Limitations of the Luneburg lens as a calibration target for a dual-antenna radar system

The Luneburg lens, which is commonly used to calibrate radar scatterometers, may not be appropriate for calibration of dual-antenna systems. Theory and results from measurements of the Luneburg lens reradiation pattern indicate that gross errors may be incurred when using the lens to calibrate a dual-antenna system. Measurements of the reradiation pattern indicate that special attention must be paid to the angular separation of the antennas when using the lens to calibrate a dual-antenna radar system. The angular separation of the antennas must be less than the half-power beamwidth of the lens to ensure accurate repeatable measurements. A formula for estimating the half-power beamwidth is given