Abstract: A resonator for use in a radio frequency filter including a substantially planar resonant portion that is substantially elliptical in plan. The resonant portion is mounted on a dielectric substrate. The resonator is configured to operate in at least a mode in which resonance occurs with a radial current and with substantially no current along the edge of the resonant portion. A filter comprising a plurality of the resonators is also disclosed.

Abstract: A radio frequency filter for generating at least first and second predetermined radio frequency bands from a received radio frequency signal. The filter includes an input coupled to a first resonant component, such as a planar open square loop resonator, which in turn is operatively coupled to a second resonant component and a third resonant component. The second and third resonant components are operatively coupled to each other and are coupled to first and second outputs of the filter. In one embodiment, the couplings between resonator components take the form of magnetic and/or electrical couplings. The resonator components are made from conductors or in some cases, from superconducting material. The radio frequency filter operates at microwave frequencies between 500 MHz and 20 GHz.

Abstract: A radio frequency filter for generating at least first and second predetermined radio frequency bands from a received radio frequency signal containing signals in at least the first and second radio frequency bands. The RF filter includes a first resonant component for accepting the radio frequency signal via an input coupling, a second resonant component operatively coupled to the first resonant component via a first coupling and third resonant component operatively coupled to the first resonant component via a second coupling and to the second resonant component via a third coupling. A first output is operatively coupled to the second resonant component via a fourth coupling, and a second output is operatively coupled to the third resonant component via a fifth coupling. The characteristics of the couplings and the resonant components are selected such that the first predetermined radio frequency band is available at the first ouptut and the second radio frequency band is available at the second output.

Abstract: A resonator for use in a radio frequency filter including a substantially planar resonant portion that is substantially elliptical in plan. The resonant portion is mounted on a dielectric substrate. The resonator is configured to operate in at least a mode in which resonance occurs with a radial current and with substantially no current along the edge of the resonant portion. A filter comprising a plurality of the resonators is also disclosed.