A Novel Compact Suspended Stripline Resonator

Suspended stripline (SSL) provides a transmission line medium featuring many advantages, but due to the effective permittivity being close to unity, distributed elements are usually bulky. This letter introduces a novel SSL resonator, which is both compact and low loss. For that purpose, cuboid shaped bricks of metal are incorporated into the SSL channel in the vicinity of the open-circuited side of the resonator. Through this capacitive loading, the area occupied by the resonator can be reduced by a factor of about 5, yet maintaining a high quality factor. The feasibility of this new resonator type is demonstrated with an example bandpass filter at 670 MHz center frequency showing both compact size and low insertion loss.