Backscatter of 16 Mc/s Radio Waves From Land and Sea

Relative backscatter coefficients for 16 Mc/s backscatter from land and sea at elevation angles between 5 and 30° were obtained using a large ground-based sounder at Brisbane. For both land and sea, as the angle of elevation decreases, the backscatter coefficient at first increases smoothly and then decreases suddenly at a certain angle which has been called the knee angle. This angle is about 13° for land, and smaller for sea. For a given angle of elevation above 13°, backscatter from sea is about 10 dB stronger than from land.