We present measurements on the polarization response of Ni-NiO-Ni diodes coupled to asymmetric spiral antennas. Our data are for the wavelength dependence of the orientation of the major axis of the polarization ellipse over the wavelength range 10.2-10.7 mum. The data are well fit by a two-wire antenna model. We find that the modes excited on the antenna are a combination of the balanced and unbalanced modes of a two-wire lossy transmission line.