Passive bistatic radar for helicopters classification: a feasibility study

The alternative use of the Global Navigation Satellite System (GNSS) has recently initiated a number of studies that aim to exploit this system as an illuminator of opportunity for a passive radar system. In this paper a Passive Bistatic Radar configuration using a GNSS as illuminator in near forward scattering zone for micro-Doppler analysis is proposed. The received signal power is the main issue for this kind of passive radar, however it will be argued in the paper that the forward scattering enhancement can be exploited to cope with this issue. The analysis focusses on the case of helicopters rotor blades where the Doppler shift is very high and a large wavelength is useful in reducing the maximum Doppler shift. The power budget analysis for this kind of configuration and target is presented. The paper demonstrates the possibility of detecting these kind of targets and to measure their micro-Doppler signatures. The theoretical analysis demonstrates the effectiveness of the proposed configuration for micro-Doppler signature analysis.