Millimeter wave antenna array with circular polarization

Loop radiation elements with circular polarization radiation pattern are investigated. The research includes, also, two-dimensional array with loop elements and feeding network on the same dielectric substrate. Simulation for substrate ε_R =1 gives appropriate radiation pattern and axial ratio (AR). Simulation for substrate ε_R =2.17 and h= λ_g/40 gives large deformations of radiation pattern and AR. The reason is surface waves. The surface waves are suppressed perforating the substrate with holes. Radiation array 8×8=64 is realized in the frequency range around 60 GHz.