Distortions of receiving antenna radiation patterns on tropospheric paths

Distortions of instant antenna radiation patterns beyond a line-of-sight are investigated by means of mathematical modelling. The model of the inhomogeneous atmosphere includes a limited number of local inhomogeneities in the form of bumps of the random field above the predetermined level. The results of the field calculation of directional antennas using the proposed medium model are consistent with experimental data about distortions of instant radiation patterns in main and side lobes.

1. Introduction

Distortions of radiation patterns (RP) of antennas on tropospheric paths had been extensively studied during the experimental investigations of long-distance tropospheric wave propagation, carried out under the leadership of Y.S. Shifrin [1]. Monograph [1] contains the results of processing of about 1000 records of “instant” radiation patterns (IRP) of receiving antenna and characteristics of mean RPs obtained by averaging signals at the antenna output over 5..10 minutes. IRPs of the receiving antenna for the same conditions have been calculated in [2] using the Kolmogorov-Obuhov model and the energy spectrum of fluctuations in the form . These results agree with experimental data [1] in the IRP main lobe, whereas differences in side lobes are large and can not be reduced by changing characteristics of the inhomogeneous medium within the said model.