Analysis of the Sea Surface Influence on the Shape of Microwave Spiral Antenna Radiation Pattern

The article presents an analysis of the influence of water surface on the radiation pattern of spiral antenna of the S-, C-, X- and Ku-bands. Antenna is located in a normal plane of the water surface. The results of simulation of the radiation pattern of such antenna at different heights of its location above the conducting surface are presented. The analysis of the influence of the found distortions in the shape of antenna pattern on the quality of direction finding of radio sources operating in different frequency bands was performed. Recommendations for data processing to improve the quality of direction finding were developed.

I. Introduction

Modern radio direction finding (RDF) means solve a wide range of tasks in various geographical conditions. These conditions include, among others, the open sea. The sea surface is a conducting medium. Antenna systems of sea-based RDF means can be located at a small height from this surface in cases when the design of the carrier requires it. Such an arrangement inevitably leads to a distortion of radiation patterns of antennas forming the antenna system of the RDF complex. At the same time, the accuracy of direction finding of the RDF complex directly depends on the degree of correspondence of the direction finding function of the antenna system, obtained under laboratory conditions, with the function corresponding to the operating conditions of the RDF complex [1]. Thus, there is a need to estimate the nature of the distortion of the radiation pattern of antennas located near the sea surface.