A Compact CRLH Circularly Polarized Leaky Wave Antenna With High Scanning Rate and Consistent Gain

A novel method for achieving circular polarization, high scanning rate (HSR), and consistent gain in leaky wave antennas (LWAs) is proposed in this article. Benefiting from the gaps and metallized vias, two orthogonal electric fields are excited based on the composite right-/left-handed (CRLH) structure, with a large group delay, enabling a compact circular polarized (CP) LWA with HSR. By adjusting the degree of asymmetry of the unit, a smooth leakage constant and consequently a flat gain across a wide scanning range is obtained. As proof-of-concept demonstrations, two configurations of LWAs are simulated, fabricated, and measured. The first one, with a single via and orthogonal gaps per unit cell, achieves CP beam scanning from −25° to +42° over 11.5–12.28 GHz, yielding an HSR of 10.15°/%bandwidth (BW), with gain variation less than 1 dB from −16° to +42°. The second one with four more vias loaded in each unit can continuously scan the CP beam from −33° to +57° over 11.17–11.66 GHz, with an ultra-HSR of 20.93°/%BW and gain variation within 1 dB from −27° to +36°. Compared to existing CP LWAs, the proposed designs offer significantly higher scanning rates while maintaining stable gain over a wide scanning range, demonstrating superior practical value.