Antenna to ground-plane mutual coupling measurements on open-field test sites

There is documented disagreement as to whether or not mutual coupling between broadband antennas and the conductive ground plane has a significant effect on electric field measurements made on open-field test sites. Methods for measuring the effect of such mutual coupling are described. Experimental results indicate that the effects are significant-as much as 2 dB or more-for biconical antennas used at frequencies from 30 to 300 MHz but insignificant-less than 0.5 dB-for log-periodic antennas used at frequencies from 300 to 1000 MHz. Experimental results are presented for horizontal polarization only