Antenna Advice - Introduction @ DXing Info

At Radio Netherlands, we get several thousand questions a year about antennas. This feature is designed to explode some of the myths about antennas and offer some practical advice.

If you look at books about this subject, they quite often have a huge antenna on the front cover. This leads to the general impression that a large antenna will pick up a stronger signal and therefore give better reception of the chosen signal. In this feature we hope to show that the location and orientation of the antenna is much more important than the size. The claims that many manufacturers put in their brochures are only half the story.

We will examine the factors that influence shortwave reception, address the question of whether an external antenna will always provide better reception, discuss passive and active antennas, look at some antenna accessories and review some antenna safety tips.

Two appendices are included: a bibliography and a list of names and addresses of publishers, vendors and manufacturers. We would like to hear of your experiences. We have used our own to compile this document, together with a great deal of input from shortwave listeners around the world.

Passive Antennas

for DXing

Experimentation with antennas has existed since radio began. One of the basic antenna forms is a dipole, whose length is half that of the wavelength it is to receive. The center of the dipole is cut so that a coaxial cable can be connected. At this length the antenna impedance best matches that of the connecting cable, namely 50 ohms, and there is a maximum transfer of energy.

The dipole may be mounted horizontally, as an inverted-vee (with the center higher then the ends), or as a sloper (one end is mounted higher than the other).

Active antennas solve a number of problems -- space and government or deed restrictions -- immediately.

Few people have the space to hang a dipole of some 30 meters to match their interest in the 60 meter tropical broadcast band. Additionally, it seems that many local government authorities around the world are becoming more restrictive in their attitude towards outdoor antennas. Pick up almost any electronics magazine and you'll find someone advertising a solution.