A low-loss, continuously tunable microwave notch filter

Abstract

The development in high-end microwave transceiver systems toward the software defined radio has brought about the need for tunable frontend filters. Although the problem is being tackled by the microwave community, there still appears to be an unmet demand for practical tunable filter technologies. With this motivation, this work presents a tuning method that delivers a resonator Q0of 2000–3621 within a minimum tuning ratio of 1:1.42. A continuously tunable notch filter based on this tuning method is presented. The design is manufactured, measured, and verified. It is shown that the tuning technology compares favorably to other selected technologies.