15 Meters: Full Details

The 15 meter or 21 MHz band is a core amateur radio frequency band, which spans 21 to 21.45 MHz and is allocated to radio amateurs as primary users worldwide. 15 meters is considered a DX band, most useful for inter-continental communication during daylight hours, especially in years close to the solar maximum, since the 15 meter wavelength propagates primarily via reflection by the F-2 layer.

Because the frequency is the third harmonic of the 40 meter amateur band, it is possible to obtain a close impedance match using an antenna cut for 40 meters on 15 meters, as well. Usually, though, users of the 15 meter band employ rotatable, multi-element directional antennas such as a Yagi antenna or Quad antenna to improve their communications with the particular area of the world they wish to reach.