Active tunable substrate integrated evanescent-mode cavity resonator using negative resistance

A new active tunable substrate integrated evanescent-mode cavity resonator with gain is presented. Gain is achieved through loading the resonator with a negative resistance circuit. The negative resistance is realized using a single transistor circuit implemented on an extra circuit-board layer and coupled into the resonator using aperture coupling. A co-simulation of the electromagnetic structure and active circuit is used for the design of the active tunable resonator. The frequency tuning range of the resonator is from 2259 MHz to 2963 MHz (1.31:1). The resonator exhibits a gain of around 1 dB and a maximum loaded quality factor of 253.