Waveguide slotted array antenna for circularly polarized radiation field

Slotted waveguide array antenna with compound slots is proposed. This configuration is able to radiate a circular polarization with a very low axial ratio. Both left-hand and right-hand circular polarization can be independently obtained and therefore this configuration could be used to realize a polarization agile antenna. An planar array of 18×18 elements with uniform spacing is realized in Ka-band. The grating lobes arising due to large inter element spacing are suppressed by loading the waveguide with dielectric. array antenna demonstrates wideband axial ratio of less than 3 dB over wide angel of coverage.