Abstract: A polarizer reflector includes a reflecting layer backing a meander-line polarizer effective to convert the incident beam from linear polarization to circular polarization during the propagation of the beam forwardly through the polarizer, and to reconvert the beam reflected from the reflecting layer from circular polarization to linear polarization but rotated at a predetermined angle, preferably at a right angle, with respect to the polarization of the incident beam. Also described is a reflecting plate-type scanning antenna including a front collimating paraboloid reflector with the above-described polarizer reflector serving as the back reflector, which arrangement has been found to substantially increase the frequency range of the scanning antenna.