An N-band resonator, particularly well-suited for reconfigurability, is presented in this paper together with its synthesis. The resonator is based on the association of an N-band dual-behavior resonator and tunable capacitors. Its topology consists of a parallel association of N + 1 different bandstop structures, each one composed of a stub terminated by a capacitor. N pass bands, separated from each other by a transmission zero, are then obtained. As each bandstop structure independently controls one transmission zero, the use of variable capacitors allows each of them to be tuned independently and then to reconfigure the resonator in terms of transmission zeros and resonant frequencies. After the presentation of the general synthesis, this principle is validated by the realization of a tri-band resonator in microstrip technology.
