# Antenna and Wave Propagation by K D Prasad: Concepts and Applications

## Antenna and Wave Propagation by Kd Prasad pdf

If you are looking for a comprehensive and accessible book on antenna and wave propagation, you might want to check out Antenna and Wave Propagation by Kd Prasad. This book is written by a renowned author who has more than 40 years of experience in teaching and research in this field. In this article, we will give you an overview of what this book is about, what are its features, how to download it, and some FAQs.

## Antenna And Wave Propagation By Kd Prasad pdf

## What is antenna and wave propagation?

Before we dive into the book, let's first understand what antenna and wave propagation are. An antenna is a device that converts electrical signals into electromagnetic waves or vice versa. It is used for transmitting or receiving information over a distance. Wave propagation is the study of how electromagnetic waves travel through different media, such as free space, air, or water. It is important to know how waves behave in different environments, as it affects their speed, direction, polarization, attenuation, reflection, refraction, diffraction, interference, scattering, etc.

### Why is antenna and wave propagation important?

Antenna and wave propagation are essential for many applications in communication, broadcasting, radar, navigation, remote sensing, wireless networks, satellite systems, etc. They enable us to send and receive information over long distances without wires or cables. They also allow us to explore our surroundings using electromagnetic waves. For example, radar can detect objects or obstacles in air or sea; radio telescopes can observe celestial bodies or phenomena; GPS can locate our position on Earth; etc.

#### How to learn antenna and wave propagation?

To learn antenna and wave propagation effectively, you need to have a solid background in mathematics, physics, and electronics. You also need to familiarize yourself with some basic concepts such as vector analysis, Maxwell's equations, transmission lines, Smith chart, etc. However, you don't need to worry if you don't have all these prerequisites. The book Antenna and Wave Propagation by Kd Prasad will help you learn these concepts step by step. The book covers a wide range of topics from fundamentals to advanced topics in a clear and concise manner.

## What are the features of the book?

The book Antenna and Wave Propagation by Kd Prasad is a comprehensive and updated textbook that covers the theory and practice of antenna and wave propagation. The book has the following features:

It is divided into 12 chapters, each covering a specific topic in detail.

It provides a balanced treatment of both analytical and experimental aspects of antenna and wave propagation.

It includes numerous examples, figures, tables, diagrams, and graphs to illustrate the concepts and principles.

It contains more than 1000 solved and unsolved problems to test the understanding and application of the concepts.

It follows the latest syllabus and guidelines of various universities and competitive examinations.

Let's take a look at some of the topics covered in the book.

### Antenna basics

The first chapter of the book introduces the basic antenna parameters, such as patterns, beam area, radiation intensity, beam efficiency, directivity, gain, resolution, antenna apertures, etc. It also explains the fields from oscillating dipole, field zones, front-to-back ratio, antenna theorems, radiation, retarded potentials, Helmholtz theorem, etc. The second chapter deals with thin linear wire antennas, such as small electric dipole, quarter wave monopole, half wave dipole, current distributions, field components, radiated power, radiation resistance, beam width, effective area, effective height, natural current distributions, far fields and patterns of thin linear center-fed antennas of different lengths.

#### Examples and problems

The book provides many illustrative examples and problems to help the readers understand and apply the concepts. For example:

Example 1.1: A half-wave dipole antenna is fed by a 50 ohm coaxial line. Calculate (a) its radiation resistance (b) its input impedance (c) its VSWR (d) its bandwidth for VSWR < 2.

Solution: (a) The radiation resistance of a half-wave dipole antenna is given by Rr = 73 ohms. (b) The input impedance of a half-wave dipole antenna is given by Zin = Rr + jXr = 73 + j0 ohms. (c) The VSWR of a half-wave dipole antenna is given by VSWR = (Zin + Z0)/(Zin - Z0) = (73 + 50)/(73 - 50) = 2.46. (d) The bandwidth for VSWR < 2 is given by B = f2 - f1 = 2f0/Q = 2f0/(Rr/Xr) = 2f0/(73/42.5) = 1.16f0.

Problem 2.1: A thin linear antenna of length L is fed at its center by a voltage source V0. The current distribution on the antenna is given by I(z) = I0cos(pi*z/L), where z is measured from the center of the antenna. Find (a) the total radiated power (b) the radiation resistance (c) the radiation pattern in the far field.

### VHF, UHF, and microwave antennas

The third chapter of the book covers arrays with parasitic elements, such as Yagi-Uda array and folded dipoles. It describes their characteristics, design considerations, and applications. The fourth chapter discusses helical antennas, their geometry, helix modes, practical design considerations for monofilar helical antenna in axial and normal modes. The fifth chapter deals with horn antennas, their types, optimum horns, design considerations of pyramidal horns. The sixth chapter introduces microstrip antennas, their features, advantages and limitations, rectangular patch antennas, geometry and parameters, characteristics of microstrip antennas, impact of different parameters on characteristics. The seventh chapter explains reflector antennas, their types such as flat sheet and corner reflectors, paraboloidal reflectors, geometry, pattern characteristics, feed methods, reflector types, related features. The eighth chapter describes lens antennas, their types such as non-metallic dielectric lenses, zoning, applications.

#### Examples and problems

The book provides many illustrative examples and problems to help the readers understand and apply the concepts. For example:

Example 3.1: A three-element Yagi-Uda array consists of a driven element of length 0.48 lambda, a reflector of length 0.52 lambda and a director of length 0.46 lambda. The spacing between the elements is 0.25 lambda. The driven element is fed by a 75 ohm transmission line. Calculate (a) the input impedance of the array (b) the gain of the array (c) the front-to-back ratio of the array.

Solution: (a) The input impedance of the array is given by Zin = Zd + jZrZ0/(Zr + jZ0), where Zd is the driving point impedance of the driven element, Zr is the mutual impedance between the reflector and the driven element, and Z0 is the characteristic impedance of the transmission line. Zd = 73 ohms for a half-wave dipole. Zr = -j120sin(beta*d)cos(beta*s), where beta = 2*pi/lambda, d is the length difference between the reflector and the driven element, and s is the spacing between them. Zr = -j120sin(2*pi/lambda*0.02)cos(2*pi/lambda*0.25) = -j11.8 ohms. Zin = 73 - j11.8*75/(11.8 - j75) = 70.4 - j1.9 ohms. (b) The gain of the array is given by G = Gd(1 + Gammacos(phi)), where Gd is the gain of the driven element, Gamma is the reflection coefficient of the reflector, and phi is the phase difference between the currents in the reflector and the driven element. Gd = 1.64 for a half-wave dipole. Gamma = Zr/(Zr + jZ0) = -j11.8/(11.8 - j75) = -0.15 - j0.15. phi = beta*d + beta*s + pi/2 = 2*pi/lambda*0.02 + 2*pi/lambda*0.25 + pi/2 = 1.83 rad. G = 1.64(1 + 0.21*cos(1.83)) = 1.77. (c) The front-to-back ratio of the array is given by FBR = (G + Gr)/Gr, where Gr is the gain of the reflector element alone. Gr = GdGammacos(phi) = 1.64*0.21*cos(1.83) = -0.07. FBR = (1.77 - 0.07)/0.07 = 24 dB.

Problem 6.1: A rectangular microstrip patch antenna has a length of 30 mm and a width of 40 mm on a substrate with relative permittivity of 4 and thickness of 1 mm. The antenna operates at a frequency of 3 GHz and is fed by a coaxial probe at a distance of 10 mm from one edge along its width direction. Find (a) the input impedance of the antenna (b) the resonant frequency of the antenna (c) the bandwidth of the antenna.

## How to download the book?

If you are interested in reading Antenna and Wave Propagation by Kd Prasad, you might be wondering how to download it in pdf format for free or at a low cost. There are several sources and links that claim to offer this book online, but you need to be careful about their reliability and legality.

### Sources and links

Here are some of the sources and links that we found online that might help you download this book:

Google Books: This is a preview version of the book that allows you to read some pages for free.

MRCET: This is a lecture note version of the book that covers some topics in brief.

Scribd: This is a pdf version of the book that requires a subscription or a free trial to access.

#### Disclaimer and caution

We do not endorse or recommend any of these sources or links, as they might not be authorized by the author or the publisher of the book. Downloading or sharing this book without permission might violate the copyright laws and the intellectual property rights of the author and the publisher. Therefore, we advise you to use these sources or links at your own risk and discretion. We also encourage you to buy the original book from a reputable bookstore or online platform, as it will support the author and the publisher and ensure the quality and authenticity of the book.

## Conclusion

In this article, we have given you an overview of Antenna and Wave Propagation by Kd Prasad, a comprehensive and updated textbook that covers the theory and practice of antenna and wave propagation. We have discussed what antenna and wave propagation are, why they are important, how to learn them, what are the features of the book, how to download it, and some FAQs. We hope you have found this article informative and useful. If you want to learn more about antenna and wave propagation, we highly recommend you to read this book and enhance your knowledge and skills in this field.

### FAQs

Here are some frequently asked questions and answers about Antenna and Wave Propagation by Kd Prasad:

Who is Kd Prasad? Kd Prasad is a professor emeritus of electronics and communication engineering at Birla Institute of Technology, Mesra, Ranchi. He has more than 40 years of experience in teaching and research in antenna and wave propagation. He has published several books and papers on this topic.

What is the latest edition of the book? The latest edition of the book is the third edition, which was published in 2003 by Satya Prakashan.

Is there a solution manual for the book? There is no official solution manual for the book, but you might find some unofficial solutions online or on some websites.

How can I contact the author or the publisher? You can contact the author or the publisher by visiting their websites or sending them an email. The author's email is kdprasad@bitmesra.ac.in. The publisher's website is http://www.satyaprakashan.com/.

What are some other books on antenna and wave propagation? Some other books on antenna and wave propagation are:

Antenna Theory by C.A. Balanis

Electromagnetic Waves and Radiating Systems by E.C. Jordan and K.G. Balmain

Antennas by J.D. Kraus and R.J. Marhefka

Antennas for All Applications by J.D. Kraus, R.J. Marhefka, and A.S. Khan

Microwave Engineering by D.M. Pozar

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