Miniaturized folded substrate integrated waveguide filters in LTCC

This paper proposes miniaturized band-pass filters with folded substrate integrated waveguide (FSIW) resonators using multilayer low-temperature co-fired ceramic (LTCC) technology. The FSIW resonator is used for the circuit size reduction with its footprint about a half of the conventional TE₁₀₁ mode. With LTCC technology, it is more flexibility to organize the cavities of filters because of the 3-D arrangement. The vertically stacked cavities are coupled by slots, which can implement different coupling signs with different locations. A new useful topology of FSIW filter is then proposed. Two Ku-band three-order band-pass filters with different transfer responses, Chebyshev and elliptic, are given and verified by experiments. A good agreement between the simulated and measured results is observed, which has also validated the proposed concept of design with the FSIW technology.