Large Frequency-Ratio Dual-Band Leaky-Wave Antenna With Low-Frequency Polarization Reconfiguration

A dual-band leaky-wave antenna based on dual-mode microstrip transmission lines (MTLs) with a large frequency ratio of 3.4 is presented. By loading the periodic open microstrip branches, the MTL can operate on the quasi-TEM mode in microwave band and quasi-TE_0.5,0 mode in millimeter-wave band, respectively. Rectangular parasitic patches with periodic arrangement are used to generate radiation in the microwave band. Comb slots are loaded on the parasitic patch to reduce the effect of the microwave radiation on millimeter-wave band, and it also excites the TM₀₁ and TM₁₀ modes of the rectangular parasitic patch at 10.3 GHz and 12.2 GHz, respectively, to achieve frequency-controlled polarization reconfigurability. Transverse slots are loaded on the dual-mode MTL to generate radiation in the millimeter-wave band. The fabricated antenna shows polarization reconfigurability in the frequency range of 9 GHz to 13 GHz. And the antenna can achieve a beam steering range of 58° (−40° to 18°) in the 9 GHz to 13 GHz and 38° (–42° to −6°) in the 32.6 GHz to 40 GHz.