Circularly Polarized Patch Array Fed by Slotted Waveguide

A novel circularly polarized patch array fed by a slotted waveguide is proposed. Optimized circular polarization is achieved with a split truncated patch flexibly. Improved bandwidth and efficiency are obtained by utilizing the feeding waveguide. The proposed array can also be viewed as a waveguide-fed slot antenna that is covered with a patch array. Once the element admittance characteristic is determined, it can be conveniently designed just like waveguide-fed slot arrays. Parametric study on a circularly polarized element at 10.5 GHz is conducted to provide an instructive design guideline. Then, a 1 $\,\times\,$ 10 circularly polarized array is developed. Measured impedance bandwidth of 4%, axial-ratio (AR) bandwidth of 3.2%, and a gain of 15.94 dB with aperture efficiency of 62% have been obtained, which demonstrate desirable array performance.