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

A novel method for achieving circular polarization (CP), high scanning rate (HSR), and consistent gain in leaky-wave antennas (LWAs) is proposed in this paper. 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 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 con-figurations 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°/%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.