Propagation measurements using synthetic aperture radar techniques

Measured complex impulse responses at 1 GHz in mountainous terrain is processed as data from a synthetic aperture array, thus identifying the power reflected from the terrain at various bearings and distances from the receiver. Thus we assign a reflection coefficient and corresponding intensity to each of the triangular faces in the terrain data base. A 3-D plot of the terrain thus shows a "radio eyes" (bistatic radar) view of the mountainside. The reflection coefficient from each triangular face has also been determined theoretically using the generalized Lambertian rough surface scattering model, and agrees well with the measured data (correlation coefficient 0.88). Using this scattering model, we have estimated the impulse response (multipath delay profile) in mountainous terrain directly from topographical map data. The estimated impulse response agrees well with the measured response, thus establishing confidence in the model. Such estimates can help to select cell site locations and antenna configurations to minimize the delay spread.