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Richard Fry wrote:
"Cecil Moore": Jimmie D wrote: One such mistake is calling a 4 ft long antenna that has a coil to make it resonate on the 10M band a "10M loaded 1/4 wavelength antenna". They should be more careful and specify that they are talking about electrical lengths, not physical lengths. They also should point out that, although a radiator physically/electrically shorter than needed for first self-resonance can be "loaded" to resonance, this does not mean that loaded and self-resonant radiators perform equally well in an installed system. In some applications there can be as much as a 100:1 difference in their radiated powers, for a given power at the transmitter output connector. Good point, Richard. An antenna's ability to "load" is proportional to its electrical length. An antenna's ability to radiate seems to be proportional to the physical length of the antenna that is carrying the highest current. In 75m shootouts, the mobile antennas with the loading coil furtherest away from the feedpoint (closest to top-loaded) generally won the shootout. -- 73, Cecil http://www.w5dxp.com |