High Resolution Tower-Turntable ISAR with the Millimetre Wave Radar COBRA (35 / 94 / 220 GHz)

Abstract:
The development of radar based classification and identification processes demand a detailed knowledge of the scattering centre distribution. Independent on the demand of an operational system the resolution of a basic experimental system should be about one order of magnitude above the necessary requirements to allow a thorough judgement of those. To be able to deliver an ultimate database for forthcoming applications, an experimental radar operating at all relevant millimetre wave frequency bands has been developed, which is capable to deliver an instantaneous bandwidth of up to 8000 MHz. The radar uses an FM-CW waveform and is fully solid state. It relies on the most advanced GaAs HEMT Amplifier technique. The radar is used to extract the scattering centre distribution for targets and their statistical properties. The data were processed by an inverse synthetic aperture algorithm to generate high resolution scattering centre distributions for snapshots over small angular intervals and as accumulated images over the full aspect angle range of 360deg. The time necessary for a full turn is below 3 minutes, so in contrary to similar approaches under use of vector network analyzers a high throughput rate for different targets or target conditions is possible. The paper describes the measurement set-up and the evaluation algorithm. Typical examples for different targets are presented.