Target Simulator to Calibrate Wideband Radar in Measuring the Internal Layers of the Greenland Ice Sheet

We developed a hardware target simulator for measuring the system response and testing of an airborne wideband radar that operates over the frequency range 600-900 MHz to map the near-surface internal layers in glacial ice. It uses optical and microwave delay lines for evaluating and optimizing the performance of the wideband radar in the continental United States without expensive field trips to polar regions and can be used to test the radar without interfering with commercial wireless devices and television stations. The target simulator replicates the feed-through signal between the transmit and receive antenna, as well as reflections from the air-firn interface and the internal layers of the ice sheet, which are spaced about 50 cm apart. This is because the measured radar resolution is about 60 cm in free space and can map layers with about 50-cm resolution in firn. We simulated the internal layers by incorporating a feedback loop with a short delay line. The target simulator is being used for testing and evaluation of the radar in the laboratory and for in-flight testing of the radar.