Abstract: A multi-mode cavity filter, including two dielectric resonator bodies, the first incorporating a piece of dielectric material having a shape to support a first resonant mode and a second substantially degenerate resonant mode; the second also including a piece of dielectric material; the piece of dielectric material having a shape to support a first resonant mode; a layer of conductive material in contact with and covering both of the dielectric resonator bodies; an aperture in the layer at the interface of the first and second dielectric resonator bodies, for transferring signals from the second dielectric resonator body to the first, transferring signals from the first dielectric resonator body to the second and/or outputting signals from the first dielectric resonator body, the aperture being arranged for coupling signals to the first and second resonant modes in parallel, and/or coupling signals from the first and second resonant modes in parallel.

Abstract: A multi-mode cavity filter, including at least one dielectric resonator body incorporating a piece of dielectric material having a shape to support first resonant mode and a second substantially degenerate resonant mode; excitation device(s) for at least one of: establishing an electromagnetic field external to, but immediately adjacent to, a face of the dielectric resonator body or for extracting energy from an electromagnetic field located external to, but immediately adjacent to, a face of the dielectric resonator body, a layer of conductive material in contact with and covering the dielectric resonator body on the face of the dielectric resonator body: at least one aperture in the layer of conductive material for inputting signals to the dielectric resonator body and/or outputting signals from the dielectric resonator body, wherein the excitation device is located, in at least two dimensions, at an electrical center of the face of the dielectric resonator body.

Abstract: A cavity filter, including first and second dielectric resonator bodies, each incorporating a piece of dielectric material, each piece of dielectric material shaped to support at least a first resonant mode, at least one excitation device for establishing an electromagnetic field within at least a first dielectric resonator body or extracting energy from an electromagnetic field located within the first dielectric resonator body, a layer of electrically conductive material in contact with and covering a surface of the first and a surface of the second dielectric resonator bodies, an aperture in the layer of electrically conductive material for inputting signals to the second dielectric resonator body and/or outputting signals from the second dielectric resonator body wherein the at least one excitation device is arranged to directly excite the first resonant mode or directly extract energy from the first resonant mode in the second dielectric resonator via the aperture.

Abstract: A multi-mode cavity filter includes 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 phased array of coupling elements for coupling signals to the piece of dielectric material.

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 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: 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: 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: A multi-mode cavity filter, including 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 mechanism including at least one aperture in the layer of conductive material for at least one of inputting signals to the dielectric resonator body and outputting signals from the dielectric resonator body, the at least one aperture 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 cavity filter, including first and second dielectric resonator bodies, each incorporating a piece of dielectric material, each piece of dielectric material shaped to support at least a first resonant mode, at least one excitation device for establishing an electromagnetic field within at least a first dielectric resonator body or extracting energy from an electromagnetic field located within the first dielectric resonator body, a layer of electrically conductive material in contact with and covering a surface of the first and a surface of the second dielectric resonator bodies, an aperture in the layer of electrically conductive material for inputting signals to the second dielectric resonator body and/or outputting signals from the second dielectric resonator body wherein the at least one excitation device is arranged to directly excite the first resonant mode or directly extract energy from the first resonant mode in the second dielectric resonator via the aperture.

Abstract: A multi-mode cavity filter, including two dielectric resonator bodies, the first incorporating a piece of dielectric material having a shape to support a first resonant mode and second substantially degenerate resonant mode; the second also including a piece of dielectric material; the piece of dielectric material having a shape to support a first resonant mode; a layer of conductive material in contact with and covering both of the dielectric resonator bodies; an aperture in the layer at the interface of the first and second dielectric resonator bodies, for transferring signals from the second dielectric resonator body to the first, transferring signals from the first dielectric resonator body to the second and/or outputting signals from the first dielectric resonator body, the aperture being arranged for coupling signals to the first and second resonant modes in parallel, and/or coupling signals from the first and second resonant modes in parallel.

Abstract: A multi-mode filter including a resonator body including a piece of dielectric material, the resonator body being configured to support a first resonant mode and a second resonant mode, the resonator body having a covering of an electrically conductive material, wherein the covering is provided with a coupling aperture arrangement, the coupling aperture arrangement including a first coupling segment and a second coupling segment, wherein the first coupling segment is configured to couple a first magnetic field or a first electric field to the first resonant mode or the second resonant mode within the resonator body and the second coupling segment is configured to couple a second magnetic field or a second electric field to the first resonant mode or the second resonant mode within the resonator body.

Abstract: A multi-mode cavity filter, including first and second dielectric resonator bodies, each incorporating a piece of dielectric material, a first piece shaped to support a first resonant mode and a second resonant mode that is substantially degenerate with the first mode, and the second piece shaped to support a third resonant mode and a fourth resonant mode that is substantially degenerate with the third mode, a layer of electrically conductive material in contact with and covering a surface of the first and a surface of the second dielectric resonator bodies, an aperture in the layer, wherein the aperture includes first and second portions, wherein the first portion transfers signals from the first or second resonant mode to the third or fourth resonant mode and the second portion transfers signals from the first or second resonant mode to the third or fourth resonant mode in parallel.

Abstract: A multi-mode cavity filter, including two dielectric resonator bodies, the first incorporating a piece of dielectric material having a shape to support a first resonant mode and a second substantially degenerate resonant mode; the second also including a piece of dielectric material, the dielectric properties, shape and dimensions of which may differ from those of the first dielectric resonator body; the second piece of dielectric material having a shape to support at least a first resonant mode; a layer of conductive material in contact with and covering both of the dielectric resonator bodies; one aperture in the layer appearing at the interface of the first and second dielectric resonator bodies, for transferring signals, the aperture being arranged for directly coupling signals to the first and second resonant modes in parallel, and directly coupling signals from the first and second resonant modes in parallel.

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 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.