Rapid calculation of near-field fluence of HPM antennas

The calculation of near-field fluences of high-power microwave (HPM) antennas is reviewed. Near-fields close to large square or circular antennas are calculated rapidly using the geometric theory of diffraction; one specular and two edge-diffracted rays are used. In the principal planes, accuracy is roughly 2 dB at the -40-dB level, for both uniform and tapered excitations. A universal power density curve is obtained along a line parallel to the aperture, when the distance to the line is normalized by 2D²/λ, and the transverse distance is normalized by D (where λ is the radiation wavelength and D is the aperture width). Diagonal plane fields are calculated using equivalent edge currents via a single numerical integration. Fluence envelopes are obtained in the sidelobe region simply by summing the magnitudes of the two edge rays