A 225-GHZ POLARIMETRIC RADAR

An incoherent 225-GHz polarimetric radar capable of measuring the Mueller matrix of point and distributed targets is described. The transmitter employs an extended interaction oscillator that transmit 60-W pulses of 50- to 600-ns duration. Incoherent measurements of the Mueller matrix are achieved by transmitting four linearly independent polarizations and measuring the scattered wave using a dual-polarized receiver. A novel calibration technique that requires a single in-scene reflector is presented. Polarimetric measurements are presented of a dihedral corner reflector and foliage which are the first polarimetric measurements reported at this wavelength. The foliage measurements indicate a pronounced sensitivity of the polarimetric data to fine-scale surface structure.