A new class of miniaturized dual-mode substrate integrated waveguide (SIW) band-pass filters is proposed, which are loaded by double/single T-shaped structures. By introducing a double T-shaped structure in original dual-mode SIW band-pass filter, the resonant frequency is lowered from 9.46 GHz to 8.91 GHz due to the longer effective length. The introduced single T-shaped structure performs an even lower resonant frequency of 6.88 GHz for the same reason. Compared with dual-mode band-pass filters in references, the proposed dual-mode SIW band-pass filters with double/single T-shaped structures have the advantages such as compact size (like microstrip dual-mode filters) and high Q factors (like SIW dual-mode filters). The proposed filters are fabricated and measured, and the experimental results are in good agreement with simulated ones.
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