A planar antenna having two realizable circular polarizations

This paper proposes a planar antenna having two realizable circular polarizations. The proposed antenna can radiate with either right hand circular polarization (RHCP) or left hand circular polarization (LHCP) by using different feeding ports. The substrate integrated waveguide (SIW) cavity is used in the antenna designs, and a single grounded coplanar waveguide (GCPW) is employed as the feeding element to excite the TE₁₂₀ and TE₂₁₀ modes in the SIW cavity. Four rectangular radiation slots are used as the radiating element in order to radiate the desired high gain and circularly polarized wave. From the simulated and measured results, it is seem that the novel polarization antenna which have two realizable circular polarizations possess the advantages of low profile, simple realization and easy integration with planar circuits.