Measurement of antenna beam patterns in polarization and phase and of amplitude-phase distributions by the correlation method using extraterrestrial sources of radio emission

Abstract

Questions of the measurement of antenna beam patterns in amplitude, phase, and polarization by the correlation method from extraterrestrial sources of radio emission are discussed. An expression for the correlation matrix is obtained with allowance for the polarization properties of the antennas and the emission of the radio source. An exact equation is given for the digitai filtration of the results of measurement of an antenna beam pattern. Using various means of representation of information, experimental data are given on measurements of an antenna beam pattern and the reconstruction of the amplitude-phase distribution of the field in the antenna aperture. The correlation method of determining antenna characteristics from extraterrestrial sources of radio emission [1-6] is very effective in the measurement of the parameters of high-gain antemuas. In contrast to the traditional means of measuring antenna beam patterns (BP) from discrete sources of radio emission using radiometric receivers, in the correlation method one uses correlation analysis of the signals of the investigated antenna and an auxiliary one, which increases the sensitivity of the system in the measurement of low levels of antenna BP and allows one to measure BP in phase and polarization. In [1-6] questions of the choice of sources of radio emission and the treatment of experimental results are discussed and the makeup of the apparatus and the experimental data of measurement of BP in amplitude using the correlation method are presented. Questions of the digital filtration of the results of BP measurements by the correlation method and a means of measuring the polarization characteristics of antennas from the randomly polarized emission of discrete radio sources are investigated in the article being offered; experimental data are presented on an investigation of BP in phase and cross-polarizati on, the measurement of which presents certain difficulties, as pointed out in [2, 5]. The set of measured BP in amplitude and phase (the complex BP) was used to reconstruct the amplitude-phase distribution (APD) of the field in the antenna aperture. 1. Basic Theoretical Equations To determine BP in polarization one must know the connection between the signal at the output of the correlation receiver, the polarization characteristics of the antennas, and the polarization of the emission of the radio source, differing from random polarization in the general case. For this we represent the connection between the x and y components of plane waves incident on antennas 1 and 2 (E?), E~)) and the x and y components of the field in the focal plane of the antenna (Ex, Ey) in the form [7]