A microwave polarimeter is described which enables the determination of rotation of the plane of polarization of microwaves in the 3.2-cm band. The transmitter-analyzer utilizes klystron tube 723 A/B. The microwaves are fed into a horn which acts as a polarizing agent. The analyzer-receiver consists of a horn antenna, rotatable wave guide, a crystal detector, and an indicator. The microwaves are rectified by a crystal rectifier, and are either detected by a microammeter, a galvanometer, or by an amplifier of appropriate design. Changes of angles of rotation can be detected if they are not less than 2° to 3°.