Active microwaves - band suppression filter and method for its operation with of a crystal with photonic band gap provided in the feedback loop

摘要

An active microwave notch filter is formed by connecting a photonic bandgap crystal (PBC) in a feedback loop around a microwave amplifier. The PBC has an attenuation bandgap which establishes a frequency range of preferential amplification. Frequency selectivity can be achieved by applying signals to the dielectric members which form the PBC to vary their dielectric constants, and thus the bandgap, or by selecting among multiple parallel PBCs. Antennas are provided to transduce the electrical input to the PBC into electromagnetic radiation, and then back to an electrical signal after the radiation has been filtered by the PBC.