Iterative calculation of ship-borne HF antenna performance

Abstract

The computer program NEC-2, which calculates the currents on wire-grid models by the method of moments, is modified to analyse structures which consist of a collection of disconnected substructures. The matrix equation for the currents is solved by means of iteration between the substructures using the Siedel method. The convergence is accelerated using an extrapolation technique. For a structure with 708 segments divided into six substructures, the new program NECK took only ⅓ of the time of NEC. The program is used to calculate the impedance and radiation patterns of ship-borne antennas in the presence of a funnel, masts and other antennas, all on a perfectly conducting ground plane. Comparisons of the results obtained using the two codes show good agreement.In addition, a programme of electromagnetic measurements was carried out to validate the use of wire-grid computer codes in the simulation of antenna characteristics and scattering phenomena in the HF band. The results show favourable agreement.