FEEDING ANTENNAS
Volumes 1 & 2

FEEDING ANTENNAS
Volume 1: About Baluns

ABOUT THIS BOOK SERIES
fter an RF signal has been generated in a transmitter, some means must be used to radiate this signal through space to a receiver. The device that does this job is the antenna. The transmitter signal energy is sent into space by a transmitting antenna; the RF signal is then picked up from space by a receiving antenna. The RF energy is transmitted into space in the form of an electromagnetic field. As the electromagnetic field arrives at the receiving antenna, a voltage is induced into the antenna (a conductor). The RF voltage induced into the receiving antenna is then passed into the receiver and translated back into the transmitted RF information.

The design of the entire antenna system is very important in a transmitting station. The antenna must be able to radiate efficiently so the power supplied by the transmitter is not wasted. An efficient transmitting antenna must have exact dimensions. The dimensions are determined by the transmitting frequencies. The dimensions of the receiving antenna are not so critical for relatively low radio frequencies. However, as the frequency of the signal being received increases, the design and installation of the receiving antenna become more critical. An example of this is a television receiving antenna. If you raise it a few more inches from the ground or give a slight turn in direction, you can change a snowy blur into a clear picture.

The feedline link between the antenna and the transmitting/receiving equipment is often the most mysterious part of the system. Therefore, this book assembles many articles from past issues of antenneX to provide the reader with a wealth of ideas that may enhance understanding and provide practical ideas for achieving goals that are common to feedline concerns.

In this 2-Volume book series, we primarily deal with the feeding aspects of an antenna system, which covers the area between the transmitter and the antenna. This 200-page Volume 1 specifically deals with the use and application of various types of baluns, which happens to be a much more complicated component of the feedline than one would think whether one is a novice or expert. There are many different types, designs and methods of placement of the balun for the wide variety of antennas and their setups as well as environments. Numerous examples are shown with diagrams.

For Volume 2 about antenna networks, please scroll further down.

ABOUT THE AUTHORS - Volume 1
We have some of the finest authors and antenna experts whose works on which this book is based. We have attached a brief professional biography of each author by order of first appearance in the book: Click here for Authors

TOPICS COVERED IN VOLUME 1

FEEDING ANTENNAS
Volume 2: Matching Networks

n Volume 2 of this book series, we shall discuss a wide variety of matching methods, including numerous designs, some frequency specific. Feeding an antenna is supplying energy to the appropriate element or elements in a series connection with the element, at a position on the element prescribed by the design. In pure terms, one places the energy source at this position. More realistically, one uses a transmission line between the actual energy source and the feedpoint position of the element. In some cases, one may place a matching network at the antenna terminals, with the transmission line connected to the input side of the network. For complex arrays with multiple fed elements, the feed system may use a combination of transmission lines and networks to establish specific relative current magnitudes and phase angles at each designated feedpoint.

There are many types of networks and some are antenna-type specific. In the chapters of this book many of these designs will be found, from basic to complex, some even experimental. One may have a great deal of fun experimenting with this useful antenna feeding component as well as the location of the feed connection.

Simply defined, an antenna network is a configuration of inductively and capacitively reactive components. The most fundamental arrangement is the L, with a series component of one type and a parallel or shunt component of the other type. More complex forms, such as PI and T networks are combination of L networks. Volume 2 delves into all of these in theory, construction and use.

More specifically, antenna networks have three main functions:

1. Networks can be designed to have different input and output impedance values and therefore are useful in transforming impedances. Special forms of them appear at the antenna terminals (such as the beta and the gamma match) to transform the antenna terminal impedance to a value that coincides with the desired main feedline impedance. The network antenna tuner in common use today is an example of a network used to transform a wide range on impedance values to the 50-Ohm value specific to most amateur radio and other equipment.

2. Networks act as high or low pass filters. When the series component is inductively reactance and the shunt component is capacitively reactive, we have a low-pass filter. If we reverse the positions of the reactance types, we have a high-pass filter. We may makes some network legs complex—usually in the form of series or parallel resonant circuits—to sharpen the filtration or to create band-pass or band-stop filter. (Some rudimentary audio filters use combination of one reactive leg and one resistive leg.)

3. Networks always show at the output side a change in the phase angle of the AC (or RF) signal. This phenomena is useful in the development of phased arrays that are dependent for their directional properties on the relative magnitude and phase angle of the currents at the respective feedpoints of the elements composing them.

ABOUT THE AUTHORS - Volume 2
Again, with this Volume 2, we have some of the finest authors and antenna experts whose works on which this book is based. We have attached a brief professional biography of each author by order of first appearance in the book: Click here for Authors

TOPICS COVERED IN VOLUME 2

HOW TO ORDER THESE BOOKS
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VOLUME 1	Catalog # Vol 1	Regular Price	Catalog # Vol 1 & 2	Both Volumes
eBOOK CD-ROM ORDER FORM	BOD-010	$24.95 USD	BOD-012	$42.95 USD
eBOOK DOWNLOAD ORDER FORM	BDL-010	$22.95 USD	BDL-012	$39.95 USD
VOLUME 2	Catalog # Vol 2	Regular Price	Catalog # Vol 1 & 2	Both Volumes
eBOOK CD-ROM ORDER FORM	BOD-011	$28.95 USD	BOD-012	$42.95 USD
eBOOK DOWNLOAD ORDER FORM	BDL-011	$26.95 USD	BDL-012	$39.95 USD