpha spectra were recorded from different alpha radiation sources to determine the performance of the alpha spectrometer. The results show that the alpha spectrometer could successfully and accurately measure alpha spectra, which could then be used to identify radioactive materials present in the sources. An FWHM resolution of about 230 keV was measured for 5.486 MeV alpha particles from Am-241. This resolution is inferior to most alpha spectrometers that measure under vacuum. However, because the device does not require a vacuum pump and uses USB for power and data acquisition, it is a convenient and compact option for field measurements. The low cost and reasonable performance of commercial p-i-n photodiodes as radiation detectors could be appealing for future alpha spectroscopy applications.

The objectives of this work were to investigate, design and implement beam steering antenna arrays for mobile and wireless applications using the genetic algorithm (GA) and particle swarm optimisation (PSO) techniques as optimisation design tools. Several antenna designs were implemented and tested: initially, a printed dipole antenna integrated with a duplex RF switch used for mobile base station antenna beam steering was investigated. A coplanar waveguide (CPW) to coplanar strip (CPS) transition was adopted to feed the printed dipole. A novel RF switch circuit, used to control the RF signal fed to the dipole antenna and placed directly before it, was proposed. The measured performance of the RF switch was tested and the results confirmed its viability. Then two hybrid coupled PIN diode phase shifters, using Branchline and Rat-Race ring coupler structures, were designed and tested. The generation of four distinct phase shifts was implemented and studied. The variations of the scattering parameters were found to be realistic, with an acceptable ±2 phase shift tolerance. Next, antenna beam steering was achieved by implementing RF switches with ON or OFF mode functions to excite the radiating elements of the antenna array. The switching control process was implemented using a genetic algorithm (GA) method, subject to scalar and binary genes. Anti-phase feeding of radiating elements was also investigated. A ring antenna array with reflectors was modelled and analysed. An antenna of this type for mobile base stations was designed and simulation results are presented. Following this, a novel concept for simple beam steering using a uniform antenna array operated at 2.4 GHz was designed using GA. The antenna is fed by a single RF input source and the steering elements are reactively tuned by varactor diodes in series with small inductors. The beam-control procedure was derived through the use of a genetic algorithm based on adjusting the required reactance values to obtain the optimum solution as indicated by the cost function. The GA was also initially used as an optimisation tool to derive the antenna design from its specification. Finally, reactive loading and time modulated switching techniques are applied to steer the beam of a circular uniformly spaced antenna array having a source element at its centre. Genetic algorithm (GA) and particle swarm optimisation (PSO) processes calculate the optimal values of reactances loading the parasitic elements, for which the gain can be optimised in a desired direction. For time modulated switching, GA and PSO also determine the optimal on and off times of the parasitic elements for which the difference in currents induced optimises the gain and steering of the beam in a desired direction. These methods were demonstrated by investigating a vertically polarised antenna configuration. A prototype antenna was constructed and experimental results compared with the simulations. Results showed that near optimal solutions for gain optimisation, sidelobe level reduction and beam steering are achievable by utilising these methods. In addition, a simple switching process is employed to steer the beam of a horizontally polarised circular antenna array. A time modulated switching process is applied through Genetic Algorithm optimisation. Several model examples illustrate the radiation beams and the switching time process of each element in the array.

Phase shifters are common microwave circuit devices, which are widely used in telecommunication and radar applications, microwave measurement systems, and many other industrial applications. They are key circuits of T/R modules and are used to form the main beam of the electronically scanned phase array antennas. Wideband operating range is an important criterion for EW applications. Hence, wideband performance of the phase shifter is also important. In this study, four wideband phase shifter circuits are designed, fabricated and measured for 6-18 GHz frequency range. Phase shifters are separately designed in order to get 11.25, 22.5, 45 and 90&ordm / phase shifts with minimum phase error and low return losses. Phase shifter circuits are designed and fabricated in microstrip structure onto two different substrates as Rogers TMM10i and Alumina using printed circuit board and thin film production techniques, respectively. Also phase shifter circuits that include microstrip spiral inductors for DC biasing are designed and fabricated using thin film production technique. For each design the fabricated circuits are measured and results are compared with simulation results in the content of this thesis. Circuit designs and EM simulations are performed by using ADS2008&reg / , Sonnet&reg / , and CST&reg / .

Wireless and mobile communications are already playing an important role in our lives, and this will can only grow more and more due to the predominant importance and use of modern smartphones, tablets and any kind of connected devices. With this is mind, the spectrum for wireless and mobile communications is becoming incredibly overcrowded, leading to increasing requirements for RF front-end filters. This progress has encouraged an impressive need for developing low-cost, high performance, mass-producible, small footprint, and highly integrated front-end solutions for microwave and millimeter-wave systems and applications including emerging 5G and future wireless platforms. In this context, high quality factor resonators are usually typical basic building blocks of many high performance passive and active circuits, and its design has become even more challenging in the last decade. As a result, Substrate Integrated Waveguide (SIW) technology has attracted scientific community and industry attention as a very good candidate for developing such desired high-Q planar microwave devices. Recently, SIW is demonstrating to be a successful approach for implementing microwave and mm-wave filters with high Q-factor, easy integration with other planar circuits, and for mass-production manufacturing processes in many technologies (i.e. Printed Circuit Board (PCB) and Low Temperature Co-fired Ceramics (LTCC) technologies among them). Its enormous similarity with waveguides is probably one of the main reasons why the development of SIW-based components and circuits is rapidly growing among the research community. Other potential features that, combined with the former advantages, could be of huge interest in a wide range of wireless and mobile applications are a lively set of research subjects, such as compactness, advanced filtering responses, and recently frequency-agility capabilities. These key features have been recently introduced in the design of microwave filters for the next-generation wireless systems. Taking into account the above-mentioned background, the work carried out during the course of this PhD Thesis has been directed towards a further study of SIW technology to propose, analyze and develop an innovative and original resonator topology. The proposed topology is based on the extension of the classical coaxial waveguide resonator to SIW technology, and must take advantage of the characteristics of SIW devices to allow the design of improved and innovative microwave resonator filters for advanced wireless systems. This PhD Thesis includes the latest improvements made on this topic, from the working principles of the basic coaxial SIW block, until different applications for the design of compact quasi-elliptic and reconfigurable microwave filters. The results are promising and demonstrate the validity of the proposed topology for the design of high-Q microwave filters, as well as its potential application to implement complex designs. The general knowledge gained from these cases of study can be considered a good base for further developing this technology, which can help to improve its EM performance, and also contribute to a more general use in the market. / Las comunicaciones inalámbricas y móviles juegan un papel importante en nuestras vidas, y esto sólo puede ir a más debido a su enorme importancia y al uso de los modernos teléfonos inteligentes (del inglés, smartphones), tabletas y toda clase de dispositivos inalámbricos. Con todo esto en mente, el espectro electromagnético para comunicaciones inalámbricas y móviles se está saturando cada día más, lo que conlleva un constante aumento de los requisitos para los filtros de radio-frecuencia usados en las cabeceras de dichos sistemas. Este progreso ha llevado a un creciente interés en desarrollar componentes de microondas de bajo coste, alto rendimiento, pequeño tamaño, que permitan implementar soluciones altamente integradas para sistemas de alta frecuencia (i.e. microondas y ondas milimétrica) y sus aplicaciones, incluyendo entre ellas la emergente conexión 5G y las futuras plataformas inalámbricas. En este contexto, los resonadores de elevado factor de calidad constituyen generalmente los bloques básicos para el diseño de muchos circuitos pasivos (entre ellos filtros) y activos de alto rendimiento. Su diseño se ha convertido por tanto en un reto aún mayor en la última década. Como resultado de ello, la tecnología de guía de ondas integradas en substrato (Substrate Integrated Waveguide, SIW) ha atraído la atención de la comunidad científica e industrial, al revelarse como una buena aproximación para el desarrollo de dispositivos planares de microondas con excelentes prestaciones eléctricas, y en particular para la implementación de filtros de microondas y onda milimétrica de bajas pérdidas y elevada integración con circuitos en tecnología planar. Además, su flexibilidad se caracteriza también por su adecuación a diferentes procesos de fabricación y producción en masa, en tecnologías tales como los circuitos impresos (Printed Circuit Board, PCB) o la tecnología de materiales cerámicos multi-capa co-sinterizados a baja temperatura (Low Temperature Co-fired Ceramics, LTCC) entre otras. Su enorme similitud con las ya largamente estudiadas guías de onda es, probablemente, una de las principales razones por las cuales el desarrollo de dicho circuitos está creciendo rápidamente entre la comunidad de investigadores. Cabe mencionar como, además de las anteriores ventajas, otras características de la tecnología SIW que podrían ser de gran interés en una amplia gama de aplicaciones inalámbricas y móviles son la miniaturización, la posibilidad de implementar respuestas avanzadas de filtrado y, recientemente, las capacidades de sintonía en frecuencia de los componentes de microondas. De este modo, el trabajo desarrollado a lo largo de esta Tesis Doctoral se ha orientado hacia el planteamiento, análisis y desarrollo de una topología de resonador innovadora y original. Dicha topología se basa en una extensión de las cavidades coaxiales en guía de onda metálica a una implementación integrada en substrato inspirada en la tecnología SIW. Esta Tesis Doctoral recapitula los últimos avances que se han producido sobre este tema, empezando desde la descripción de los principios fundamentales de funcionamiento de las estructuras, hasta la demostración de varias aplicaciones concretas útiles para el diseño de filtros de microondas muy compactos, con respuestas filtrantes avanzadas y reconfigurables. Los resultados que se van a mostrar a continuación son prometedores, y demuestran la validez de la topología propuesta. El conocimiento general obtenido de los diferentes prototipos fabricados y caracterizados experimentalmente puede considerarse una buena base para seguir desarrollando esta tecnología, lo que puede ayudar a mejorar su rendimiento electromagnético, así como a contribuir a un uso más extendido de estos dispositivos en el mercado. / Les comunicacions sense fils i mòbils juguen un paper important en les nostres vides, i això només pot anar a més a causa de la gran importància i l'ús dels moderns telèfons intel·ligents (de l'anglès, smartphones), tablets i tota classe de dispositius sense fil. Tenint en compte tot açò, l'espectre electromagnètic per a comunicacions sense fils i mòbils s'està saturant cada dia més, el que comporta un constant augment dels requisits per als filtres de radiofreqüència usats en les capçaleres d'aquests sistemes. Aquest progrés ha portat a un creixent interès en desenvolupar components de microones de baix cost, alt rendiment, volum reduït, que permeten implementar solucions altament integrades per a sistemes d'alta freqüència (ie. microones i ones mil·limètriques) i les seves aplicacions, incloent l'emergent connexió 5G i les futures plataformes sense fils. En aquest context, els ressonadors d'elevat factor de qualitat constitueixen generalment els blocs bàsics per al disseny de molts circuits passius (entre ells filtres) i actius d'alt rendiment. El seu disseny s'ha convertit per tant en un repte encara més gran en l'última dècada. Com a resultat d'això, la tecnologia de guia d'ones integrades en substrat (Substrate Integrated Waveguide, SIW) ha atret l'atenció de la comunitat científica i industrial, al revelar-se com una bona aproximació per al desenvolupament de dispositius planars de microones amb excel·lents prestacions elèctriques , i en particular per a la implementació de filtres de microones i ones mil·limètriques de baixes pèrdues i elevada integració amb circuits en tecnologia planar. A més, la seua flexibilitat es caracteritza també per la seua adequació a diferents processos de fabricació i producció en massa, en tecnologies com ara els circuits impresos (Printed Circuit Board, PCB) o la tecnologia de materials ceràmics multicapa co-sinteritzats a baixa temperatura (Low Temperature Co-Fired Ceramics, LTCC) entre d'altres. La seua enorme similitud amb les ja llargament estudiades guies d'ona és, probablement, una de les principals raons per les quals el desenvolupament d'aquests circuits està creixent ràpidament entre la comunitat d'investigadors. Cal destacar com, a més de les anteriors avantatges, altres característiques de la tecnologia SIW que podrien ser de gran interès en una àmplia gamma d'aplicacions sense fils i mòbils són la miniaturització, la possibilitat d'implementar respostes avançades de filtrat i, recentment, les capacitats de sintonia en freqüència dels components de microones. Aquestes característiques clau s'han introduït recentment en el disseny de filtres microones per als sistemes sense fils de pròxima generació, convertint-se en objecte prioritari d'estudi per part de la comunitat científica. D'aquesta manera, el treball desenvolupat al llarg d'aquesta tesi doctoral s'ha orientat cap al plantejament, anàlisi i desenvolupament d'una topologia de ressonador innovadora i original. Aquesta topologia es basa en una extensió de les cavitats coaxials en guia d'ona metàl·lica a una implementació integrada a substrat inspirada en la tecnologia SIW. Aquesta tesi doctoral recapitula els últims avanços que s'han produït sobre aquest tema, començant des de la descripció dels principis fonamentals de funcionament de les estructures, fins a la demostració de diverses aplicacions concretes útils per al disseny de filtres i microones molt compactes, amb respostes de filtrat avançades i reconfigurables. Els resultats que es mostraran a continuació són prometedors, i demostren la validesa de la topologia proposada. El coneixement general obtingut dels diferents prototips fabricats i caracteritzats experimentalment es pot considerar com una bona base per seguir desenvolupant aquesta tecnologia, el que pot ajudar a millorar el seu rendiment electromagnètic, així com a contribuir a un ús més estès d'aquests dispositius en el mer / Sirci, S. (2017). Substrate Integrated Coaxial Filters with Fixed and Tunable Responses [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/78838 / TESIS

Radio frequency (RF) and microwave switches are widely used in several different applications including radar, measurement systems, telecommunications, and other areas. An RF switch can control a radar’s transmit vs. receive mode, select the operating band, or direct an RF signal to different paths. In this study, a single pole eight throw (SP8T) switch using only Surface Mount (SMT) components is designed and simulated in Keysight’s Advanced Design System (ADS). Single pole eight throw is defined as one input and eight possible outputs. A star network configuration with series-shunt PIN diode switches is used to create the 8-way RF switch. There are other commercially available SP8T switches from MACOM, Skyworks, Analog Devices, and other vendors that operate around this bandwidth. However, this design uses SMT components and series-shunt diode configurations to create a device in the GHz range and power handling in the high 20 to 30 dBm range. This study modeled components in ADS, including the PIN diodes and the bias tees. The project also analyzed multiple layouts, finalizing the optimal design to meet specifications. The insertion loss, bandwidth, isolation, return loss, power handling, and switching speed are analyzed in the final design. Key specifications for this design are determined by comparing to other commercially available SP4T and SP8T switches from MACOM, Skyworks, Analog Devices, and other vendors, as well as developing an operational switch over the 2-18 GHz bandwidth. Additional specifications include limiting insertion loss to 2.0 dB maximum and maximizing isolation to 30 dB minimum. Switching speed and power handling specifications are also set to 20 ns and 23 dBm, respectively. Future projects will work on design fabrication and improvements to the manufactured switch.