Measurement method of axial ratio using only the reflection coefficient of waveguide circular polarizer

A circularly polarized feed circuit in a primary radiator of a reflector antenna is often required to have a low axial ratio. Therefore, it is necessary to accurately evaluate the axial ratio. The left- and right-handed circular polarized components are numerically obtained from the complex coefficients measured for dual linear polarized waves. The transmission phase measurement is difficult to measure accurately, particularly at high frequencies such as Ka band. Authors proposed a method to measure the axial ratio of the circular polarization feeding circuit from the reflection coefficient only, and the proposed method has been validated by the numerical simulation.