Atmospheric anisotropy and its effect on the delay power spectra of tropospheric scatter radio signals

The atmospheric anisotropy and its effect on the delay power spectra of signals received on troposcatter radio links were studied. A simplified model for determining an anisotropy coefficient is suggested. Theoretical and measured anisotropy profiles are utilized in the calculations of the delay power spectra of tropospheric links. The impact of the anisotropy on the troposcatter channel as a communication link is studied. Bello's model for the troposcatter channel is modified to include the effect of the anisotropy on the delay power spectra. Several theoretical anisotropy profiles based on the experimental observations and the corresponding spectra are evaluated. It was found that the anisotropy results in increased multipath spread and mean delay parameters. This has a direct effect on the irreducible bit error rate (BER) due to intermodulation distortion. Calculations indicate that an order of magnitude increase in the BER due to the atmospheric anisotropy could result.