A multifrequency adaptive radar for detection and identification of objects: Results on preliminary experiments on aircraft against a sea-clutter background

An experimental model of a simple multifrequency continuous wave (CW) radar system has been developed. Preliminary experiments have been performed in order to illustrate the potential of this radar concept in regard to detection, course ranging, and also identification of low flying aircraft against a sea-clutter background. The radar can be organized so as to measure ocean wave height, wave direction, and wave velocity simultaneously for 15 different ocean wavelengths ranging from 150 m to approximately 6 m. An example of such a directional wave intensity spectrum is given. To illustrate the ranging and the identification potential of the technique in regard to airplanes, two different airplane categories, namely a propeller aircraft (Cessna 172) and a rigid jet aircraft (F-16), were flown through the radar beam. The signatures of these two airplanes are show in two signature domains: spatial distribution of scattering centers and motion pattern. The experimental results confirm theories presented in earlier contributions. It remains to introduce two more domains, namely the space/time coherence properties of the target and its polarization characteristics.