Design of a vertically stackedwaveguide filter with novel cross coupling structures in LTCC

This paper proposes a new cross coupling structure of a vertically stacked waveguide filter in a multilayer low-temperature co-fire ceramic technology. The filter is excited by open-ended microstrip lines. Adjacent cavities are coupled vertically by narrow slots. Cross coupling for quasi-elliptic response is realized by through vias and short-circuited CPW feed line. From the results, the circuit area of the filter can be reduced to about one single cavity size.