Aperture antenna effects after propagation through strongly disturbed random media

Analytical expressions are derived for the effect of aperture antennas on measurements of signals propagating through a strong ionospheric turbulence. Results are presented for the effect of Gaussian apertures on measurements of received signal power, decorrelation distance (or time), mean time delay and time delay jitter. The geometries considered correspond to the case of a single, one-way propagation path between two aperture antennas located in free space and separated by a turbulent layer, and to the case of a monostatic radar system in which radar and target are on opposite sides of a strong scattering layer. It is shown that in strong turbulence aperture averaging can be a significant factor in reducing the received power by angular scattering loss. The results are applicable to the problem of a large antenna aboard a space based radar or to the case of a ground base defense radar.