Abstract: The present invention relates to a multi-mode filter comprising a carrier on which is mounted a dielectric resonator having a covering of an electrically conductive material in which there is provided an aperture and a coupling structure for coupling input signals to the dielectric resonator or for extracting filtered output signals from the dielectric resonator. The carrier is provided with an enclosing formation of electrically conductive material, which enclosing formation is electrically coupled to the electrically conductive covering of the dielectric resonator, such that the covering and the enclosing formation together form an electrically conductive enclosure for the dielectric resonator. The enclosure formed from the covering of the dielectric resonator and the enclosing formation increases the isolation of the filter and reduces leakage. The filter of the present invention is particularly suitable for use in cascaded resonator filter arrangements, and in duplex/diplex filters.

Abstract: A dielectric resonator body for a multi-mode cavity filter, the resonator body including: a piece of first dielectric material, with at least one substantially flat face for mounting on a substrate, the piece of first dielectric material having a shape such that it can support at least a first resonant mode and at least one spurious response; and a layer of conductive material at least partially coating the resonator body; wherein the piece of first dielectric material includes at least one region having a different dielectric constant to the first dielectric material, whereby the presence of the region of different dielectric constant alters the frequency separation of the resonant mode and the spurious response.

Abstract: A multi-mode cavity filter having a dielectric resonator body incorporating a piece of dielectric material, the piece of dielectric material having a shape such that it can support at least two substantially degenerate resonant modes; and a coupling structure comprising a plurality of independent coupling elements for coupling signals to the piece of dielectric material.

Abstract: A multi-mode cavity filter, comprising: a dielectric resonator body incorporating a piece of dielectric material, the piece of dielectric material having a shape such that it can support at least a first resonant mode and a second substantially degenerate resonant mode; a conductive layer substantially covering the dielectric resonator body but having one or more apertures therein allowing access to the dielectric resonator body; and a coupling structure arranged in an aperture of the one or more apertures, comprising at least one coupling path for at least one of coupling an input signal to the first and second resonant modes and coupling an output signal from the first and second resonant modes, the coupling path having an open-circuit end located adjacent to an edge of the aperture for controlling a strength of electric field generated by the coupling structure.

Abstract: A cavity filter, including a dielectric resonator structure comprising a piece of dielectric material having a shape such that it can support a first resonant mode and a second resonant mode which is substantially degenerate with the first resonant mode; and a coupling structure for exciting a resonant mode within the piece of dielectric material or extracting energy from a resonant mode within the piece of dielectric material; wherein the coupling structure consists of a single patch element in contact with a surface of the piece of dielectric material, the patch element being arranged to couple directly to said first and second resonant modes simultaneously.

Abstract: The present invention provides a multi-mode cavity filter in which signals are coupled to or from a resonator body, using a coupling path with first and second portions arranged such that current flows in opposite directions and the couplings due to the magnetic fields generated partially cancel one another. In this way, the degree of coupling to any particular mode of the filter can be closely controlled by varying the length and/or orientation of the portions with respect to each other.

Abstract: A multi-mode cavity filter, including a first dielectric resonator body incorporating a piece of dielectric material having a shape to support a first resonant mode and a second substantially degenerate resonant mode and at least a second dielectric resonator body incorporating a piece of dielectric material having a shape to support a first resonant mode; a layer of conductive material in contact with and covering the first the dielectric resonator body and the second dielectric resonator body; a first aperture in the layer covering the first dielectric resonator body and a second aperture in the layer covering the second dielectric resonator body, one connecting path(s) arranged to couple signals via the first aperture from the first dielectric resonator body to the second dielectric resonator body via the second aperture, for the purpose of creating or influencing a location of a zero or null in a filter characteristic.

Abstract: The present invention provides multi-resonator cavity filters in which one or more patch elements are introduced into the coupling apertures between resonators, reducing the strength of the electric field in the aperture gap while maintaining the coupling strength from resonator to resonator. This reduced field strength reduces the sensitivity of the resonators to gap-thickness variations, and allows use of the filter in high-power applications.

Abstract: The present invention provides a multi-mode cavity filter in which signals are coupled to or from a resonator body, using a coupling path with first and second portions arranged such that current flows in opposite directions and the couplings due to the magnetic fields generated partially cancel one another. In this way, the degree of coupling to any particular mode of the filter can be closely controlled by varying the length and/or orientation of the portions with respect to each other.

Abstract: A combined filter and antenna structure comprising a multi-mode cavity filter and an antenna, wherein: the filter comprises: a dielectric body provided with a conductive covering; and an interface arranged to exchange energy between a standing wave in the body and a current conveyed external to the body; and the antenna is arranged to exchange energy between a travelling wave outside the body and a standing wave inside the body and the antenna comprises: a first window provided in the covering.

Abstract: The present invention relates to a multi-mode filter comprising a carrier on which is mounted a dielectric resonator having a covering of an electrically conductive material in which there is provided an aperture and a coupling structure for coupling input signals to the dielectric resonator or for extracting filtered output signals from the dielectric resonator. The carrier is provided with an enclosing formation of electrically conductive material, which enclosing formation is electrically coupled to the electrically conductive covering of the dielectric resonator, such that the covering and the enclosing formation together form an electrically conductive enclosure for the dielectric resonator. The enclosure formed from the covering of the dielectric resonator and the enclosing formation increases the isolation of the filter and reduces leakage. The filter of the present invention is particularly suitable for use in cascaded resonator filter arrangements, and in duplex/diplex filters.

Abstract: A multi-mode cavity filter having a dielectric resonator body incorporating a piece of dielectric material, the piece of dielectric material having a shape such that it can support at least two substantially degenerate resonant modes; and a coupling structure comprising a plurality of independent coupling elements for coupling signals to the piece of dielectric material.

Abstract: A multi-mode cavity filter, comprising a resonator body of dielectric material capable of supporting at least two degenerate electromagnetic standing wave modes and having a face, and a conductive pattern on at least part of the face for coupling a radio frequency signal between the pattern and the resonator body.

Abstract: A dielectric resonator body for a multi-mode cavity filter, the resonator body including: a piece of first dielectric material, with at least one substantially flat face for mounting on a substrate, the piece of first dielectric material having a shape such that it can support at least a first resonant mode and at least one spurious response; and a layer of conductive material at least partially coating the resonator body; wherein the piece of first dielectric material includes at least one region having a different dielectric constant to the first dielectric material, whereby the presence of the region of different dielectric constant alters the frequency separation of the resonant mode and the spurious response.

Abstract: A multi-mode cavity filter, comprising: at least one dielectric resonator body incorporating a piece of dielectric material, the piece of dielectric material having a shape such that it can support at least a first resonant mode and at least a second substantially degenerate resonant mode; and a coupling structure comprising a patterned conductive layer for at least one of coupling signals to the piece of dielectric material and coupling signals from the piece of dielectric material.

Abstract: A cavity filter, including a dielectric resonator structure comprising a piece of dielectric material having a shape such that it can support a first resonant mode and a second resonant mode which is substantially degenerate with the first resonant mode; and a coupling structure for exciting a resonant mode within the piece of dielectric material or extracting energy from a resonant mode within the piece of dielectric material; wherein the coupling structure consists of a single patch element in contact with a surface of the piece of dielectric material, the patch element being arranged to couple directly to said first and second resonant modes simultaneously.

Abstract: A multi-mode cavity filter comprises a dielectric body having at least first and second orthogonal resonant modes; a first coupling element formed on a first face of the dielectric body for coupling energy to at least a first resonant mode; and a second coupling element formed on the first face of the dielectric body for coupling energy from the at least a first resonant mode. The dielectric body is capable of supporting a first coupling path between the first coupling element and the second coupling element via the at least a first resonant mode and a second coupling path between the first coupling element and the second coupling element, the second coupling path being such that at least partial cancellation of at least some coupled energy takes place so as to form a zero in a response of the filter.

Abstract: A multi-mode cavity filter, comprising: at least one dielectric resonator body incorporating a piece of dielectric material, the piece of dielectric material having a shape such that it can support at least a first resonant mode and at least a second substantially degenerate resonant mode; a layer of conductive material in contact with and covering the dielectric resonator body; and a coupling structure comprising at least one electrically conductive coupling path for at least one of inputting signals to the dielectric resonator body and outputting signals from the dielectric resonator body, the at least one electrically conductive coupling path being arranged for at least one of directly coupling signals to the first resonant mode and the second substantially degenerate resonant mode in parallel, and directly coupling signals from the first resonant mode and the second substantially degenerate resonant mode in parallel.

Abstract: A multi-mode cavity filter comprises: a dielectric resonator; a coupling structure for at least one of coupling input signals to the dielectric resonator and extracting filtered output signals from the dielectric resonator; a covering of conductive material around the dielectric resonator and comprising an aperture; and a printed circuit board structure having at least one ground plane layer arranged over said aperture and electrically coupled to the covering of conductive material.

Abstract: A dielectric resonator body for a multi-mode cavity filter, the resonator including: a piece of dielectric material, with at least one substantially flat face for mounting on a substrate layer, the piece of dielectric material having a shape such that it can support at least a first resonant mode and at least one substantially degenerate resonant mode; wherein the shape of the piece of dielectric material is such that the first resonant mode and the at least one substantially degenerate resonant mode are capable of being simultaneously independently excited, and wherein the piece of dielectric material is at least partially covered with a layer of conductive material.