A numerical investigation of ground plane effects on biconical antenna factor

An accurate antenna factor (AF) is highly desirable for radiated emission and/or normalized site attenuation measurements. An AF is often measured in the presence of a perfectly conducting ground plane, such as prescribed in ANSI C63.5. For a receiving antenna, the ground plane affects the electromagnetic field by altering the magnitude and distribution of the incident field. It also introduces mutual coupling between the antenna and its image beneath the ground. These effects can cause a different measured AF when the same antenna is polarized horizontally or vertically with respect to ground, or calibrated at a different height. Using a biconical antenna, the authors conduct a numerical analysis to quantify the influence of the ground on the AF.