RF Characteristics of thin dipoles

Abstract

This paper considers the average bistatic scattering cross section of thin cylindrical dipoles as a function of frequency, bistatic angle, and transmitting and receiving polarization. The averaging is over all orientations of the dipole with all orientations equally likely. Section II is essentially tutorial, approaching the problem of scattering cross section from the equivalent circuit point of view. Using this approach, the maximum scattering cross sections of lossless dipoles in the Rayleigh region and at the first and second resonances are derived. Section III presents a novel method of predicting cross section at the first resonance with the effect of loss included. Numerous measurements indicate that this method is widely applicable. Section IV describes our microwave scattering range and the results of measurements made on dipoles resonant at X band. In Section V the averaging of cross sections is considered. The average bistatic cross sections for resonant half-wave and full-wave dipoles are plotted vs bistatic angle for various transmitting and receiving polarizations. These results, which are new, were obtained using a digital computer. The average cross section for short (Rayleigh region) dipoles is also obtained as a function of bistatic angle for various polarizations. Section VI is a summary of parameters of the West Ford dipoles.