MODELLING BY NEC OF AN HF LOG-PERIODIC ANTENNA

Abstract

The Numerical Electromagnetics Code (NEC) is a computer code for analysing the electromagnetic response of an arbitrary structure consisting of wires and surfaces in free space or over a ground plane. It is based on the application of the Method of Moments to solve the electric field integral equation. A practical application of NEC which involved calculation of the impedance of a vertically polarised HF log- periodic antenna and comparison with measurements is described. A technique for improving the accuracy of the numerical calculations is discussed in addition to methods for accurately measuringmpedances of antennas employing balanced two-wire transmission line feeders. [Vol. 2, No. 2, pp. 103-111 (1987)]