Elevation-dependent motion compensation for frequency-domain bistatic SAR image synthesis

While numerically more efficient, frequency domain SAR image synthesis is less easily adaptable to the irregular real airborne trajectories than time-domain image synthesis. Trajectory nonlinearities have another consequence: The image focusing depends on the terrain elevation, hence motion compensation for irregular trajectories on mountainous areas must take into account terrain elevation data. Bistatic SAR processing is elevation-dependent even if the trajectory are perfectly linear (with the exception of the case where both aircrafts follow the same flight line). Terrain elevation can only be ignored at distance very large with respect to the elevation fluctuations, which is only the case in airborne bistatic SAR imaging when the area flown over is extremely flat. We describe here how the monostatic elevation-dependent motion compensation for omega-k algorithm is adapted to bistatic omega-k synthesis algorithm.