Directivity and effective radius of an electrically large EUT with attached wires

This paper investigates the influence of wires attached to an electrically large EUT on the estimates for the directivity. A rectangular slotted metallic enclosure was considered as an EUT. For different cable configurations the simulated current distribution and the maximum directivity Dmax were determined in the frequency range from 1GHz to 6GHz by a numerical simulation technique. The simulation results reveal that Dmax for different cable configurations with the same length shows similar tendency and minor difference. The effective radius was obtained and compared based on the simulated directivity according to different theoretical models. It was shown that the estimation of the effective radius would be much more practical using Traveling Wave Antenna and Standing Wave Antenna theory.