TWO WIRE RHOMBIC ILLUMINATOR PERFORMANCE AS PREDICTED BY THEORETICAL AND NUMERICAL MODELS

Abstract

The two wire rhombic illuminator (RI) is a rhombic wire antenna located over a ground plane which is used to generate near uniform electromagnetic fields over a specified working volume located below the antenna. The RI can be modeled as a simple two-wire transmission line at low frequencies but the transmission line model becomes inadequate at higher frequencies due to the enhanced radiation properties of the antenna. The performance of the RI including radiation effects is evaluated numerically using the Numerical Electromagnetics Code (NEC-2) and compared to that of the transmission line model. The antenna in the presence of a perfectly conducting ground plane is analyzed at frequencies ranging from 1 MHz to 500 MHz. Various segmentation schemes are utilized in order to accurately predict the performance of the RI at frequencies where the dimensions of the structure are very large in terms of wavelength. [Vol. 9, No. 1 (1994), pp 88- 101]