It is well known that material/target properties have an influence on the polarization of the reflected waves. Thus, polarimetric radars can be used to characterize or distinguish targets. Our radar features a modified antenna front-end with circular polarization and 3-dB opening angle of 24°.
The transmit antenna uses left-hand circular polarization (LHCP), while the receive antennas use left- and right-hand circular polarizations (RHCP) respectively.Both channels are demodulated by I/Q mixers, resulting in the four analog channels: I1, Q1, I2, Q2. Polarimetric experiments with radar burst measurements and 100 shots were performed on different soils: Iron sheets, gravel sand with 16mm and 2mm pebble size and fine sand. It was found that evaluating the ratio of the two back scatter levels is sufficient to discriminate the investigated soil types.The first parameter is
c1 = 10 log10(SRR/SLR).
The “Co-pol phase difference” is known to correlate with type, size and spacing of vegetation. It is defined as the average difference between the phase angles in the RR and LL channels. Since the radar is using only one transmitpolarization, only a “cross-polphasedifference”, i.e. the phase difference between RR and RL channels, can be calculated
c2 = φ(XR(Ω)) – φ(XL(Ω)).
Chipset from Infineon.
See Application Note: LR_HZ_APN5_Radar_Polarimetric_ 2016_E