Antennas for 75 Meters

Antennas for 75 Meters

Antenna: 75 meters, Range: 3.6 to 4 MHz

Good 75 meters antennas are easy to build with nothing more than readily available materials. Since 75 meters covers the frequency range of 3.6 to 4 MHz you can use a few algebraic formulas to compute antenna sizes.

As you can see, the size of a quarter wave antenna for 75 meters is rather large at almost 64 feet for 3.665mhz. For survivalist use a vertical antenna for 75 meters is impractical while a dipole for 75 meters could be quite useful. The band known as 75 meters is actually part of the 80 meter band but is designated as voice only.

This formula: 234/f can be explained by dividing 234 by the desired frequency in megahertz which will give you the length, in feet, of a 1/4 wave antenna. This formula isn’t exact in that it assumes the radiating element is infinitely small. What this means is if the radiating element was one inch in diameter then the resonant length of the antenna would be a little shorter than the calculated one given by the formula gives you.

Using the formula above you will soon see that an antenna for 75 meters is approximately 63 feet 10 and 3/16 inches in length. This antenna measurement can be used for either a vertical antenna for 75 meters or a horizontal antenna for 75 meters.

75 meters is a great band for regional interstate and intrastate communications. It is quite capable of good intercontinental communications as well but generally requires an amplifier to do so. 75 meters and even 80 meters should also be a part of a survivalist communication system.

75 meter antenna

Beam Antennas

Beam Antennas

Beam Antennas.
We have all seen at least one of these antennas around. They are usually on top of a tower or at the very least on the roof of a tall building. Beam antennas need to be a good distance up in the air in order for them to work adequately. A good height for beam antennas is generally 40 feet high but you will see them on top of towers over 100 feet tall. Many times on these larger towers you will see more than one of these beam antennas with each antenna dedicated to a certain frequency. One point of interest with beam antennas is that the smaller the antenna the higher the frequency it is used on.

The use of beam antennas in survival environments is not unheard of but the logistics of the tower, the rotator, and the antenna itself would likely be enough to prevent their use in most survivalist operations. In case you’re wondering, the rotator mentioned earlier is to turn the antenna in the direction of the station you wish to communicate with. By their design a beam antenna’s most powerful signal is heard from the front of it and the best way to block an offending signal is to turn a beam so the side or back of the beam is directed at the offender.

Beam antennas are not all created the same, some are made a YAGI BEAM ANTENNAfrom aluminum tubing and are called yagi antennas. Another design for beams is that of a quad antenna. This antenna consists a 2 large arms crisscrossed and then a wire connects to the end of each of the arms. This antenna has an excellent reputation in the amateur radio community but it is quite a bit larger than a yagi antenna.

So before you contemplate the use of a beam antenna at your compound or even at your base station you need to total up the costs as well as the work involved in setting up a beam antenna. If you are working portable then you likely will not consider a beam antenna.