[TowerTalk] Radial Question

[Dennis W0JX]

The effect of the earth on the radial generally is to detune it and make it longer electrically than it is. Perhaps Frank W3LPL can add something here as to why he recommends 70 feet.
As for elevated radials. many studies have concluded, going back as far as Les Moxon, that quarter-wave elevated radials are about the worst possible length you can make them. This particular length makes it very difficult to obtain equal currents in each radial. Dick Weber, K5IU, wrote an excellent article on this topic, stating that ideal lengths are 60 degrees (or about 2/3rds of a quarter wavelength) loaded by a single small coil, or 120 degrees (about 4/3rds of a quarter wavelength) tuned by a variable capacitor, are ideal lengths. Of course, a multi-band vertical complicates matters and would require a loading coil for each band.
73, Dennis W0JX