Developing this topic a little more, the link below shows a NEC4.2 model of a 1/4-wave, vertical monopole driven against a set of 4 x 1/4-wave horizontal wires used as an elevated counterpoise. The base of the monopole and the elevation of the radial wires are set to 4.9 meters, as in the Culpepper system I posted earlier in this thread (Sat, 2 March 2013 at 04.33:34 -0600). The relative amplitudes and phases are shown for each conductor. Frequency is 1490 kHz. The system was modeled over perfect earth.
This system produces an inverse distance groundwave field of ~313 mV/m at 1 km for 1 kW of applied power. This is the maximum theoretical field possible for those conditions for a perfect, series-fed, 1/4-wave monopole base-driven against a perfect ground plane. The azimuth radiation pattern is perfectly circular. This is as expected, because the only conductor producing useful far-field radiation is the vertical monopole, itself. There is no physical reason why that radiation should be other than omnidirectional, at all elevation angles. But while the performance shown by this NEC model is identical to that of a perfect monopole with its base attached to a perfect, flat ground plane of infinite extent, none of the r-f current flowing on the vertical section has needed to flow through the earth to reach the monopole. In fact, the NEC model HAS no structural connection to the earth ! No earth currents will flow along the vertical monopole in such elevated systems even when they are installed just above a non-perfect ground plane, such as the earth. This illustrates how such an elevated system using only 4 x 1/4-wave horizontal wires as a counterpoise can equal the performance of a conventional 1/4-wave monopole using as many as 120 x 1/2-wave radials buried in real earth. http://i62.photobucket.com/albums/h85/rfry-100/Culpepper1_zps566188da.jpg RF _________________ Topband Reflector