A 94GHz FMCW instrumentation radar

We report on the use of a versatile 94GHz FMCW instrumentation radar to assess optimum hardware configurations for a variety of co-polar and cross-polar target classification studies. Phase noise and sweep linearity are critical parameters in FMCW radars and optimising them is a key objective of any high performance radar system. We have made a systematic comparison of fundamental sources (bias tuned Gunn, varactor tuned Gunn) and multiplied sources (commercial YIG based sweeper, YIG tuned oscillator, permanent magnet YIG tuned oscillator) to ascertain their relative phase noise contributions and FMCW sweep linearities at 94GHz. The radar will also be used to investigate the effect on target return signal coherence as a function of time for different sources. We present details of the calibration against the radar range equation and the effects of variable sweep bandwidth (and hence range resolution). The radar can also be configured for arbitrary polarisation (V, H, +45, -45, RC, LC) and demonstrates high polarisation isolation (33dB) which is required for the accurate assessment of cross-polar radar cross section (RCS), and we will present preliminary results for standard targets and clutter.