Antenna: 15 meters, Range: 21 to 21.45 MHz
Good 15 meters antennas are easy to build with nothing more than readily available materials. Since 15 meters covers the frequency range of 21 to 21.45 MHz you can use a few algebraic formulas to compute antenna sizes.
In the case of antennas for 15 meters you can see the antenna size begin to increase but not too large. A survivalist can make good use of a dipole antennas for 15 meters. A dipole is nothing more than taking the whole length of wire and cutting it in half. Each piece is separated with the shield of the coaxial cable connected to one wire end while the center conductor of the coax is connected to the other. Dipole antennas for 15 meters are easy to deploy as you can throw a couple of ropes up into trees or other structures and pull the antenna up and out of the way.
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 15 meters is approximately 11 feet 15/32 inches in length. This antenna measurement can be used for either a vertical antenna for 15 meters or a horizontal antenna for 15 meters.
15 meters is a great band and could be pressed into service for either day or night time use depending upon the current sunspot cycle.