HF Antennas Wire antennas typically represent the cheapest and easiest to build of large antennas and usually have lower gain figures. Directional or beam antennas often have high gain, and are more expensive and complicated in design, the most common being the Yagi. |
VHF/UHF Antennas Primarily used for short range or line-of-sight communications from 30MHz up to 1.2GHz, these are the smaller lightweight antennas used to access repeaters, voice & data links, and weak signal work, such as EME (moonbounce), SSB and satellites. |
Satellite Antennas Covering VHF to microwave, from small hand-held antennas, to dishes and large arrays. Usually directional, high-gain and fully steerable antennas. |
Wire Antennas Cras |
Capsule Story Cras |
Ham Radio Antennas
Antennas are to radio as speakers are to hi-fi. Your signal is only as good as the antenna radiating it. A high gain antenna can give a 100W transmitter as big a signal as a 1,000W into an antenna with little or no gain.
In this business size matters, and location, location, location. Unfortunately, not everyone with a radio has the real estate, elevation or budget for an ideal antenna system. Many newer residential communities don't allow visible antennas at all, so now we have a whole new breed of "stealth" antennas. But, for those with big budgets and the real estate to go with it, the sky's the limit!
The main variable when it comes to antenna size, is operating frequency or band. Rule of thumb is the higher the frequency (shorter wavelength), the smaller the antenna. Imagine looking at a series of ocean waves from the side. The frequency is how often the peak of a wave passes a particular point, say a buoy. The wavelength is the actual distance between peaks. Radio waves are they same, but invisible to the human eye. For antennas to effectively radiate, they must be electrically equivalent or "resonant" to the wavelength of the desired transmitter frequency. Simple, right? The basic theory is rather simple, however designing and building antennas has been called "magic" or "voodoo" by many. It helps to have a degree in physics, or at least engineering.
HF = High Frequency, VHF = Very High Frequency, UHF = Ultra High Frequency, and so on. The term "shortwave" is kind of misleading though. It's actually synonymous with HF (3~30MHz). Just for reference, cellular phones operate at either 800MHz or 1.8GHz. Citizen's Band, or CB is in the 27MHz range (11 meter wavelength) - within the shortwave domain. The term "shortwave" was coined back in the days when anything above 3MHz was thought to be useless. Imagine that!
I've broken down the ham radio antenna reference by frequency, and type.