The paper *A Closer Look at Vertical Antennas With Elevated Ground Systems*, by Rudy, N6LF goes into great detail on the subject. Referring to Figure 13, which compares Ga (Average Gain) for radial heights of 8' and 0.5' at 3.65 MHz, Rudy shows a gain difference of just 0.2 dB. This is for a 68' radiator. Figure 16 shows the height-to-gain curve becoming asymptotic at a radial height of 0.01 wavelength. This is 5' for us topbanders. Figure 17 is a similar graph for, I assume, the 40 meter band, and shows that at radial height of half a foot things start to look good. Rudy strongly advocates using many elevated radials to avoid pattern asymmetry caused by unequal radial RF current.
https://rudys.typepad.com/files/elevated-ground-systems-article-final-version.pdf At home I have a 40/80 meter vertical having two resonant radials per band 8' above ground. For portable 160 meter operation NH6V and I have used a slant wire vertical with two resonant radials 10 to 20 ft. above ground. Dave KH6AQ On Thu, Jan 4, 2024 at 5:01 PM Radio KH6O <[email protected]> wrote: > Attached is an interesting research paper by Clarence Beverage. > > -- > 73, > Jeff KH6O > _________________ > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
