Miniaturized Circular Polarized TE $_{10}$-Mode Substrate-Integrated-Waveguide Antenna

We propose a miniaturized circularly polarized (CP) antenna based on a substrate integrated waveguide (SIW) working in the dominant TE₁₀ mode. To reduce the overall size, only 1/8 of the SIW cavity is used as the radiation aperture. The two cavities are orthogonally placed to allow CP operation. Because of the via walls on the SIW, the two cavities can be closely placed, which reduces the overall size as well. The performance of the devices is demonstrated using the simulated and measurement results. The 10-dB impedance bandwidth is 1.63-1.66 GHz, and the 3-dB axial-ratio bandwidth is 1.64-1.65 GHz. The measured peak gain and axial ratio are 0.7 dBi and 2.3 dB at 1.645 GHz, respectively .