A Circularly Polarized SIW Slot Antenna Based on High-Order Dual-Mode Cavity

In this letter, a novel circularly polarized (CP) slotted substrate integrated waveguide (SIW) cavity antenna using a hybrid TE202 mode (HTM) and the eigen TE202 mode (ETM) is proposed and studied. The antenna is designed for Ku-band satellite wireless link applications. It utilizes two different and orthogonal TE202 modes (ETM and HTM) with slots etched on the surface to form left-hand CP radiation. It is directly fed by a coaxial probe with a low profile. The working mechanism and the design approach are elaborated. The current distribution for the two TE202 high-order modes is analyzed. Shorting pins and slots are applied to generate the required CP radiation. To verify the feasibility, the antenna is simulated and fabricated using the conventional printed circuit board (PCB) process. It has a measured -10 dB impedance bandwidth of 4.2% and a 3 dB axial ratio (AR) bandwidth of 1.6%. The peak gain is over 7 dBic in the operation band. The antenna has a size of 0.92λ0 × 0.90λ0, where λ0 is the free-space wavelength at 12.24 GHz. Good agreement between the simulation and measurement results is observed.