Wideband multilayer dual circularly-polarised antenna for array application

A wideband multilayer antenna with dual circular polarisations (CPs) is presented. The antenna consists of stacked square patches fed by striplines and a branch line coupler. Two orthogonally positioned H-shaped slots are used as the coupling aperture for the striplines. The dual-CP radiation is obtained by exciting the TM₀₁ and TM₁₀ modes of the radiating element with 90° phase differences. The presented dual-CP antenna has a multilayer configuration with a compact size and it is suitable to be applied to the design of array antennas. To verify this design concept, one prototype operating in the K-band is designed and fabricated. The measurement results show that the prototype has more than 13% impedance bandwidth with good CP radiations.