Circularly Polarized Substrate Integrated Waveguide Leaky-Wave Antenna with High Efficiency and Consistent Gain

This paper presents a compact circularly polarized (CP) substrate-integrated waveguide (SIW) leaky-wave antenna (LWA) with consistent gain and high total efficiency at millimeter-wave frequencies. The proposed antenna consists of two layers. The lower layer is a conventional slotted SIW LWA, while the upper layer is an S-dipole array. The S-dipole layer is introduced to achieve circular polarization and improve the total efficiency of the antenna. Simulated results demonstrate that the proposed antenna operates from 24.5 to 29.5 GHz and exhibits a continuous 32° CP beam scan with a realized gain variation between 13 and 14.2 dBic. Moreover, the axial ratio is maintained below 3 dB throughout the operating frequency band. The average realized gain and total efficiency are about 13.7 dB and 93%, respectively.