A Short Rugged Ferrite Half-Wave Plate for a Single-Sideband Modulator (Correspondence)

One type of microwave phase shifter consists of two quarter-wave plates between which is placed a half-wave plate whose principal axis is rotatable. The phase shift introduced is directly proportional to the angular displacement of the principal axis of the half-wave plate. Continuous rotation of the principal axis causes continuous advancement or retardation of the phase of the signal traversing the phase shifter. This causes a frequency shift of the signal and the device can thus be used as a single-sideband modulator.