Miniaturized Half-Mode T-Septum SIW Bandpass Filter With an Ultrawide Stopband

In this letter, novel miniaturized bandpass filters with wide stopband performance are proposed on the basis of the half-mode T-septum substrate integrated waveguide (HMTSSIW) resonator. The resonant TE
_n00
and TE
_n0m
modes of the HMTSSIW resonator are analyzed precisely using the Ritz-Galerkin method, and their resonant frequencies can be controlled flexibly by adjusting the sizes of resonator. A three-order HMTSSIW filter is fabricated using MEMS technology on the benzocyclobutene dielectric. Simulated and measured results show the advantages of compact size and wide stopband. Then, an electric coupling structure is introduced, which allows the further suppression of the spurious TE
₃₀₀
mode by the controllable mixed coupling. Finally, a miniaturized HMTSSIW filter with 20-dB suppression beyond 10.37f
₀
is simulated and measured.