Fully Polarimetric Calibration of Ka-Band Radar with Band Separated Twist Reflector

A fully polarimetric calibration method for a partially polarimetric Ka-band radar combined with a frequency selective twist reflector is presented. Such a system enables the capture of the entire scattering matrix by dividing the available bandwidth instead of requiring additional channels. To test this principle, a quasi-monostatic measurement setup is arranged and described in this paper. Various disturbances, among others, occur due to the use of a twist reflector, which must be taken into account and require a novel calibration approach. Therefore, a four step calibration process containing a single 22.5° oriented dihedral reference, electrical length compensation, phase band correction required by the band separation and an application of the monostatic condition is introduced. A selection of corner reflector types is used for a measurement campaign and processed by the proposed signal processing chain. Targets are clearly identified after applying Pauli decomposition to the calibrated measurement data. Eventually, various error effects are analyzed.