Antennas and Wave Propagation :Electromagnetic Theory by By: Harish, A.R.; Sachidananda, M.

Antennas and Wave Propagation

Content and Structure of the Book

This book contains eight chapters which provide a comprehensive treatment of antennas and wave propagation.

Chapter 1 is essentially a review of basic electromagnetic theory. It also introduces the vector potential approach to the solution of the wave equation and the concept of the Hertzian dipole.

In Chapter 2, students are introduced to the terminology used for describing the radiation and input characteristics of antennas. The terms used for characterizing an antenna as a receiver are also clearly explained. The calculation of free space communication link budget is illustrated with examples.

The development of antenna theory starts from a study of the radiation from an infinitesimal current element. 

In Chapter 3, the field computation is extended to antennas carrying linear current distributions, e.g., short dipole, half-wave dipole, monopole, and loop antennas. Detailed procedures for the computation of the performance parameters of these antennas are also given.

A class of antennas which can be looked at as radiation from an aperture is treated in Chapter 4. Various forms of the field equivalence principle and its applications in the computation of the radiation fields of an aperture are explained. Several aperture type antennas, such as a slot, an open-ended wave guide, horn, reflector, etc., are also discussed.

Chapter 5 is devoted to the study of antenna arrays. It starts with the pattern multiplication principle and goes on to explain various pattern properties using a two-element array as an example. Use of polynomial representation of the array factor of a uniformly-spaced linear array and its pole-zero representation on a circle diagram is explained. The chapter ends with a discussion on the design of binomial and Chebyshev patterns.

A large number of specially designed antennas exist for specific usage requirements. 

Chapter 6 details a select set of such antennas under the title Special Antennas. These antennas cover a wide range of applications in various frequency bands. Some of the antennas discussed are monopole, V antenna, Yagi–Uda array, turnstile antenna, helix, spiral, microstrip patch, etc. The radiation pattern properties and some simple design procedures are explained.

Chapter 7 is focused on the techniques used to measure antenna parameters. Indoor and outdoor measurement ranges which provide free-space-like conditions for the antenna are explained. Schematic block diagrams of the measurement instrumentation are presented. Procedures for the measurement of the gain, directivity, radiation pattern, etc. are also discussed.

Finally, Chapter 8 deals with the issues related to the propagation ofradio waves. In this chapter, we study the interaction of the media and the discontinuities with electromagnetic waves. The effect of the earth and the troposphere on the propagation of electromagnetic waves is considered in detail. This is followed by an exposition of the nature of the ionosphere and its effect on sky wave propagation.

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