If such long spans cannot be accommodated, smallerĪntennas will still give adequate receive-only performance down to about half of their lowest design frequency. For the higher portion of shortwave (5 to 30 MHz), this antenna will be roughly 20 m long, with a spacing of 60 cm. Will be roughly 33 m long, with conductors spaced 1 m. For example, an antenna for the lower portion of shortwave (say, 3 to 18 MHz) Such an antenna is usable for both local and medium-long distance communication across a frequency range of about 1:6. In order to make it roughly omnidirectional, it is ideally strung sloping at an angle of 20 to 40 degrees from horizontal, but will also function satisfactorily if mounted horizontally, as long as it is pulled-out in a reasonably straight line. The resistor absorbs a growing portion of the RF power (either captured from the air or supplied by a transmitter) as the operating frequency nears the lower limit of the design range. Terminated in the middle of the upper conductor with a 400 Ω non-inductive resistor, rated to safely absorb at least 1/3 of the applied transmitter power. This provides an acceptable all-frequency match to commonly available 75 Ω coaxial cable.
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