U-shaped slots for circularly polarized slotted waveguide array

An experiment for a circularly polarized radiator composed of two slots and a U-shaped slot pair is performed. This radiator can be excited by either a traveling or a standing wave. The measured axial ratio is about 1 dB in the main beam direction. A good axial ratio extending over wide angle is realized by controlling the spacing between the two U-shaped slots. The measured values of the radiator for circular polarization agree well with prediction. The full wave analysis is necessary for future practical design.