Evaluation of 3-N Site Attenuation by the Moment Method

The 3-m site attenuation is calculated by the moment method for vertically polarized waves from 76 to 1000 MHz as well as for horizontally polarized waves from 30 to 1000 MHz, using the specifications outlined by the CISPR and the FCC. The moment method offers a newer more precise treatment of the incident angle to the ground when applied to the theoretical analysis of site attenuation. Calculations are carried out for two kinds of ground conditions. One assumes a metal ground plane (ideally perfect conductor) and the other, a natural earth ground (medium dry). The electrical characteristics of the ground presented in the CCIR Recommendation [15] are adopted for these calculations. Experimental values obtained on a natural earth ground plane using commercial tuned-dipole antennas showed agreement with theoretical values within ± 3 dB.