Antenna for 40 Meters

Antenna for 40 Meters

Antenna: 40 meters, Range: 7.0 to 7.3 MHz

Good 40 meters antennas are easy to build with nothing more than readily available materials. Since 40 meters covers the frequency range of 7.0 to 7.3 MHz you can use a few algebraic formulas to compute antenna sizes.

Antennas for 40 meters are used as verticals and dipoles with great success. 40 meters antennas are a bit large as verticals but dipoles for 40 meters are quite manageable. A dipole for 40 meters can easily be strung between two tall trees located near a survivalist camp.

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 40 meters is approximately 32 feet 6 and 9/32 inches in length. This antenna measurement can be used for either a vertical antenna for 40 meters or a horizontal antenna for 40 meters.

Propagation is very good on 40 meters for local and DX work. Intercontinental contacts are very common on voice, Morse code and the digital modes. Of all the bands available it might be said that 40 meters is the most versatile.

40 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.