Wave-Front Observations at 35 Ghz on a Line-of-Sight, Radio-Wave Propagation Path

摘要

Recent data taken with the 2800 lambda, 8-element receiving array, at 35 GHz, over a 28-km line-of-right path are reported. The basic data consist of amplitude and relative phase, measured separately at each antenna element in a few milliseconds, with a 'scan' of all eight elements repeated each tenth of a second. From these data, the standard deviation of signal amplitude divided by the mean is computed, and sample from a 32-hour run in July are plotted as a function of time of day. Similarly the standard deviation of phase-difference is so plotted. In like fashion the coherence of the wavefront is determined by the data and plotted against time of day, both for the July run and for an earlier April run. The same is done for the phase structure-function. Both the measured phase structure-function and the measured amplitude covariance are compared with theoretical models of atmospheric structure involving a spectral intensity proportional to some power (-11 3, in the case of the Kolmogrov spectrum) of the turbulence wavenumber. The magnitude of the universal turbulence constant, required for consistency with the data is also obtained, and ranges slightly higher than the values observed by others. Finally, a systematic arrangement of significant data covering 67 two-minute samples taken at hourly intervals, from the April and July runs, is included. For each of the 67 samples, four graphs are presented: (a) amplitude vs time for each element, (b) phase-difference vs time for each adjacent element-pair, (c) cross covariance of amplitude vs time lag, and (d) cross covariance of phase difference vs time lag. From these, basic information is made available in quantity. (Author)