Circularly Polarized Leaky-Wave Antenna With Natural Curl Property

This letter proposes a novel leaky-wave antenna (LWA) based on low profile substrate integrated waveguide (SIW), which can operate in either left-handed circular-polarization (LHCP) or right-handed circular-polarization (RHCP) mode. Different from other kinds of literature, the proposed SIW LWA is capable of CP state switching without introducing multiple LWA elements, phase-correct couplers or polarization converter, which is a single LWA element with a simple coaxial feeding/matching structure. Specially, the periodic slots on its radiation aperture are Archimedean spiral slots which are curved slots with curl property. These curled slots can excite vortex fields in the waveguide channel of SIW, and the generated vortex field is capable of changing vortex direction by selectively exciting the port of LWA, making the CP features flexible. The final Archimedean spiral slotted SIW LWA realizes LHCP or RHCP (AR < 3 dB) in the wide CP band of 27.7–34.6 GHz (BW = 22%), and the LHCP scanning range is from −51° to −10° while the RHCP beam scans from 10° to 50°.