Reciprocal Quarter‐wave Plates in Circular Waveguides

This chapter describes the principle of one class of reciprocal quarter‐wave plate, which may be used to implement a number of different control devices. An equivalent waveguide model is separately employed to form the effective dielectric constants of the two polarizations from the experimental knowledge of the waveguide and free space wavelengths and the radius of the circular waveguide. If two similar quarter‐wave plates are cascaded, a vertically polarized wave incident on the first plate is converted to a horizontal one at the output plate, i.e. a linearly polarized wave is rotated by twice the angle between the input and the plate orientations. The description of an inhomogenous waveguide partially filled by some dielectric material is often facilitated by forming the equivalent waveguide model consisting of a homogenous waveguide having the same cross‐section but fully filled by an effective relative dielectric constant.