Gain of Antennas with Random Surface Deviations
01 October 1968
The gain of shallow paraboloid reflector antennas with random surface deviations has been derived by Ruze. 1,2 The deviation was based on scalar Kirchhoff approximation to the radiation from reflector antennas. The surface deviations were assumed to be gaussian stationary with gaussian correlation functions. On these bases, an approximate solution for the antenna gain was obtained in terms of an infinite series. The series has been evaluated for relatively small rms surface deviations, e, in comparison to the wavelength, X, namely (47re/X)2 ^ 4. Asymptotic limits (as X --ยท 0) for the gain were also given by Ruze 2 based on a similar analysis by Scheffler3. On-axis gain measurements of large reflector antennas as a function of frequency, exhibit the characteristics as predicted theoretically by Ruze. The present work was motivated primarily to determine the gain in the intermediate region between very long and very short wavelengths and to establish a criterion for applicability of the asymptotic limit. Of primary interest was the near axis field distribution in the focal plane of a paraboloid reflector antenna illuminated by an inci1637