Frequency modulated Doppler radar for scatterometry and surface profiling

A Doppler coherent combined scatterometer and ground surface profiler is analyzed. The HF-oscillator transmits a periodic saw-tooth or triangular frequency modulation. The reflected signal from the ground is detected by a homodyne receiver. As a result of the periodic frequency modulation, the IF-spectrum at the mixer output has strong components at harmonics of the modulation frequency, which are split up into Doppler side-bands when the radar is moving. The relative energy content of each tone mainly depends upon the frequency excursion of the frequency modulation and the distance from the reflector. By combining the amplitude information of two different tones, both scatterometry measurements and surface profiling from a moving platform are made possible