Third-Order Frequency-Agile Substrate-Integrated Waveguide Filter With a Pair of Transmission Zeros.

In this letter, we present a third-order frequency-agile substrate-integrated waveguide (SIW) filter with a pair of transmission zeros. In addition, a relationship between the symmetric and asymmetric topologies for having same frequency responses is derived in this letter so that the coupling values of the asymmetric filter topology can be directly obtained from those of the symmetric one. For practical implementation, we also present a new methodology for physical implementation of a source-to-multiresonator coupling for frequency-tunable SIW resonator structure. The filter has been fabricated and measured for verifying the presented filter topology. [ABSTRACT FROM PUBLISHER]