| 摘要 |
An electromagnetic field frequency filter (300) which includes a bus waveguide (304) that carries a signal having a plurality of frequencies, including a desired frequency, and a drop waveguide.(306) A resonator-system (302) is coupled to the bus and drop waveguides via directional couplers (308, 310) and transfers the desired frequency from the bus waveguide (304) to the drop waveguide (306) while allowing transmission of the remaining frequencies in the bus waveguide.(304) The input signal in the bus waveguide (304) is coupled from the bus waveguide (304) to the resonator-system (302) by a first directional coupler.(308) The resonator-system (302) includes two sub-elements (312, 314) each comprising at least one resonator. The first directional coupler (308) splits the input signal into two preferably equal parts and directs each part into a resonator sub-element.(312, 314). The desired frequency is transferred to the drop waveguide (306) by a second directional coupler.(310) The non-desired frequencies are returned to the bus waveguide,(304) in the forward direction, by the directional coupler (308). Preferably, the resonators are formed by periodic dielectric structures with phase shifts.
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