annotated biblography on antenna or microwave

annotated biblography on antenna or microwave

Antenna and Microwave Technologies: A Comprehensive Review

1. Introduction

The subject of this book is concerned with the teaching of electrical technology to mechanical students with a view to helping them to acquire the principles and the knowledge of electrical engineering which will be needed in their future professional work, and also gives an introduction to the application of electrical power to some special branches of mechanical engineering. In this connection, it often happens that a student who has passed his higher School Certificate with an excellent grade in Physics and perhaps gained a distinction in the appropriate Further Mathematics paper, wishes to become a mechanical engineer. If such a student takes a normal mechanical engineering course at University, the first chance for him to study electrical technology will be by selecting the subject as an option in the third or fourth year of his course. This text would not be suitable for him because it would not contain sufficient instructional material and would be too much concerned with other readers. On the other hand a student who leaves school before obtaining the usual qualifications for entry to University, sometimes finds himself serving an apprenticeship or technician apprenticeship, in the course of which he must attend a College of Further Education on a day-release or full-time basis, and there take the appropriate City and Guilds Technicians course. Often such a student is required to begin the subject of electrical technology for the first time at College, in a class which is considerably below the Higher National or Ordinary National Certificate standard, but during his period at College and during his subsequent professional work, he may make very rapid progress. Whether the more advanced student should start his electrical technology with Book 1 will depend upon his existing knowledge of the basic laws of physics and electrical engineering. If he knows these well, then Book 1 will be largely a revision of known facts and principles for him, but it may help him to see how these can often begin his electrical technology with Book 1 will depend upon his existing knowledge of the basic laws of physics and electrical engineering. If he knows these well, then Book 1 will be largely a revision of known facts and principles for him, but it may help him to see how these can often be applied to simple electrical circuits. For the student who possesses little mathematical knowledge, it is important that he should try to understand the statement of a law or theory before reading its mathematical proof. Such students would do well to resort to the suggested methods of individual study, either alone or in small groups, with the use of explanatory diagrams and discussions.

2. Fundamentals of Antenna Design

In most cases, an antenna is designed to function with a particular transmitter or receiver, and these should be considered as part of the entire antenna system. The objective of the system is to transmit or receive signals to or from a particular load. The antenna is simply the interface structure between the source and free space or the receiver and free space and can be characterized as a transition of electromagnetic waves between a guided system and a radiated system.

Despite the complexity of modern antennas or the difficulties involved in implementing them, the fundamental principle of the antenna remains the same: efficient transfer of electrical currents into radio waves and vice versa. Understanding this is the key to understanding the design and function of all types of antennas.

Fundamentally, antennas are simple devices. An electrical current is applied to the antenna’s terminals, which excites the antenna and causes the production of radio waves. At the receiving end, the reverse process occurs. The electromagnetic waves impinging upon the antenna cause an electrical current to be induced, which can then be used by the receiving system. This is a simplistic view, however, and modern antennas are rarely so simple due to various practical and economic constraints.

Antennas are a device for transmitting and/or receiving electromagnetic waves. Also known as aerials, antennas are used in various applications to send and receive radio frequency signals. Anything from garage door openers and cell phones to satellite dishes and radio stations all rely on some type of antenna to function. In recent years, antenna design and technology has rapidly advanced; effective antenna design is crucial to a large and ever-increasing number of systems and devices.

3. Microwave Technologies and Applications

Microwaves are the waves with a wavelength ranging from as long as one meter to as short as one millimeter, or equivalently, with a frequency between 300 MHz (0.3 GHz) and 300 GHz. They are differentiated from radio waves, which have longer wavelengths. Microwaves are used in many different applications. Some of these application areas, such as telecommunications, have been important for several decades. Many other areas are only now emerging as enabling new technologies. In each of these areas, the choice of microwave frequency over other frequencies (e.g. lower frequencies or light) is usually due to some combination of (a) available technology, (b) propagation environment and (c) regulatory constraints. The workhorse for telecommunication over long distances is the undersea optical cable, which provides enormous bandwidth at very low cost per bit. However, for shorter point-to-point links, microwaves are still very important. In developed nations, one sees a profusion of communications masts at frequencies around 6 GHz, and this is also a very active area for development in the third world. Wireless local area networks for internet have been a notable success story over the past 5 years, with IEEE 802.11 at 2.4 GHz and 5 GHz being the chief technology. WiMax is an attempt to bring similar wireless networking to third world, and there is as yet no consensus whether it is best done using microwave or lower frequencies.

4. Recent Advances in Antenna and Microwave Research

In the past two decades, we have seen a virtual explosion of activity related to antenna theory and design. This has been largely due to increased demands for types of antennas capable of operating in new frequency bands (UHF and microwave) for new and existing systems, as well as the advent of new computer-based design techniques which have allowed for the systematic design of broadband antennas. Traditional antenna design was concerned with achieving, from a given antenna volume, an impedance bandwidth of perhaps 2-3% at a single design frequency. The device would be tested (usually in an anechoic chamber), and if it fell short of this requirement, sections would be cut and the antenna re-tested. This cut and try approach to antenna design was time-consuming and often not very successful. With the advent of modern computational methods, the situation has been reversed. Broadband antennas are designed by specifying a desired far-field radiation pattern (either qualitatively or quantitatively). This pattern requirement is usually imposed by system-level considerations. The radiating antenna surface is an inverse scattering problem (after removing the phase factor), and thus it is possible to calculate the surface current required to produce a near-arbitrary far-field pattern. This current may be realized with complex (vector) surface impedance or admittance. The latter can be approximately realized by a combination of series and parallel R-L-C circuits. In the case of wideband antenna design, it is most desirable to use lumped components. The modern approach to wideband antenna design has been largely one of applied electromagnetics, and in many cases, it involves new antenna concepts and topologies. Wideband antennas are an active area of research and will continue to be so for the immediate future.

5. Conclusion and Future Directions

Antenna and Microwave Technologies: A comprehensive review provides a strong foundation for understanding antenna technologies, in general, and microwave antennas in particular. The content of this book spans from the introductory concepts to the most current developments. Also, in this book, the necessary fundamental concepts related to the antenna theory and electromagnetic theory needed to understand the complex antenna are discussed in depth. The book contains exhaustive treatment of antenna designs using a wide range of transmission line and waveguide structures. The book explains details of antennas in radar systems and mobile communications. The book also provides current and potential users with an understanding of the theoretical limits of performance, as well as the practical advantages and obstacles in the development process. The wide readership that will benefit from this book includes practicing antenna and associated engineers needing a contemporary overview and an understanding of the potential trends for development of antennas and microwave systems, a useful reference tool for new researchers to understand the historical and current trends in the development of microwave antennas and a resource for educations at both undergraduate and postgraduate levels. This book provides useful information for mathematicians, electromagnetic enthusiasts, RF electrical engineering and physics persons in general who hitherto may have considered the study of antennas as too challenging due to the welter of complex expressions and diagrams. An instructor package including detailed solutions to all the problems in the book, further resources and to maintain currency, PPT slides will be available from the book website.