Design And Testing Of A Frequency Selective Surface Fss Based Wide Band Multiple Antenna System
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Design and Testing of a Frequency Selective Surface (FSS) Based Wide-band Multiple Antenna System
Abstract: Since the first radio link was built by Hertz in 1886, antennas have become a critical technology which allows people to stay connected and informed. Several advances have been made in the field of antenna theory and technology in the past hundred twenty years. Among them is the characterization of frequency selective surfaces (FSS), which are periodic arrays of passive elements or slots that act as a band stop or a band pass filters respectively to propagating electromagnetic waves. The purpose of this project was to construct an antenna which is transmissive outside of the band of operation. For example, the antenna designed in this project operates in a band of 1-2 GHz. The goal of this project is to be able to place an antenna operating at 4-8 GHz behind this antenna and have it be able to "look though" the first antenna as if it wasn't there. This will allow the user to stack antennas one behind the other and thus increase the density of antennas in a given area. This is advantageous in applications where the available real estate upon which to place antennas is limited, such as on ships and submarines. This antenna has two main components - an array of radiating elements and a reflector. The radiating array will be transmissive at 4-8 GHz as long as it does not radiate energy at this frequency and does not significantly scatter energy. These constraints are easily met by creating an array of wire elements. Reflectors, on the other hand, are commonly composed of a solid metal plate, which will reflect energy at any frequency. However, this project uses an element FSS for a reflector. As a result this reflector will only reflect energy in the stop band. Sufficiently outside of this band, it will be transmissive. While an entire antenna was designed for sake of completeness, the focus of this project was the design and testing of the FSS reflector. There were two main components to this project. The first was to use computational codes to design the antenna. Specifically, the antenna was designed using a Method of Moments (MoM) code, which calculates gain patterns for finite antennas. These results were then compared to a periodic moment method code, which calculates the ideal result for an infinite structure. This design process was completed in several steps. First the FSS array was designed to be reflective in the L band (1-2 GHz) and transmissive outside of this band. Following this the radiating array was designed to realize sufficiently flat L band bandwidth. The FSS reflector and radiating array were then combined together and the gain and transmissivity were then calculated for the entire antenna. Finally a prototype of the FSS reflector was built and tested. Time constraints prevented the construction of the entire antenna. The results of these tests are in very good agreement with each other. MoM tests show the FSS is within 1 dB of perfect reflectivity over the entire L band range. The prototype was within 2 dB of perfect reflectivity over the same range. This deviation is explained by unavoidable human error in the construction of the FSS. The periodic moment method code is also computed similar results. The bandwidth wasn't quite as large in the PMM test, but this is expected and is explained by the fact that edge diffraction on finite structures increases the bandwidth. The transmissivity of this FSS is within 2 dB of perfect transmissivity in the C band (4-8 GHz.) Finally the gain of the radiating array has a 2 dB variation over L and, and the gain of the entire antenna has a 3 dB variation over L band.
Analysis and Design of Transmitarray Antennas
Author: Ahmed H. Abdelrahman
language: en
Publisher: Springer Nature
Release Date: 2022-06-01
In recent years, transmitarray antennas have attracted growing interest with many antenna researchers. Transmitarrays combines both optical and antenna array theory, leading to a low profile design with high gain, high radiation efficiency, and versatile radiation performance for many wireless communication systems. In this book, comprehensive analysis, new methodologies, and novel designs of transmitarray antennas are presented. Detailed analysis for the design of planar space-fed array antennas is presented. The basics of aperture field distribution and the analysis of the array elements are described. The radiation performances (directivity and gain) are discussed using array theory approach, and the impacts of element phase errors are demonstrated. The performance of transmitarray design using multilayer frequency selective surfaces (M-FSS) approach is carefully studied, and the transmission phase limit which are generally independent from the selection of a specific element shape is revealed. The maximum transmission phase range is determined based on the number of layers, substrate permittivity, and the separations between layers. In order to reduce the transmitarray design complexity and cost, three different methods have been investigated. As a result, one design is performed using quad-layer cross-slot elements with no dielectric material and another using triple-layer spiral dipole elements. Both designs were fabricated and tested at X-Band for deep space communications. Furthermore, the radiation pattern characteristics were studied under different feed polarization conditions and oblique angles of incident field from the feed. New design methodologies are proposed to improve the bandwidth of transmitarray antennas through the control of the transmission phase range of the elements. These design techniques are validated through the fabrication and testing of two quad-layer transmitarray antennas at Ku-band. A single-feed quad-beam transmitarray antenna with 50 degrees elevation separation between the beams is investigated, designed, fabricated, and tested at Ku-band. In summary, various challenges in the analysis and design of transmitarray antennas are addressed in this book. New methodologies to improve the bandwidth of transmitarray antennas have been demonstrated. Several prototypes have been fabricated and tested, demonstrating the desirable features and potential new applications of transmitarray antennas.
Handbook of Metamaterial-Derived Frequency Selective Surfaces
This volume provides a consolidated reference for the applications of frequency selective surfaces (FSS) technology in different sectors such as wireless communications, smart buildings, microwave and medical industries. It covers all aspects of metamaterial FSS technology starting from theoretical simulation, fabrication and measurement all the way to actual hardware implementation. Also included are in-depth discussions on the design methodologies of metamaterial FSS structures and their practical implementation in devices and components. It will be of interest to researchers and engineers working on developing metamaterial-FSS technology.