Circularly Polarized Substrate-Integrated Waveguide Tapered Slot Antenna for Millimeter-Wave Applications

A low-cost wideband circularly polarized (CP) tapered slot antenna based on substrate-integrated waveguide (SIW) is presented for millimeter-wave applications. After using two linearly symmetrical slots on the two sides of the SIW, a bandwidth from 80.1 to 108 GHz for both axial ratio <inline-formula><tex-math notation="LaTeX">$<$ </tex-math></inline-formula> 3 dB and VSWR <inline-formula><tex-math notation="LaTeX">$<$</tex-math> </inline-formula> 2 can be achieved. The measuring results also show that the antenna can generate good endfire radiation patterns and gain around 7.9 dBi over this bandwidth. The mechanism for exciting CP wave of the proposed antenna and the influence of the size of the metalized via holes of SIW are also analyzed. The proposed antenna was fabricated by the standard single-layered printed circuit board (PCB) technology, and the measured results agree reasonably with the simulated ones.