Design of Dual-Stopband Rectangular Waveguide Slot Array Antennas

A dual-stopband rectangular waveguide slot array antenna is presented in this article. First, a rectangular filtering waveguide with dual stopbands is realized by periodically loading a row of T-type resonators and a row of
$\Pi $
-type resonators on the bottom broad wall of the rectangular waveguide, and its dual-stopband characteristic is verified by analyzing the equivalent circuit and dispersion curve. Second, a dual-stopband rectangular waveguide slot array antenna is obtained by etching radiation slots on the top broad wall of the filtering waveguide. To verify the proposed concept, a dual-stopband rectangular waveguide four-slot array antenna is designed, fabricated, and measured. The measured results are in good agreement with the simulation ones. The results show that, compared with the conventional waveguide slot antenna, the proposed waveguide slot antenna has almost the same radiation performance in the −10-dB impedance bandwidth of 5.51–5.95 GHz and achieves additional suppressions of greater than 24.5 dB in 6.6–7.1 GHz and 34.6 dB in 8.4–9.3 GHz, respectively, without occupying extra space.