Mixed-mode resonator using TE101 cavity mode and TE01d dielectric mode

In this paper a new class of in-line filters with pseudoelliptic responses based on mixed-mode resonators is presented. The mixed-mode resonator consists of a cavity with a suspended high permittivity dielectric puck at its center. Both cavity TE101 mode and dielectric TE01δ mode are exploited. This structure realizes the transverse doublet topology and it is capable of a transmission zero that can be easily positioned in both upper and lower stop-band. Couplings are controlled by both irises width and puck rotation. Mixed-mode resonators can be used as building blocks to obtain higher order filters by cascading them through non-resonating nodes. Such filters are capable of transmission zeros very close to the pass-band, resulting in a very high selectivity. Furthermore the presence of the dielectric puck leads to a very compact structure with a stable behavior in temperature.