There are many different types of amateur radio antennas from which to choose. Some options include dipole antennas, vertical and whip antennas and quad antennas. There even are collapsible antennas to use in mobile situations. Space constraints, frequency of operation and, of course, budget restrictions are important factors to consider before deciding on an antenna. For amateur radio operators living in private communities, antenna height may be a concern — the lower the frequency, the longer the antenna.
The dipole antenna is typically one of the easiest of all amateur radio antennas to construct. Many amateur radio, or ham, operators use variations of this antenna to operate from 33 feet (10 meters) to 262 feet (80 meters). For use on multiple bands, an antenna tuner is required to match the transmitter to the antenna. A simple dipole antenna can be constructed from copper wire and two insulators. Dipoles often are ideal for attics, or can be strung between two trees. Some are constructed using metal tubing and can be made to rotate in order to get signals from any direction. Yagi antennas are a more sophisticated version of the dipole and are much more expensive. They offer more gain than a dipole, however. A good example of a yagi antenna is the old standard television antenna.
Amateur radio antennas for limited space are popular. Vertical antennas can fit this bill nicely. An important feature of verticals is they can be loaded down. This means their physical length is electrically shortened by a coil installed at the base of the antenna, which will offer more frequency range without the unwieldy height. Mobile whip antennas are a good example of a vertical antenna for small-spaces — they can even be used from a car. The mobile whip antenna can be mounted on a porch, in an attic, or portable mounted outside a window. It can even be ground mounted. Vertical antennas can be used on multiple frequencies along with an antenna tuner. Collapsible vertical antennas can be an excellent choice for in-field use, as they can be easily taken down and generally occupy little space for easy storage.
Another alternative antenna is the quad. It provides good gain, and can work well at lower heights. An advantage this antenna has over other types is that multiple band use is rather easy to achieve. There are several types of quad antennas. The cubic quad is very popular among hams.
When operating on frequencies above 30 megahertz, the antennas are greatly reduced in size. This is a function of the higher frequency wavelengths. While distance contacts are not as frequent as below 30 megahertz, the exceptional signal quality is welcome. Many hams like to experiment with homemade antennas, while others choose to purchase their antennas. More information regarding antennas can often be found at amateur radio associations, such as the American Radio Relay League in the United States.