Angular scattering law for the Moon at 6-meter wavelength

Abstract

Several authors [Hargreaves, 1959; Daniels, 1961; Winter, 1962; Fung, 1964; Fung and Moore, 1964; Hagfors, 1964] have tried to deduce the magnitude and scale of lunar surface roughness from radar data using various statistical models. Recently, Beckmann [1965a] has refined the theory to include the important effect of shadowing near the limb. The purpose of this note is to present some recent data that lend weight to the substantial correctness of the theory. Short-pulse (l00-μsec) radar echoes were obtained using the NBS-Instituto Geofísico del Peru 50-Mc/s facility near Lima, Peru. Because the Jicamarca 22-acre array is essentially a transit instrument, long echo integration times were not possible. Although there was adequate radar sensitivity to obtain echoes right out to the lunar limb when the whole antenna was utilized, fairly serious problems arose from the huge dynamic range required to record the echo amplitude from the leading edge properly. Accordingly, only half the available antenna area and only two of the four transmitters were used in this experiment. There were two receiving systems with linear detectors, the one set at higher sensitivity for exploring the echo amplitude near the limb. Polarization was circular to avoid problems with Faraday rotation from the F region. By phasing the two halves of the antenna array to point at different points on the east-west track of the moon, the observation period could be extended to permit about 20 db of digital integration. The parameters of the system are given in Table 1.