*Antenna Theory: Analysis and Design, Third Edition*by Constantine A. Balanis. This book is a must have for engineers who want to learn the theory behind antenna design. This textbook assumes that the reader has a fundamental theory of electromagnetics and Maxwell's Equations. The book is aimed at graduate engineering students. However, senior level undergraduate students would be able to understand the material provided they've already taken courses in electromagnetics. The front cover of the book is shown below.

Antenna Theory: Analysis and Design by Constantine A. Balanis |

Balanis is well known in the antenna theory, design, and engineering fields. Although his textbook does not cover every aspect of antenna design, he goes into great detail on the theoretical concepts one needs to understand in order to design antennas. For example, Balanis covers the following topics in good details in the second chapter of his text:

- Definition of of reactive near-field, radiating near-field, and far-field (Fraunhofer) regions
- Radiation power density and intensity derivations
- General derivation of directivity for antennas with arbitrary sources
- Derivations of equations defining antenna efficiency and gain
- Definitions of linear, circular, and elliptical polarizations
- Derivation of the Friis transmission and radar range equations

As I mentioned above,

__Antenna Theory: Analysis and Design__covers many aspects of antenna theory. As such, Balanis has an entire chapter devoted to derivation of vector potentials and how they are used to derive the radiated fields**E**&**H**. For example, Balanis explains that it is generally easier to derive the radiated fields based on electric current density**J**and/or magnetic current density**M**by deriving the associated vector potentials and taking their derivatives. The more direct path of integrating**J**or**M**to obtain the resulting electromagnetic fields is much harder in comparison because the integrals do not always exist or are hard to solve based on the problem. After deriving the vector potentials, Balanis derives general solutions for the inhomogeneous vector potential wave equation, and he derives basic far-field radiation field equations based on the electric and magnetic vector potentials. Lastly, Balanis derives the equations that explain antenna reciprocity. His solutions incorporate circuit theory by modeling the antennas as sources with equivalent voltages and currents.
In Chapter 4, Balanis derives the equations that define the radiation patterns for linear wire antennas. This includes the electromagnetic fields for several types of dipole antennas such as the infinitesimal dipole, small dipole, and half-wavelength dipole. Balanis also gives detailed derivations for the far-field (Fraunhofer) and the radiating near-field regions. Next, Balanis defines the current distribution on dipole antennas and derives their radiation resistance as a function of length. This chapter is very important for understanding antenna theory, as the dipole antenna is considered to be a very basic antenna element, and they are often used in wireless communication systems.

### Tip # 1: If your goal is to get a basic understanding of dipole antenna theory, read and thoroughly understand the materials that Balanis covers in the first four chapters.

### Tip # 2: Read Chapter 5 if you want to understand how loop antennas operate as well.

Next, Chapter 5 derives the equations for loop antennas. The loop antenna is considered a dual to the dipole antenna, as both antennas have similar radiation patterns. Whereas the dipole antenna has an electric current density

**J**as its radiating source, the loop antenna has a magnetic current density**M**as its radiating source. I strongly suggest that you read this chapter if your position or research involves loop antennas.In addition, the following chapters in this textbook are dedicated to specific subfields within antenna theory. The subjects include but are not limited to

- Antenna arrays
- Antenna synthesis
- Integral equations and the method of moments (MOM)
- Broadband dipoles and matching techniques
- Broadband antennas
- Horn antennas
- Microstrip (including patch) antennas

Finally, the last chapter in Balanis' textbook is one devoted solely to antenna measurements. Balanis explains several methods of measuring an antenna's radiation patterns such as reflection ranges, free-space-ranges, and compact ranges. He also explains how a test range can be made more compact by making near-field measurements, and he derives methods for extracting far-field data from near-field measurements. Furthermore, Balanis describes the equipment necessary for measuring antenna fields as well as radar cross sections (RCS) of various targets.

In conclusion,

__Antenna Theory: Analysis and Design (Third Edition)__is an excellent textbook for learning antenna theory. It is certainly not the only textbook one should read on antennas. However, this book is certainly a great start for understanding how antennas operate.
Sincerely,

Jonathan Becker

ECE PhD Candidate

Carnegie Mellon University