Compact circularly polarized SIW cavity-backed antenna based on slot SRR

A circularly polarized (CP) substrate integrated waveguide (SIW) cavity-backed antenna based on slot split ring resonator is proposed. The circularly polarized wave is generated by a split ring-slot etched in the upper metal layer of SIW cavity resonator. A simple coaxial probe is employed to excite this slot split ring resonator and radiate left-handed circularly polarized (LHCP) wave. The proposed antenna retains the advantages of both conventional planar antennas and metallic cavity backed antennas, including compact sizes of 14×14 mm², light weight, easy low cost fabrication and high gain, low cross polarized level. It is experimentally proved that an impedance bandwidth of 10.5% for the reflection coefficient less than -10 dB, the axial ratio (AR) bandwidth of 2.06% for AR less than 3 dB, and the LHCP gain 5.2 dBi has been obtained.