High Resolution Scattering Centre Distributions at Millimetrewave Frequencies Derived by Broad Band ISAR

An experimental radar operating simultaneously at 35 GHz, 94 GHz and 220 GHz has been developed, which is capable to deliver an instantaneous bandwidth of 4000 MHz at 35 GHz and 94 GHz and 8000 MHz at 220 GHz using an FM-CW waveform. To extract the scattering center distribution for a target, an inverse synthetic aperture approach with radar and target in tower / turntable geometry was used. Data were sampled over a full turn of 360deg. The paper describes the measurement setup and the evaluation algorithm. The necessity for polar reformatting at lower frequencies and the easier requirements at W-band, where polar reformatting is not necessary, is discussed in detail. Typical examples for different targets are presented.