RADIATION DIRECTIVITY of A BURIED LEAKY COAXIAL CABLE IN A GUIDED RADAR SYSTEM

The theoretical and experimental investigations of the radiation directivity of the buried leaky coaxial cable (LCC) are presented. The theoretical model of two coupling waveguides, external of which consists sub-soil medium, is introduced to describe interactions of two modes, external and internal which determine the working characteristics of such a leaky coaxial cable. The theoretical analysis shows, that the main parameters affecting the performance of such a guided radar system are the attenuation, which limits the longitudinal range of LCC, and coupling. which determines the overall sensitivity and field pattern of radar system. The coupling coefficients depend on the internal and external parameters of LCC and sub-soil medium. Attenuation is relatively easy to measure by simple insertion loss techniques. Coupling is the measure of the signal accessibility at a given radial distance outside the cable and, being very dependent on the particular installation and environmental aspects. The vertical and the horizontal distribution of radiation along the cable are examined experimentally by use of the loop of the LCC buried at the depth 10-15 cm. The electric field intensity distribution both along and accross the cable at the height -0.8 m above the ground is measured The comparison between experimental data and theoretical prediction of radiation directivity of LCC for guided radar system is presented.