A Review: Substrate Integrated Waveguide Antennas and Arrays

This study aims to provide an overview and deployment of Substrate-Integrated Waveguide (SIW) based antenna and arrays, with different configurations, feeding mechanisms, and performances. Their performance improvement methods, including bandwidth enhancement, size reduction, and gain improvement are also discussed based on available literature. SIW technology, which acts as a bridge between planar and non-planar technology, is a very favorable candidate for the development of components operating at microwave and millimeter wave band. Due to this, SIW antennas and array take the advantages of both classical metallic waveguide, which includes high gain, high power capacity, low cross polarization, and high selectivity, and that of planar antennas which comprises low profile, light weight, low fabrication cost, conformability to planar or bent surfaces, and easy integration with planar circuits

A Period-Reconfigurable Leaky-Wave Antenna with Fixed-Frequency and Wide-Angle Beam Scanning

© 1963-2012 IEEE. A novel fixed-frequency beam-scanning leaky-wave antenna (LWA) based on a period-reconfigurable structure is presented. Operating at 5 GHz, the antenna consists of a slotted substrate integrated waveguide and 54 electrically small patches. Each patch element is etched with two dumbbell-shaped slots, and its operating state can be flexibly controlled by the biasing of the p-i-n diode on a parasitic strip. An ideal array model employing isotropic point sources is used for the analysis on the scanning mechanism, based on which a new method for suppressing the higher order space harmonics is developed. Using this method, the monoharmonic radiation range can be dramatically extended, and a wide-angle beam scanning can be achieved by manipulating the period length of the LWA. An FPGA controlling platform is designed for the electronic control of the antenna. The measured results validate that the proposed antenna achieves good performance of wide-angle scanning (125°) with a peak gain of 11.8 dBi at a fixed frequency

Circuit Model for Microstrip Array Antenna with Defected Ground Structures for Mutual Coupling Reduction and Beamforming Applications

A microstrip array antenna (MAA) structure incorporated with an orthogonal I-shaped defected ground structure (OI-DGS) was proposed and investigated and its equivalent circuit was created. Reflection losses were simulated and verified with the proposed circuit model using CST Commercial and AWR Microwave Office software. The optimized S11 parameter of the model was obtained by tuning the dimensions of the microstrip patch elements in the MAA and the lengths and widths of the slots of defected ground structure (DGS). The proposed equivalent circuit is expected to be useful as a model for the DGS design and to study its behavior. Finally, two prototypes of MAA, without and with OI-DGS, were fabricated by the milling technology and tested. The simulated results showed that -5.53 dB mutual coupling reduction and the measured around -3 dB. The simulated results demonstrate that main beam shifted 43° while the measured main beam shifted 36°

Defected Ground Structure: Fundamentals, Analysis, and Applications in Modern Wireless Trends

Slots or defects integrated on the ground plane of microwave planar circuits are referred to as Defected Ground Structure. DGS is adopted as an emerging technique for improving the various parameters of microwave circuits, that is, narrow bandwidth, cross-polarization, low gain, and so forth. This paper presents an introduction and evolution of DGS and how DGS is different from former technologies: PBG and EBG. A basic concept behind the DGS technology and several theoretical techniques for analysing the Defected Ground Structure are discussed. Several applications of DGS in the field of filters, planar waveguides, amplifiers, and antennas are presented

An improved 2×2 array antenna using both-sided microwave integrated circuit technology for circular polarization

A circularly polarized microstrip patch array antenna using both-sided microwave integrated circuit (MIC) technology with a triple feed network has been proposed in this article. The antenna elements, feed structure and both-sided MIC technology are used and arranged in such a way to obtain circular polarization alongside high gain without using an external matching circuit. The 50 Ω microstrip line is used to energize the antenna where the antenna’s total feed network is made up of both series and parallel combinations of microstrip and slot line. The antenna was realized using Teflon glass fiber substrate (εr)=2.15 with a thickness of 0.8 mm. The antenna has some splendid parameters including S11 of less than -35 dB, a gain of 12 dBi with an omnidirectional pattern and an axial ratio of 0.7 dB at the operating frequency. The antenna possesses a bandwidth of 430 MHz (4.22%) after operating at X-band in the frequency spectrum. The antenna’s simulated parameters were investigated with the help of advanced design system (ADS) simulation software in microwave momentum mode

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

The Complementary Strip-Slot: Analysis and Antenna Applications

Aunque el diseño de la antena en un sistema de comunicaciones pueda parecer un problema clásico, los servicios que han aparecido recientemente requieren nuevas funcionalidades, mayores anchos de banda, mejor eficiencia y directividad, así como bajo coste en la fabricación. Las antenas planares han sido unas de las más usadas y estudiadas en las últimas décadas y unas de las mejores candidatas para los nuevos servicios de telecomunicación. Sus ventajas son claras: poco peso, bajo coste y perfil, compatibilidad con la circuitería integrada, pequeño tamaño y reducido coste de fabricación. Sin embargo, su éxito se ha visto limitado por el escaso ancho de banda que presentan. Debido a la naturaleza resonante de la ranura y el parche alimentados por microstrip, sus anchos de banda en impedancia son insuficientes para la mayoría de los servicios de comunicaciones actuales. La mejora de este parámetro ha sido objeto de numerosas investigaciones; sin embargo, este problema sigue sin estar resuelto definitivamente y constituye una línea importante de investigación en antenas planares. Otra limitación de las antenas microstrip es la baja eficiencia de radiación comparada con otras antenas, que se supera combinando varios elementos para formar arrays. Una posibilidad para excitar el array es la alimentación en serie, que tiene las ventajas de simplicidad, menor espacio sobre el sustrato, pérdidas de atenuación más bajas y menor radiación espúrea, comparada con la alimentación corporativa. En esta tesis doctoral se ha propuesto un nuevo elemento radiante, el denominado strip-slot complementario, cuya principal característica es la eliminación de la naturaleza resonante de la antena de ranura excitada a través de línea microstrip por medio de introducir una strip (tira conductora) superpuesta a la ranura y en la cara de la microstrip. Con esta sencilla modificación, se crea una sección acoplada que puede diseñarse para presentar un comportamiento paso-todo. Las principales ventajas de la estructura son su simplicidad, que posee un único sustrato y que no necesita vías, lo que se traduce en bajo coste. Además, su alimentación en serie la hace muy apropiada para construir arrays de onda progresiva. Se ha analizado el comportamiento electromagnético de esta estructura y se ha obtenido un circuito equivalente basado en red en celosía que no sólo explica sus propiedades, sino que permite, además, establecer una eficaz metodología de diseño. Cabe destacar el trabajo relacionado con las redes en celosía. Se ha extraído una propiedad relevante sobre la independencia de las potencias disipadas en esta topología de circuito, que ha permitido explicar por qué la strip no altera las propiedades radiantes de la ranura. Además, esta red circuital se ha propuesto de una forma más general para el modelado de discontinuidades y componentes de LT simétricos, con la ventaja de garantizar la realizabilidad física de sus componentes, a diferencia de las ampliamente usadas redes en T o en π. Una vez caracterizado el elemento radiante propuesto, se ha ilustrado su potencial con una serie de novedosos diseños de arrays de antenas que se benefician de su elevado ancho de banda para proporcionar nuevas funcionalidades. En primer lugar, se estudia el concepto de array más inmediato, que consiste en cargar la línea microstrip con varios elementos strip-slot idénticos. Con un sencillo prototipo, se demuestra la capacidad de escaneo en frecuencia de atrás hacia delante del array (incluyendo broadside) en dos bandas distintas. Además, se diseña y construye un prototipo más sofisticado, que incluye desfasadores entre los elementos, con el objetivo de controlar el ángulo de apuntamiento de forma electrónica, sobre una banda ancha de frecuencias, sin necesidad de modificar la geometría del elemento radiante gracias a su gran ancho de banda. Esta antena representa una contribución importante a las propuestas del estado del arte. A continuación, se estudia el concepto de un array log-periódico basado en el elemento strip-slot, a través de un diseño y su correspondiente prototipo. Para ello, es necesario adaptar la metodología de diseño, concebida para elementos resonantes, y trasladarla al caso de elementos de banda ancha. La reconsideración de dicha metodología puede ser una aportación significativa, puesto que indica la posibilidad de reducción de tamaño (o anchos de banda mayores) cuando se utilizan elementos no-resonantes. Finalmente, se aborda el diseño de un array que implementa la técnica de rotación secuencial con los elementos strip-slot para proporcionar agilidad en polarización. Además, como aplicación del concepto, se incluye la propuesta de una novedosa antena con capacidad diplexora para la recepción simultánea de dos bandas de navegación por satélite, que no requiere de elementos pasivos o activos adicionales. Puesto que se ha presentado una nueva clase de antenas, basada en la estructura radiante de banda ancha strip-slot, y se han diseñado diferentes topologías con características atractivas que contribuyen al estado del arte y son de aplicación en diversos campos, se puede afirmar que esta tesis ofrece una perspectiva nueva para las antenas planares, basadas en elementos no-resonantes

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

A Comprehensive Survey on “Various Decoupling Mechanisms With Focus on Metamaterial and Metasurface Principles Applicable to SAR and MIMO Antenna Systems”

Nowadays synthetic aperture radar (SAR) and multiple-input-multiple-output (MIMO) antenna systems with the capability to radiate waves in more than one pattern and polarization are playing a key role in modern telecommunication and radar systems. This is possible with the use of antenna arrays as they offer advantages of high gain and beamforming capability, which can be utilized for controlling radiation pattern for electromagnetic (EM) interference immunity in wireless systems. However, with the growing demand for compact array antennas, the physical footprint of the arrays needs to be smaller and the consequent of this is severe degradation in the performance of the array resulting from strong mutual-coupling and crosstalk effects between adjacent radiating elements. This review presents a detailed systematic and theoretical study of various mutual-coupling suppression (decoupling) techniques with a strong focus on metamaterial (MTM) and metasurface (MTS) approaches. While the performance of systems employing antenna arrays can be enhanced by calibrating out the interferences digitally, however it is more efficient to apply decoupling techniques at the antenna itself. Previously various simple and cost-effective approaches have been demonstrated to effectively suppress unwanted mutual-coupling in arrays. Such techniques include the use of defected ground structure (DGS), parasitic or slot element, dielectric resonator antenna (DRA), complementary split-ring resonators (CSRR), decoupling networks, P.I.N or varactor diodes, electromagnetic bandgap (EBG) structures, etc. In this review, it is shown that the mutual-coupling reduction methods inspired By MTM and MTS concepts can provide a higher level of isolation between neighbouring radiating elements using easily realizable and cost-effective decoupling configurations that have negligible consequence on the array’s characteristics such as bandwidth, gain and radiation efficiency, and physical footprint