Bistatic scattering cross section of chaff dipoles with application to communications

The variational method of computing radar scattering cross sections has been applied to the bistatic scattering cross section for chaff dipoles. The average cross section was calculated for three distributions of dipole orientation; uniform, horizonal, and vertical. The geometry considered was for dipoles located near one terminal of a two terminal radio link such that the azimuth and elevations angles of the far terminal were small. Measured values of bistatic cross section were within about 3 dB of predicted values for measurements at a frequency 5652 MHz. Fading rates from 5 Hz to 25 Hz were measured. Space diversity distances were of the order of 2 to 5 feet for this particular 50-mile link.