Determination of antenna elevation pattern for airborne SAR using the rough target approach

Data from a forested region of northern Ontario are analyzed to yield an estimate of the antenna elevation pattern for the Canada Center for Remote Sensing airborne synthetic aperture radar (SAR). The extended uniform area was imaged as a series of short flight segments in which the antenna depression angle was systematically stepped, keeping all other acquisition parameters of the aircraft and SAR essentially fixed. Subsequent analysis of the real-time imagery was then performed, dividing average image powers for discrete bands of pixels across the swath to yield the relative gain of the antenna corresponding to the antenna angles for the center of these bands. Combining the total set of these measurements generates the entire elevation pattern. Results are given for the C-band, HH-pattern over an angular range of ~50° and dynamic range of over 30 dB