Guide to Antennas: Article index and introduction

Article index and introduction (this page)

1. Radio signals on the move

2. Antenna basics

3. Wire, connection, grounds, etc.

4. Marconi and other unbalanced antennas

5. Doublets, dipoles, and other Hertzian antennas

6. Limited space antennas

7. Large loop antennas

8. Wire array antennas

9. Small loop antennas

10. Yagi beam antennas

11. Impedance matching

12. Simple antenna instrumentation and measurements

13. Getting a 'good ground'

INTRODUCTION

If you are interested in amateur radio, short-wave listening, scanner monitoring, or any other radio hobby, then you will probably need to know a few things about radio antennas. This guide is intended for the radio enthusiast - whether ham operator, listening hobbyist, or radio science observer - who wants to build and use antennas for their particular requirements and location. All of the antennas in this guide can be made from wire, even though it’s possible to use other materials if you desire.

These antennas have several advantages. One of he most attractive is that they can provide decent performance on the cheap. As one who has lived through the experience of being broke, I learned early to use bits of scrap wire to get on the air. My first novice antenna back in the late 1950s was a real patched-together job - but it worked really well (or so I thought at the time!).

Another advantage of wire antennas is that they are usually quite easy to install. A couple of elevated supports (tree, roof, mast), a few meters of wire, a few bits of radio hardware, and you are in the business of putting up an antenna. As long as you select a safe location, then you should have little difficulty erecting that antenna.

Finally, most high-frequency (HF) short-wave antennas are really easy to get working properly. One does not need to be a rocket scientist - or professional antenna rigger - to make most of these antennas perform as well as possible with only a little effort. There is quite a bit of detailed technical material to digest if you want to be a professional antenna engineer, but you can have good results if you follow a few simple guidelines.

ANTENNA SAFETY

Another issue is electrical safety. Don’t ever, ever, ever toss an antenna wire over the power lines. Ever. Period. Also, whatever type of antenna you put up, make sure that it’s in a location where it cannot possibly fall over and hit the power line.

The last issue is to be careful when digging to lay down radials. You really don’t want to hit water lines, sewer lines, buried electrical service lines, or gas lines. I even know of one property where a long-distance oil pipeline runs beneath the surface. If you don’t know where these lines are, try to guess by looking at the locations of the meters on the street, and the service entrance at the house. Hint: most surveyors plans (those map-like papers you get at settlement) show the location of the buried services. They should also be on maps held by the local government (although you might have to go to two or three offices! The utility companies can also help.

A NOTE ABOUT UNITS AND PRACTICES

This guide was written for an international readership. As a result, some of the material is written in terms of US standard practice. Wherever possible, I have included UK standard wire sizes and metric units. Metric units are not in common usage in the USA, but rather we still use the old English system of feet, yards, and inches.

Although many Americans (including myself) wish the USA would convert to SI units, it’s not likely in the near future. UK readers with a sense of history might recognize why this might be true - as you may recall from the George III unpleasantness, Americans don’t like foreign rulers, so it’s not likely that our measuring rulers will be marked in centimeters rather than inches.

For those who have not yet mastered the intricacies of converting between the two systems:

1 inch = 2:54 centimeters (cm) = 25:4 millimeters (mm)

1 foot = 30:48 cm = 0:3048 meter (m)

1m = 39:37 inches = 3:28 feet.

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