Enhanced Frequency‐Beam Scan by a Metamaterial ULWA With Multiple Lorentz Resonances

ABSTRACT Uniform or quasi‐uniform leaky wave antennas (ULWAs) can realize fast beam scanning in space by varying the operating frequency. This scheme is enabled by the dispersive spectrum of the master waveguide (MWG). The dispersion of the MWG is crucial in determining the antenna's frequency beam scanning rate (FBSR), which is commonly low. To enhance the FBSR of a ULWA, we propose a metamaterial waveguide with double Lorentz resonances. We demonstrate that enhanced spectral dispersion of the MWG is formed between two distinct Lorentz oscillations through a superposition effect. By shifting either of the Lorentz oscillations, we can tune the MWG's spectral dispersion. As a result, the ULWA based on this highly dispersive MWG shows a controllable FBSR. We designed and fabricated a ULWA prototype in experiments. The measured FBSR of the ULWA can reach up to 19.8°/%, which is much higher than any previous designs. The proposed ULWA with enhanced FBSR can be used to promote novel applications, including fast target sensing, tracking, and imaging.