A miniaturized bandpass filter using quadruple folded laminated waveguide cavity resonators in LTCC

A miniaturized bandpass filter with 4
^th
order Chebyshev responses is proposed in this paper. The filter is designed using laminated waveguide cavity resonators on a low temperature co-fired ceramic (LTCC) substrate. Miniaturization is accomplished by folding a square cavity with respect to its three symmetric axes. Besides, useful coupling structure is also proposed. With the proposed coupling structures, the miniaturized quadruple folded cavity resonators can be properly arranged in the filter design to minimize the footprint of the circuit. Compared to a direct coupled laminated waveguide filter with the same order, up to 12.5 times size reduction can be achieved.