FSIW cavity filter and Derivative FSIW cavity and its filters with LTCC technology
A three order cross-coupling FSIW (Folded Substrate Integrated Waveguide) cavity filter with three TZs (Transmission Zeroes) is proposed firstly. By the merit of the LTCC (Low-Temperature Co-fired Ceramic) technology, the substrate area occupied by the filter is reduced by approximately 50% compared with the traditional SIW filter, and it still exhibits a sharp frequency selection performance. To further reduce the cavity area, a four order rectangular Derivative FSIW cavity filter is designed. Finally, a cylindrical Derivative FSIW cavity is proposed for the first time and a filter is constructed to prove its validity. The two types of Derivative FSIW cavities not only promises to reduce the substrate area, but also have the character of depressing some higher modes, which helps to realize large depression above and below the pass-band.