Method of electronic beam steering for circular switched parasitic dipole arrays

This paper presents a method of electronic beam steering for a smart antenna system based on a switched parasitic array. The antenna system is made up of circular array of half wave dipoles, with four parasitic elements positioned equidistantly, surrounding one active central element. All parasitic elements are assumed to be switched between short-circuit and opencircuit states to change their resonant length. The switching between parasitic elements’ states is attained by connecting a switch that assumes ON/OFF states at the centre of each parasitic element. This allows some parasitic elements to act as reflectors while shortcircuited, whereas other parasitic elements act as directors when open-circuited. Thus, the direction of maximum gain is controlled by open- and shortcircuiting the parasitic elements. By appropriately selecting correct combination of short- and opencircuited parasitic elements together with the active element, a set of radiation patterns is formed covering the horizontal plane. Results for the horizontal coverage are presented with the main beam(s) directed at 00, 900, 1800, and/or 2700, as well as for an omnidirectional configuration resemblance. It is expected that increasing the number of parasitic elements will improve directional properties further

Antenna Designs for 5G/IoT and Space Applications

This book is intended to shed some light on recent advances in antenna design for these new emerging applications and identify further research areas in this exciting field of communications technologies. Considering the specificity of the operational environment, e.g., huge distance, moving support (satellite), huge temperature drift, small dimension with respect to the distance, etc, antennas, are the fundamental device allowing to maintain a constant interoperability between ground station and satellite, or different satellites. High gain, stable (in temperature, and time) performances, long lifecycle are some of the requirements that necessitates special attention with respect to standard designs. The chapters of this book discuss various aspects of the above-mentioned list presenting the view of the authors. Some of the contributors are working strictly in the field (space), so they have a very targeted view on the subjects, while others with a more academic background, proposes futuristic solutions. We hope that interested reader, will find a fertile source of information, that combined with their interest/background will allow efficiently exploiting the combination of these two perspectives

Antenas setoriais para sistemas de localização em redes de sensores sem fios

Doutoramento em Engenharia EletrotécnicaThis work investigates low cost localization systems (LS) based on received signal strength (RSS) and integrated with different types of antennas with main emphasis on sectorial antennas. The last few years have witnessed an outstanding growth in wireless sensor networks (WSN). Among its various possible applications, the localization field became a major area of research. The localization techniques based on RSS are characterized by simplicity and low cost of integration. The integration of LS based on RSS and sectorial antennas (SA) was proven to provide an effective solution for reducing the number of required nodes of the networks and allows the combination of several techniques, such as RSS and angle of arrival (AoA). This PhD thesis focuses on studying techniques, antennas and protocols that best meet the needs of each LS with main focus on low cost systems based on RSS and AoA. Firstly there are studied localization techniques and system that best suit the requirements of the user and the antennas that are most appropriate according to the nature of the signal. In this step it is intended to provide a fundamental understanding of the undertaken work. Then the developed antennas are presented according to the following categories: sectorial and microstrip antennas. Two sectorial antennas are presented: a narrowband antenna operating at 2.4 to 2.5 GHz and a broadband antenna operating at 800MHz-2.4GHz. The low cost printed antennas were designed to operate at 5 GHz, which may be used for vehicular communication. After presenting the various antennas, several prototypes of indoor/outdoor LS are implemented and analyzed. Localization protocols are also proposed, one based on simplicity and low power, and the other on interoperability with different types of antennas and system requirements.O presente trabalho investiga sistemas de localização (SL) de baixo custo baseados na intensidade do sinal (RSS) e integrados com diferentes tipos de antenas com principal destaque para antenas sectoriais. Os últimos anos testemunharam um crescimento surpreendente de redes de sensores sem fios (RSSF), onde entre diversas aplicações possíveis, a localização tornou-se uma das principais áreas de pesquisa. Técnicas baseadas na intensidade do sinal caracterizam-se pela simplicidade e baixo custo de integração. A integração de SL baseados na intensidade do sinal recebido e antenas sectoriais (AS) oferecem uma solução eficaz para reduzir o número de nós necessários e para combinar diversas técnicas de localização. Esta tese de doutoramento foca-se no estudado de técnicas, antenas e protocolos de acordo com os requisitos de cada sistema localização com especial atenção para sistemas de baixo custo baseados na intensidade do sinal e no ângulo de chegada. Inicialmente são estudadas técnicas e SL de acordo com as necessidades do utilizador e as antenas que melhor se enquadram de acordo com a natureza do sinal. Esta etapa tem como objectivo proporcionar a compreensão fundamental do trabalho desenvolvido. Em seguida são apresentadas as antenas desenvolvidas divididas em: antenas sectorias e antenas impressas de baixo custo. Duas antenas sectoriais são apresentadas: uma de banda estreita a operar a 2,4-2,5GHz e outro de banda larga 800MHz-2.4GHz. As antenas impressas foram desenvolvidas para operar a 5 GHz, pelo que podem ser utilizadas para comunicação veicular. Após apresentação das diversas antenas vários protótipos de SL interiores/exteriores são implementados e analisados. Protocolos de localização são também propostos, um baseado na simplicidade e baixo consumo, outro na interoperabilidade com diferentes tipos de antenas e requisitos do sistema

Modificação das caraterísticas de radiação de uma antena usando componentes eletrónicos

Ao longo das últimas décadas, a acentuada evolução tecnológica apresentou um papel fundamental no desenvolvimento das forças militares no mundo. O Exército português também assimilou esses avanços tecnológicos e incorporou-os nas suas atividades, originando uma revolução no modus operandi das Forças Armadas, designada por Revolução nos Assuntos Militares. Nos últimos anos, o Exército Português desenvolveu dois robôs para realizarem tarefas de vigilância e reconhecimento, nos vários teatros de operações. As comunicações sem fios com estes robôs necessitam de uma antena que seja robusta, de pequenas dimensões, e que permita variar a direção e largura do lobo principal. Foi assim dimensionada e simulada uma antena designada por Electronically Steerable Parasitic Array Radiator (ESPAR), através da técnica dos algoritmos genéticos, cujo projeto constitui o objetivo principal desta Dissertação de Mestrado. Esta antena vai possibilitar ao operador ter uma antena orientável, permitindo escolher a direção para a qual a emissão apresenta um ganho máximo. A variação das impedâncias mútuas da antena permite alterar a relação das correntes, que por sua vez torna possível variar a direção e largura de banda do lobo principal, possibilitando obter diferentes diagramas de radiação. A antena foi projetada e simulada para operar na banda dos 2,4GHz usando o programa 4NEC2X. Posteriormente, foi dimensionada uma malha de adaptação e um plano de terra que permitiram assegurar a adaptação e funcionamento eficaz da antena. A antena ESPAR, pelas suas caraterísticas finais, apresenta os requisitos necessários para estabelecer comunicação com os robôs, nos teatros de operações do Exército Português.Over the past few decades, the increased technological growth has played a key role in the development of military forces in the world. The Portuguese Army also assimilated these technological advances and incorporated them in their activities, leading to a revolution in the modus operandi of the Armed Forces, designated by Revolution in Military Affairs. In the last few years, the Portuguese Army has developed two robots to perform surveillance and reconnaissance tasks, in several theaters of operations. The wireless communications with these robots need an antenna that should be robust, small sized, and which allows to vary the main lobe’s direction and width. Thus, an antenna designated by Electronically Steerable Parasitic Array Radiator (ESPAR) was dimensioned and simulated through the technique of genetic algorithms, which project is the main objective of this Master's Thesis. This antenna will allow the operator to have a directional antenna, enabling him to choose the direction in which the emission has a maximum gain. Varying the antenna’s mutual impedances changes the relation between the excitation currents, which in turn vary the direction and bandwidth of the main lobe, allowing to obtain different radiation patterns. The antenna was simulated and dimensioned in 4NEC2X program, to operate in the 2.4GHz band. After that, a matching circuit and a ground plane that optimized the antenna characteristics were designed. The ESPAR antenna, by its final characteristics, it complies with the necessary requisites to achieve communication with the robots, in the Portuguese Army theaters of operations

Proceedings of the Mobile Satellite Conference

A satellite-based mobile communications system provides voice and data communications to mobile users over a vast geographic area. The technical and service characteristics of mobile satellite systems (MSSs) are presented and form an in-depth view of the current MSS status at the system and subsystem levels. Major emphasis is placed on developments, current and future, in the following critical MSS technology areas: vehicle antennas, networking, modulation and coding, speech compression, channel characterization, space segment technology and MSS experiments. Also, the mobile satellite communications needs of government agencies are addressed, as is the MSS potential to fulfill them

High Frequency Receiver Front-End Module for Active Antenna Applications

This research is based on the analysis and development of an integrated receiver front-end module for high gain active antenna systems at the K-band (20GHz). In the design of conventional satellite receivers (such as reflector antennas), the system is usually specified by the gain/directivity, gain-to-temperature ratio (G/T) and radiation pattern requirements. The challenge in high gain active antenna systems development, in addition to beam-forming/beam-steering requirements, is to develop transmit/receive modules which will meet the power, noise and radiation pattern requirements of the conventional antenna. In order to guarantee an optimal design, it is important to be able to translate the specifications from the system level to the transistor level. The focus is on the development of a single-channel CMOS-based integrated receiver module. The G/T requirement is analysed to derive the noise figure and gain specifications for the low noise amplifier(LNA). An LNA design in 65nm CMOS is demonstrated to achieve a 2.6dB noise figure and uses only 7mW of DC power. The digital phased shifter specifications are studied. The generation of "quantization lobes" is analysed and used to estimate the number of bits based on side-lobe level requirements. The design of a 5-bit digital phase shifter based on quadrature signal modulation and a unique digital control logic is presented and tested at 20GHz. The phase shifter is shown to achieve 10dB input and output return loss between 16-21GHz. The effect of pattern tapering on the side-lobe level is investigated and used to specify the minimum dynamic range for a variable gain amplifier (VGA). A VGA design is demonstrated to meet this dynamic range with low phase-frequency variation. A schematic level design of the proposed single-channel array is studied featuring a hybrid coupler and switch for polarisation requirements, as well as a low-voltage bandgap reference circuit. Simulations results verify that the receiver can be used to generate two hands of polarisation (right and left) with <1.1dB axial ratio

The Third International Symposium on Space Terahertz Technology: Symposium proceedings

Papers from the symposium are presented that are relevant to the generation, detection, and use of the terahertz spectral region for space astronomy and remote sensing of the Earth's upper atmosphere. The program included thirteen sessions covering a wide variety of topics including solid-state oscillators, power-combining techniques, mixers, harmonic multipliers, antennas and antenna arrays, submillimeter receivers, and measurement techniques

Cooperative Radio Communications for Green Smart Environments

The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: • Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environments• Measurements, characterization, and modelling of radio channels beyond 4G networks• Key issues in Vehicle (V2X) communication• Wireless Body Area Networks, including specific Radio Channel Models for WBANs• Energy efficiency and resource management enhancements in Radio Access Networks• Definitions and models for the virtualised and cloud RAN architectures• Advances on feasible indoor localization and tracking techniques• Recent findings and innovations in antenna systems for communications• Physical Layer Network Coding for next generation wireless systems• Methods and techniques for MIMO Over the Air (OTA) testin

Cooperative Radio Communications for Green Smart Environments

The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: • Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environments• Measurements, characterization, and modelling of radio channels beyond 4G networks• Key issues in Vehicle (V2X) communication• Wireless Body Area Networks, including specific Radio Channel Models for WBANs• Energy efficiency and resource management enhancements in Radio Access Networks• Definitions and models for the virtualised and cloud RAN architectures• Advances on feasible indoor localization and tracking techniques• Recent findings and innovations in antenna systems for communications• Physical Layer Network Coding for next generation wireless systems• Methods and techniques for MIMO Over the Air (OTA) testin