Evolution of Satellite Communication Antennas on Mobile Ground Terminals

Getting connected whenever and wherever you travel is not kind of luxury any more. Satellite communication researchers are making it a reality to bring you data, video, and voice services when you are away from home, out of office, or on a long journey. Satellite communication antenna mounted on mobile ground terminals is an essential prerequisite of successful connectivity. In this paper, we review the evolution of this kind of antenna in its historical context and outline the major research achievements on ground mobile terminals. Many striking demonstrations and prototypes are revisited to understand the emerging technologies and assess their potential towards practical implementations. The future trends and challenges are also discussed

Circularly polarized and reconfigurable frequency selective surface based transmit array antenna for x-band applications

Transmitarray (TA) antennas have attracted much attention in recent years due to their number of applications. These include the 5G/6G mobile networks and satellite communication systems for the microwave frequency range. The various satellite applications require high-gain antennas with polarization agility. Also, the state-ofthe- art smart communication systems require reconfigurable antennas allowing the frequency and beam switching according to the application requirements. In this research, three different TA antennas have been studied and designed for X-band applications which are high gain and wideband TA antenna, circularly polarized TA antenna, frequency and beam reconfigurable TA antenna. For the first design, two Frequency-Selective Surface (FSS) unit cells which include Double Square Ring with Center Patch (DSR-CP) and Split Ring Resonator (SRR), have been applied to increase the antenna gain and bandwidth. The optimized unit cell structure shows that a fourlayer configuration could provide maximum phase range with low insertion losses. The complete DSR-CP TA consisting of 121 elements has produced an impedance bandwidth of 33.3% with a peak gain value of 20.4 dBi and 1-dB gain for bandwidth of 10%. SRR-based TA achieved the impedance bandwidth of 35% with a peak gain value of 21.9 dBi and 11.6% 1-dB gain bandwidth. A circularly polarized TA using a Meander Line Polarizer (MLP) superstrate has been studied and presented. The MLP unit cell was simulated and optimized at 12 GHz, having 900 phase difference between the two orthogonal E-field components, Ex and Ey. The final prototype measurement results show that a low axial ratio of 1.89 and 20.17 dBi gain at 11.2 GHz has been obtained. Finally, the last part of the research focused on the frequency and beam reconfigurable TA antenna. A U-shape superstrate layer has been added to introduce frequency selectivity in front of the horn antenna that acts as a bandpass filter. Then, by varying the strip length of the U-shape unit cell, the antenna frequency can be reconfigured from 8.5 GHz to 11.2 GHz. On the other hand, a new active TA unit cell equipped with four switchable strips using Positive Intrinsic Negative (PIN) diodes has been employed to achieve beam reconfigurable TA antenna. Thus, the antenna beam can be tilted by controlling the PIN diodes ON and OFF switching states. Results show that a full-beam switching range of 43.20 has been obtained. In conclusion, this research has successfully presented three new TA antenna designs, which are highly potential for the X-band applications

IEEE Access Special Section: Antenna and Propagation for 5G and Beyond

5G is not just the next evolution of 4G technology; it is a paradigm shift. “5G and beyond” will enable bandwidth in excess of 100s of Mb/s with a latency of less than 1 ms, in addition to providing connectivity to billions of devices. The verticals of 5G and beyond are not limited to smart transportation, industrial IoT, eHealth, smart cities, and entertainment services, transforming the way humanity lives, works, and engages with its environment

Advanced Radio Frequency Antennas for Modern Communication and Medical Systems

The main objective of this book is to present novel radio frequency (RF) antennas for 5G, IOT, and medical applications. The book is divided into four sections that present the main topics of radio frequency antennas. The rapid growth in development of cellular wireless communication systems over the last twenty years has resulted in most of world population owning smartphones, smart watches, I-pads, and other RF communication devices. Efficient compact wideband antennas are crucial in RF communication devices. This book presents information on planar antennas, cavity antennas, Vivaldi antennas, phased arrays, MIMO antennas, beamforming phased array reconfigurable Pabry-Perot cavity antennas, and time modulated linear array

1-D broadside-radiating leaky-wave antenna based on a numerically synthesized impedance surface

A newly-developed deterministic numerical technique for the automated design of metasurface antennas is applied here for the first time to the design of a 1-D printed Leaky-Wave Antenna (LWA) for broadside radiation. The surface impedance synthesis process does not require any a priori knowledge on the impedance pattern, and starts from a mask constraint on the desired far-field and practical bounds on the unit cell impedance values. The designed reactance surface for broadside radiation exhibits a non conventional patterning; this highlights the merit of using an automated design process for a design well known to be challenging for analytical methods. The antenna is physically implemented with an array of metal strips with varying gap widths and simulation results show very good agreement with the predicted performance

New solutions for directive antennas and components for millimeter wave-band applications

Mención Internacional en el título de doctorEn las últimas décadas se ha producido un avance tecnológico exponencial en el área de las telecomunicaciones. Cada pocos años surgen sistemas de comunicaciones de nueva generación, siendo el 5G el que, hoy en día, se va implementando y ofreciendo progresivamente a los usuarios de todo el mundo. Los sistemas de comunicaciones 5G permiten tasas de datos mucho más altas, una velocidad ultrarrápida y un mayor ancho de banda que el 4G no soportaba debido a las bandas excesivamente utilizadas por debajo de los 6 GHz. Sin embargo, este aumento de la frecuencia introduce retos que no existen en frecuencias inferiores, como la absorción ambiental. Además, los obstáculos físicos que se interponen en el trayecto entre el emisor y el receptor también son un problema a estas frecuencias y las pérdidas inherentes a la propagación en el espacio libre son muy elevadas. El objetivo de esta tesis ha sido desarrollar e introducir nuevos e innovadores diseños de antenas que puedan ser utilizados en las bandas de frecuencia de las comunicaciones 5G y superiores así como en otras aplicaciones de ondas milimétricas. Los diseños que se presentan tienen como principal objetivo conseguir una alta directividad, manteniendo bajas pérdidas. Estos diseños se pueden agrupar en dos categorías principales: antenas Fabry-Pérot, y antenas gap waveguide. En la primera parte de esta tesis se han desarrollado tres diseños de antena Fabry-Pérot, incluyendo una metodología innovadora para el diseño de una metasuperficie que permite un funcionamiento en doble banda con control de directividad y que también puede ser utilizada también para implementar arrays de antenas en bandas de ondas milimétricas. Además, se muestra que este concepto de antenas Fabry-Pérot, implementado en un rango de frecuencias mucho más bajas, puede utilizarse también en aplicaciones de sistemas radar. En la segunda parte, se han desarrollado e implementado diseños innovadores de antenas y arrays usando la tecnología gap waveguide en particular su versión groove. En ellos, se han diseñado novedosas redes de alimentación y sistemas de corrección de fase que proporcionan bajas pérdidas y alta eficiencia.Programa de Doctorado en Multimedia y Comunicaciones por la Universidad Carlos III de Madrid y la Universidad Rey Juan CarlosPresidente: José Luis Masa Campos.- Secretario: Óscar Quevedo Teruel.- Vocal: Guido Valeri

Beam scanning by liquid-crystal biasing in a modified SIW structure

A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium

Phase Shaping In The Infrared By Planar Quasi-periodic Surfaces Comprised Of Sub-wavelength Elements

Reflectarrays are passive quasi-periodic sub-wavelength antenna arrays designed for discrete reflected phase manipulation at each individual antenna element making up the array. By spatially varying the phase response of the antenna array, reflectarrays allow a planar surface to impress a non-planar phasefront upon re-radiation. Such devices have become commonplace at radio frequencies. In this dissertation, they are demonstrated in the infrared for the first time--at frequencies as high as 194 THz. Relevant aspects of computational electromagnetic modeling are explored, to yield design procedures optimized for these high frequencies. Modeling is also utilized to demonstrate the phase response of a generalized metallic patch resonator in terms of its dependence on element dimensions, surrounding materials, angle of incidence, and frequency. The impact of realistic dispersion of the real and imaginary parts of the metallic permittivity on the magnitude and bandwidth of the resonance behavior is thoroughly investigated. Several single-phase reflectarrays are fabricated and measurement techniques are developed for evaluating these surfaces. In all of these cases, there is excellent agreement between the computational model results and the measured device characteristics. With accurate modeling and measurement, it is possible to proceed to explore some specific device architectures appropriate for focusing reflectarrays, including binary-phase and phase-incremental approaches. Image quality aspects of these focusing reflectarrays are considered from geometrical and chromatic-aberration perspectives. The dissertation concludes by briefly considering two additional analogous devices--the transmitarray for tailoring transmissive phase response, and the emitarray for angular control of thermally emitted radiation

Antennas and Propagation

This Special Issue gathers topics of utmost interest in the field of antennas and propagation, such as: new directions and challenges in antenna design and propagation; innovative antenna technologies for space applications; metamaterial, metasurface and other periodic structures; antennas for 5G; electromagnetic field measurements and remote sensing applications