Dual-mode substrate integrated hexagonal cavity (SIHC) filter with uncoaxial feeding structure

Abstract

Novel uncoaxial dual-mode substrate integrated hexagonal cavity (SIHC) filters are presented for high selectivity application. The SIHC filters with uncoaxial feeding structure can add two extra coupling paths to their topologies: one is a source–load coupling path, and the other is a non-physical higher order modes cross-coupling path. Under the circumstances, the proposed filter can generate up to three transmission zeros (TZs) for improving stopband performance. Meanwhile, the numbers and the locations of TZs can be controlled conveniently by tuning the uncoaxial feeding structure. Accordingly, the filter not only has good selectivity due to flexible TZs, but also has a small size by virtue of its single-cavity structure. Two experimental filters at the same central frequency of 10 GHz but with different fractional bandwidths of 2 and 5% and numbers of TZs from 2 to 3 are designed, fabricated, and measured to validate the proposed structure. The measured results agree well with the simulated ones, with their good performance just as pedicted.

Keywords:

• substrate integrated hexagonal cavity (SIHC)
• filter
• dual-mode
• uncoaxial structure

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by National Natural Science Foundation of China [grant number 61301052], [grant number 61201001], [grant number 51172034].