A Filtering Leaky-Wave Antenna Designed by the Simulation-Assisted Transfer-Matrix Approach

A bandpass-filtering leaky-wave antenna with characteristics of fast scanning and broad stopband is proposed based on waveguide transmission line. Cavities are periodically arranged at the top and bottom waveguide-wall to enhance the frequency dispersion and further enhance the scanning rate and the scanning angle. However, different from the leaky-wave antenna based on slow-wave transmission-line whose eigen mode has low-radiation, the periodic-loaded waveguide transmission line supporting fast wave and its eigen mode has large radiation. Therefore, its frequency dispersion cannot be accurately calculated by the eigen mode solver of simulation software. A simulation-assisted transfer-matrix approach (SATMA) is used to rapidly estimate the frequency dispersion under the radiation boundary and optimize the leaky-wave periodic units. The first Brillouin zone of this one-dimensional periodic structure is 7.9 GHz to 9.0 GHz under no-radiation boundary calculated by eigen mode solver and is 7.9 GHz to 9.2 GHz under radiation boundary calculated by SATMA method. The calculation results prove that frequency dispersion has significant changes due to radiation. After a compromise design between the transition structure and the periodic leakage structure, finally a filtering leaky-wave antenna is realized with a scanning angle of 7o-53o, a passband of 7.9-9 GHz, and a stopband of 9-20 GHz.