EP0678928A2 - A dielectric resonator filter - Google Patents

A dielectric resonator filter Download PDF

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Publication number
EP0678928A2
EP0678928A2 EP95302703A EP95302703A EP0678928A2 EP 0678928 A2 EP0678928 A2 EP 0678928A2 EP 95302703 A EP95302703 A EP 95302703A EP 95302703 A EP95302703 A EP 95302703A EP 0678928 A2 EP0678928 A2 EP 0678928A2
Authority
EP
European Patent Office
Prior art keywords
cavity
dielectric resonator
body member
filter
support members
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP95302703A
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German (de)
English (en)
French (fr)
Other versions
EP0678928A3 (ru
Inventor
John Raymond Parker
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Matra Marconi Space UK Ltd
Original Assignee
Matra Marconi Space UK Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Matra Marconi Space UK Ltd filed Critical Matra Marconi Space UK Ltd
Publication of EP0678928A2 publication Critical patent/EP0678928A2/en
Publication of EP0678928A3 publication Critical patent/EP0678928A3/en
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P7/00—Resonators of the waveguide type
    • H01P7/10—Dielectric resonators

Definitions

  • This invention relates to a dielectric resonator filter having a particular, but not necessarily an exclusive, application in a dielectric demultiplexer for communication satellite payloads.
  • Satellite communication systems are used for a number of different purposes, for example, ground surveillance, and telecommunications.
  • the cost of placing communication satellite payloads into orbit is very high and it is desirable to have compact, reliable and light weight resonator filter structures that are sufficiently rugged and stable to withstand both the high levels of vibration experienced by space hardware during the launch phase of a mission and also long term effects of repeated thermal cycling experienced over the duration of the mission. It is of importance to ensure in communication satellite payloads that a stable performance is maintained over a wide range of temperatures.
  • the main problem encountered in realising practical dielectric resonator filters is in supporting the dielectric resonator in a spatial central position within the cavity of the filter.
  • the dielectric resonator should hang in free space but, in practice, it is necessary to provide a support structure for the resonator within the cavity.
  • the support structures of known dielectric resonator filters degrade the unloaded electrical quality factor of the resonator. This is due to additional losses induced in the fabric of the support structure.
  • the resonator support structures used in dielectric resonator filters for communications satellite payloads must, as stated above, be sufficiently rugged and stable to withstand both the high levels of vibration experienced by space hardware during the launch phase of a mission and also the long term effects of repeated thermal cycling experienced over the duration of the mission.
  • the dimensions of the two parts of the cavity are, therefore, critical and must be set at exactly the correct values otherwise the resulting clamping pressure could cause stressing of the support structure and thereby risk damage to the resonator structure.
  • the nature of this cavity structure is such that the cavity dimensions cannot readily be trimmed to effect a change in the clamping pressure.
  • the cavity structure may have to be scrapped. The result of this is that adhesives may be the only effective means of securing the resonator structure in the cavity of this prior art resonator.
  • the thermally induced stress is minimised by closely matching the thermal expansion coefficients of all of the materials from which the filter and support structure are fabricated.
  • the low electrical loss is due to low loss tangents, low dielectric filling factors and the positioning of the support member within the cavity of the resonator so as to avoid areas of high electric field concentration.
  • the invention provides a dielectric resonator filter including at least one microwave resonator having a body member with a cylindrical conductive cavity of uniform diameter formed therein, symmetrically disposed about a longitudinal axis; and a cylindrical dielectric resonator supported in the cavity and having the longitudinal axis thereof coaxial with the longitudinal axis of the cavity characterised in that, the filter further includes an inwardly projecting flange formed integrally with a side wall of the cavity, the location of the flange being off-set relative to the longitudinal centre of the cavity whereby the cavity sections on each side of the flange are of unequal length; two cylindrical support members for supporting the dielectric resonator within the longer section of the cavity, the support members being of a dielectric material and located one on each side of the dielectric resonator; and securing means for securing the two support members, with the dielectric resonator therebetween, within the larger section of the cavity, at least part of the securing means being located within the cavity in an abutting relationship
  • each of the support members is in the form of an annular disc having a cylindrical recess formed in a surface thereof into which a respective one of the ends of the dielectric resonator is located.
  • the body member of the filter is preferably, but not necessarily, of a thermal conductivity higher than that of the dielectric resonator.
  • the securing means include an annular disc located within the longer section of the cavity in an abutting relationship with the said one of the support members, the surface of the annular disc remote from the said one of the support members being securely connected, at four equi-spaced positions around the periphery thereof, to the wall of the cavity.
  • the annular disc is preferably of a silver plated material, for example, brass, aluminium, steel, or a nickel-iron alloy, which is securely connected to the cavity wall, at each of the four positions, by either soldering or brazing.
  • the soldered, or brazed, connections cover an arc of not less than two millimetres.
  • a dielectric resonator filter wherein the securing means of the filter include a clamping member comprising a tubular body member located within the longer section of the cavity, at one end of the body member, the outer peripheral surface of the tubular body member being a sliding fit in the cavity, the tubular body member having an integral flange at one end thereof, wherein the flange member is in an abutting relationship with the body member of the filter, at the said one end thereof, and wherein the length of the tubular body member, between the flange member and the other end thereof, is such that the two support members, with the dielectric resonator therebetween, are securely clamped in an abutting relationship with the said surface of the inwardly projecting flange of the cavity, by the said other end of the tubular body member.
  • the filter includes means for temporarily securing the flange member in an abutting relationship with the body member.
  • the filter includes means secured within the cavity, at the other end thereof, to provide a symmetrical structure.
  • the means for providing a symmetrical structure include a tubular member located within the shorter section of the cavity, at the other end of the body member, the outer peripheral surface of the tubular member being a sliding fit in the cavity, the tubular member having an integral flange member at one end thereof, wherein the flange member is in an abutting relationship with the body member of the filter, at the said other end thereof, and wherein the length of the tubular member, between the flange member and the other end thereof, is less than the length of the cavity between the said other end thereof and the inwardly projecting flange of the body member.
  • the cylindrical support members are of quartz
  • the dielectric resonator is of barium magnesium tantalate
  • the body member is of a silver plated material, for example, silver plated titanium, a nickel-iron alloy or beryllium.
  • the invention also provides a method of assembly for a dielectric resonator according to the present invention including the steps of supporting the body member, with the longer section of the cavity uppermost and the longitudinal axis thereof substantially vertical; inserting one of the support members into the cavity of the body member, with the recessed surface thereof uppermost, whereby it is supported by the inwardly projecting flange; inserting one end of the dielectric resonator into the recess of the said one of the support members; inserting the other one of the support members into the cavity of the body member, with the recessed surface thereof lowermost, whereby the other end of the dielectric resonator is located in the recess of the said other one of the support members; tinning one side of the annular disc of the securing means, at four equi-spaced positions around the periphery of the disc; inserting the tinned disc into the cavity of the body member, with the tinned side uppermost, whereby the disc is supported by the said other one of the support members; clamping the
  • the clamping of the assembled components is effected by means of a clamping plate situated on top of the tinned annular disc, the pressure is applied to the assembled components by a clamping screw connected to the clamping plate, the clamping screw generates a torque of 0.1nM, and the heating of the assembled components is effected at a temperature of 90 degrees centigrade for a period of two minutes.
  • the dielectric resonator filters according to the present invention have a particular, but not necessarily and exclusive application, in the dielectric resonator demultiplexer covered by our co-pending UK Patent Application Number 9400698.8 in that the compact, rugged and stable structure of the filters facilitate vertical mounting of cascaded filter arrangements thereby minimising the 'footprint' of the demultiplexer, i.e. the space occupied by the demultiplexer.
  • one arrangement for a dielectric resonator according to the present invention includes a body member 1 having a cylindrical cavity 2 formed therein and a cylindrical dielectric resonator 3 located within the cavity 2.
  • the dielectric resonator 3 is of a material, for example, barium magnesium tantalate, having a coefficient of thermal expansion to match that of the body member 1.
  • the longitudinal axes of the dielectric resonator 3 is co-axial with the longitudinal axis of the cavity 2.
  • the cavity 2 is of uniform diameter and has an integral inwardly projecting flange 4.
  • the dielectric resonator 3 is supported within the cavity 2 by two cylindrical support members 5, located one on each side of the dielectric resonator 3.
  • the support members 5 are of a dielectric material, for example, a ceramic material, plastic or quartz but are preferably made from quartz.
  • each of the support members 5 is in the form of an annular disc having a cylindrical recess formed in a surface 6 thereof into which a respective one of the ends of the dielectric resonator 3 is located.
  • the resonator assembly comprising the two support members 5, with the dielectric resonator 3 situated therebetween, is securely retained within the cavity 2 by means of the annular disc 7.
  • the resonator assembly is securely clamped between the annular disc 7 which is in an abutting relationship with the adjacent support member 5, and the inwardly projecting flange 4 which is in an abutting relationship with the adjacent support member 5.
  • the assembly is arranged such that the longitudinal centre of the dielectric resonator 3 is in alignment with the longitudinal centre of the cavity 2.
  • the alignment of the longitudinal centres of the cavity 2 and dielectric resonator 3 is effected by the position of the flange 4 in association with the thickness of the supports 5 and the depth of the recesses formed therein.
  • the annular disc 7 is securely connected to the cavity at four equi-spaced positions 8 around the periphery to the wall of the cavity 2.
  • the annular disc 7 is preferably made of a silver plate material, such as brass, or a nickel-iron alloy, and the connection of a silver plated disc 7 to the cavity wall is preferably effected by either brazing, or soldering, i.e. silver soldering.
  • the soldered, or brazed, connections 8 preferably cover an arc of not less than two millimetres.
  • the assembly of the dielectric resonator filter illustrated in Figures 1 and 2 of the drawings is a very delicate operation which must be effected in a clean environment, wearing cotton cloves to avoid contamination of the various component parts during assembly.
  • the assembly is preferably effected using a specially constructed assembly jig.
  • quartz support members 5 are extremely fragile and must, therefore, be well supported during the assembly process and be handled with extreme care, for example, using plastic tweezers.
  • the method of assembly for the dielectric resonator filter of Figures 1 and 2 includes the steps of:
  • the body member 1 of the dielectric resonator filter preferably, but not necessarily, has a thermal conductivity higher than that of the dielectric resonator 3.
  • the heating of the assembled components means that the expansion of the body member 1 will be greater than the expansion of the dielectric resonator 3 and, on cooling, after the annular disc 7 is securely connected in place by the soldering, the support member 5/dielectric resonator 3 assembly is subject to further stressing and is more securely held in position.
  • the resonator assembly is clamped in position by means of a clamping member 9 which, as is diagrammatically illustrated in Figure 5(A) and 5(B) of the drawings, comprising a tubular body member 10 and a flange member 11 located at one end 13 thereof.
  • a clamping member 9 which, as is diagrammatically illustrated in Figure 5(A) and 5(B) of the drawings, comprising a tubular body member 10 and a flange member 11 located at one end 13 thereof.
  • the body member 10 is located within the longer section of the cavity 2.
  • the outer peripheral surface of the body member 2 is a sliding fit in the cavity and the integral flange 11, at the said one end 13 thereof, is in an abutting relationship with the body member 1.
  • the length of the body member 10, between the flange member 11 and the other end 12 thereof, is such that the two support members 5, with the dielectric resonator 3 therebetween, are securely clamped in an abutting relationship with the surface of the inwardly projecting flange 4, by the said other end 12 of the tubular body member 10, when pressure is applied to the end 13 of the clamping member 9 by an adjacent cavity.
  • the clamping member 9 is a silver plated member having an overall length of approximately 3 mm, the internal diameter of the tubular member 10 being approximately 12.5 mm.
  • the resonator assembly is easy to remove, if problems occur, in that there are no soldered joints.
  • the resonant frequency of the cavity 2 can be set by skimming the surface of the clamping member 9, at the end 13 thereof, rather than the cavity itself. This is a cost effective arrangement because of the vast difference in the cost of the clamping member 9 in comparison to the vastly more expensive body member 1.
  • the dielectric resonator filter may include means (not illustrated) for temporarily securing the flange member 11 in an abutting relationship with the body member 1. This could be effected by a suitable adhesive.
  • dielectric resonator filter may include means, secured within the shorter section of the cavity 2, to provide a symmetrical structure.
  • the means for providing a symmetrical structure include a tubular member 23 located within the shorter section of the cavity 2.
  • the outer peripheral surface of the tubular member 23 is a sliding fit in the cavity 2.
  • the tubular member 23 has an integral flange, at one end thereof, in an abutting relationship with the body member 1.
  • the length of the tubular member 23, between the flange member and the other end thereof, is less than the length of the shorter section of the cavity 2 and does not, therefore, affect the clamping action of the filter arrangement.
  • the dielectric resonator filter according to the present invention also includes, as is diagrammatically illustrated in Figures 1 to 4 of the accompanying drawings, coupling screw holes which extend into the cavity 2 on radial planes 14 and 15, that are at 45° to the two orthogonal dual mode electrical field orientations of the cavity 2 i.e. in substantial alignment with the solder fillets 8.
  • the filter will also include two resonance tuning screws, each one of which will extend into the cavity 2 on a radial plane, i.e. the planes 16 and 17, and the plane indicated by the line X-X, that are coincident with a respective one of the two orthogonal mode electrical field orientations of the filter.
  • Screw-threaded holes would be provided in the body member 1 for the coupling and tuning screws to enable the position of the screws to be adjusted, i.e. the extent to which the screws extend into the cavity 2 is adjustable. As, and when, a desired position is reached the screws are respectively locked in position by locking nuts (not illustrated).
  • a coaxial input connector for the cavity 2 would also be provided and would be connected to the boss 18 of the body member 1.
  • the probe of the input connector would enter the cavity 2 through the hole 20 in the boss 18.
  • the dielectric resonator filter includes a plurality of the dielectric resonators, illustrated in Figures 1 to 4 of the drawings, connected in cascade with resonant energy coupling means interposed between each pair of adjacent dielectric resonators.
  • the body member 1 is provided with flanges 21 to facilitate the cascaded couplings.
  • the flanges 21 are each provided with a hole 22 to facilitate the bolting together of the cascaded resonators.
  • the resonant energy coupling means referred to above which, in practice, is in the form of a planar member with a coupling iris formed therein, for example, a cruciform shaped aperture, would be interposed between the flanges 21, and provided with a number of through holes in alignment with the holes 22.
  • a dielectric resonator filter including a plurality of cascaded dielectric resonators of the type outlined in the preceding paragraphs with reference to the accompanying drawings, is ideally suited for use as a multiplexer and/or a demultiplexer.

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EP95302703A 1994-04-22 1995-04-21 A dielectric resonator filter Withdrawn EP0678928A2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9407986A GB2288917A (en) 1994-04-22 1994-04-22 Dielectric resonator filter
GB9407986 1994-04-22

Publications (2)

Publication Number Publication Date
EP0678928A2 true EP0678928A2 (en) 1995-10-25
EP0678928A3 EP0678928A3 (ru) 1995-12-06

Family

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Application Number Title Priority Date Filing Date
EP95302703A Withdrawn EP0678928A2 (en) 1994-04-22 1995-04-21 A dielectric resonator filter

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EP (1) EP0678928A2 (ru)
CA (1) CA2147310A1 (ru)
GB (1) GB2288917A (ru)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2124183A1 (es) * 1996-12-20 1999-01-16 Alsthom Cge Alcatel Filtro de microondas con resonador dielectrico

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0104735A2 (en) * 1982-09-27 1984-04-04 Space Systems / Loral, Inc. Electromagnetic filter with multiple resonant cavities
US4667172A (en) * 1986-04-07 1987-05-19 Motorola, Inc. Ceramic transmitter combiner with variable electrical length tuning stub and coupling loop interface
US4706052A (en) * 1984-12-10 1987-11-10 Murata Manufacturing Co., Ltd. Dielectric resonator
EP0351840A2 (en) * 1988-07-21 1990-01-24 CSELT Centro Studi e Laboratori Telecomunicazioni S.p.A. Dielectric-loaded cavity resonator
EP0352628A2 (en) * 1988-07-23 1990-01-31 Murata Manufacturing Co., Ltd. Dielectric resonator and manufacturing method therefor
EP0392417A1 (fr) * 1989-04-13 1990-10-17 Alcatel Espace Filtre à résonateur diélectrique

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3327257A (en) * 1965-02-05 1967-06-20 Weiss Harry Max Electromagnetic wave permeable window including center conductor therefor
DE8510588U1 (de) * 1985-04-11 1988-02-11 Richard Hirschmann Radiotechnisches Werk, 7300 Esslingen Hohlleiterfilter

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0104735A2 (en) * 1982-09-27 1984-04-04 Space Systems / Loral, Inc. Electromagnetic filter with multiple resonant cavities
US4706052A (en) * 1984-12-10 1987-11-10 Murata Manufacturing Co., Ltd. Dielectric resonator
US4667172A (en) * 1986-04-07 1987-05-19 Motorola, Inc. Ceramic transmitter combiner with variable electrical length tuning stub and coupling loop interface
EP0351840A2 (en) * 1988-07-21 1990-01-24 CSELT Centro Studi e Laboratori Telecomunicazioni S.p.A. Dielectric-loaded cavity resonator
EP0352628A2 (en) * 1988-07-23 1990-01-31 Murata Manufacturing Co., Ltd. Dielectric resonator and manufacturing method therefor
EP0392417A1 (fr) * 1989-04-13 1990-10-17 Alcatel Espace Filtre à résonateur diélectrique

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
6ES JOURNÉES NATIONALES MICROONDES, 21 June 1989 - 23 June 1989 MONTPELLIER, pages 329-330, XP 000170339 M. LABEYRIE 'Nouveaux materiaux pour résonateurs dielectriques' *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2124183A1 (es) * 1996-12-20 1999-01-16 Alsthom Cge Alcatel Filtro de microondas con resonador dielectrico

Also Published As

Publication number Publication date
CA2147310A1 (en) 1995-10-23
GB2288917A (en) 1995-11-01
EP0678928A3 (ru) 1995-12-06
GB9407986D0 (en) 1994-06-15

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