Fully Polarimetric Coherent Radar for Migratory Insect Observation

The entomological radar is an important tool for migration insect observation. The traditional entomological radars are rotation polarization non-coherent radars with low range resolution. This paper introduced a fully polarimetric coherent radar that worked at Ku-band and employed the instantaneous full polarization that was able to instantaneously measure the HH, HV, VH and VV polarization signal of the target. It employed the frequency modulation step frequency waveform configuration, and its synthetic bandwidth was 800MHz. The range resolution of the radar was 0.2m. Based on the single target calibration technique, the radar measured the SM of a metal ball and a tilt metal line for radar polarization calibration. The insect orientation can be extracted from the main eigenvector of the SM based on the scattering matrix (SM)-based insect orientation estimation method. The phase modulation-based insect wing-beat frequency extraction method was applied for wing-beat frequency measurement. The field experiments were conducted, which validated the effectiveness of the polarization calibration and the orientation and wing-beat frequency measurement abilities of the radar.