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How Can you Make a VHF TV Antenna for an Attic
Correction:
Roy Lewallen wrote: . . . This is true. However, in almost all cases the loss caused by using wire, even very small wire is still negligible. Exceptions are antennas which are very short in terms of wavelength, particularly at low frequencies. As frequency increases, the length of an antenna of equal performance decreases in direct proportion. However, the loss decreases only as the square root of frequency. So antennas of the same wavelength size become proportionally less lossy at higher frequencies. . . . Loss increases, not decreases, with frequency, in proportion to the square root of frequency. But the conclusion stated in the last sentence is correct. If you quadruple the frequency, wires become four times shorter for the same type of antenna. Assuming you keep the same wire size, this length change results in one quarter the loss resistance. The decrease in skin depth due to quadrupling frequency causes an increase of loss only by a factor of sqrt(4) = 2. The net result is that quadrupling the frequency cuts the total loss in half. Roy Lewallen, W7EL |
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