Fast Leaky Wave Antenna with Enhanced Frequency Scanning Rate by Dispersive Metamaterial Waveguide

A fast leaky-wave antenna (FLWA) with improved beamscanning capability is proposed. The FLWA is made by a modified rectangular waveguide utilizing an array of metallic rods to enhance the spectral dispersion. In analysis, both the rectangular waveguide and the metallic rods are regarded as metamaterials with Drude and Lorentz dispersions, respectively. By mixing the Drude and Lorentz dispersions, enhanced spectral dispersion is realized. In simulation, an FLWA is designed by etching periodic radiation slots. The FLWA's frequency scanning rate is tailored by changing the metal rods, and enhanced spectral dispersion is realized below the cut-off frequency of the original hollow waveguide. To feed the FLWA, a gradient guidance structure is designed to realize impedance matching between the FLWA and the standard WR-90 waveguide. In experiments, a prototype isfabricated and measured. The experimental results show that the proposed FLWA has a continuous beam-scanning range from 12°to 72°, in the operating frequency band from 7.15 GHz to 7.85 GHz. With these profiles, the forward beam-scanning rate is 6.42 / °, and an average gain of about 12.5dBi in the whole operation band. The FLWA can be a good candidate for facilitating low-cost radars, including fast tracking, imaging, and communications.