Single‐/dual‐band triple‐mode cavity filters with wide tunable frequency range

Abstract

Two third‐order continuously tunable bandpass filters featuring single‐/dual‐band operations, respectively, are presented in this letter. One requires a set of three metallic posts in a single metallic cavity, while the other needs one more set to achieve the desired dual‐band operation. The length of each post is adjusted through a screw from its top to establish the center frequency of the passband. Moreover, the coupling among these three resonators can be controlled by varying their locations to determine the bandwidth of the passband. At the bottom of the cavity, grooves are created to linearize and extend the frequency tuning range. In addition, compared to traditional coaxial cavity filters, the proposed designs offer the advantages of ease in fabrication and low in weight. A practical example for the dual‐band design is presented for experimental verification. The simulated range for the tunable passband is from 0.8 to 3.2 GHz, which amounts to a fractional bandwidth of 120%. The simulated results agree well with the measured data.

A high‐power dual‐mode oversized substrate‐integrated waveguide (OS‐SIW) filter with flexible transmission zero (TZ) and bandwidth

“…However, this U‐shape slot structure may generate energy leakage and significant insertion loss. Multimode resonators are well‐known for achieving controllable TZs and bandwidth for filter applications 8–15 . Nevertheless, the high‐power requirement is hardly considered in the above structures.…”

“…Multimode resonators are well-known for achieving controllable TZs and bandwidth for filter applications. [8][9][10][11][12][13][14][15] Nevertheless, the high-power requirement is hardly considered in the above structures. Several attempts have been achieved to improve the power capacity.…”