Planar Dual Circularly Polarized Complementary Antenna for Endfire Radiation

A planar dual circularly polarized (CP) complementary antenna for endfire radiation is proposed. A half-mode substrate integrated waveguide (HMSIW) cavity is designed for vertical polarization and a pair of half wavelength printed electric dipole (E-dipole) is used for horizontal polarization. Then, a 3 dB coupler is introduced to combine above orthogonal polarizations, which realize different sense CP waves by exciting different ports. Also, for improving the front-to-back ratio (FBR) of the proposed antenna, a director formed by series of metal strip is designed. The simulated results show that the proposed antenna can realize left-hand CP (LHCP) and right-hand CP (RHCP) endfire radiation.