A 150-MHz coherent radar system (ice cap sounding)

A 150-MHz coherent radar has been developed for sounding the Antarctic ice cap. The radar has a peak power of 20 W, but it has a chirp gain of 26 and coherent processing gain from 256 to 64000, depending on control settings and application. A low time-bandwidth product was required for the chirp, to allow operation from the surface of the ice with a minimum range of only 250 m. The system uses 17-MHz bandwidth to achieve about 5-m resolution in ice or about 9 m in air. A pair of SAW (surface acoustic wave) dispersive delay lines provide linear FM pulse expansion and compression. The RF and digital portions of the system are described along with the software. The radar was tested successfully in both surface and airborne modes in West Antarctica during December 1987. >