Dielectric resonators and circuits made therefrom

• US 20040051602A1
• Filed: 10/10/2002
• Published: 03/18/2004
• Est. Priority Date: 09/17/2002
• Status: Active Grant

• Current Assignee: Cobham Defense Electronic Systems Corporation (Cobham PLC)
• Original Assignee: Cobham Defense Electronic Systems Corporation (Cobham PLC)
• Inventors: Pance, Kristi Dhimiter, Channabasappa, Eswarappa
• Granted Patent: US 7,310,031 B2
• Time in Patent Office: Days
• US Class Current: 333/202
• CPC Class Codes: H01P 1/162 absorbing spurious or unwanted modes of propagation
• CPC Class Codes: H01P 1/207 Hollow waveguide filters H01P1/212, H01P1/213, H01P1/215, H01P1/219 take precedence
• CPC Class Codes: H01P 1/2084 with dielectric resonators
• CPC Class Codes: H01P 7/105 Multimode resonators

Abstract

The invention is a dielectric resonator in the shape of a truncated cone and variations with a longitudinal through hole. The truncated cone shape physically displaces the H₁₁l mode from the TE mode in the longitudinal direction of the cone. Particularly, the TE mode tends to concentrate in the base of the cone while the H₁₁ mode tends to concentrate at the top of the cone. By truncating the cone so as to eliminate the portion of the cone where the H₁₁ mode field exists, yet keep the portion of the cone where the TE mode exists, the H₁₁ mode can be virtually eliminated while having no effect on the magnitude of the TE mode.

Resonators in accordance with the invention may be used to build low-loss compact and/or variable bandwidth filters, oscillators, and other circuits, particularly microwave circuits. The conical resonators are arranged relatively to each other within an enclosure in a very efficient and compact design that enhances coupling and the adjustability between adjacent resonators. A plurality of conical dielectric resonators may be arranged in the enclosure such that the longitudinal orientation of each resonator is inverted relative to its adjacent resonator(s). Alternately, the conical resonators may be arranged in a radial pattern relative to each other.

The invention also comprises a spiral coupling loop that provides greater magnetic flux in the same physical volume. Further, conical resonators can be positioned relative to microstrips on printed circuit boards and other substrates so as to provide enhanced electromagnetic coupling between the resonator and the microstrip. Particularly, because the TE mode tends to be concentrated in the base portion of the resonator, the resonator can be mounted upside down to the substrate in the vicinity of the microstrip. In this manner, the TE mode field concentration is positioned above and more closely to the microstrip than with cylindrical resonators. Accordingly, the TE mode field can be positioned much closer to the microstrip than previously possible.

Claims

1. A dielectric resonator comprising a body formed of a dielectric material, said body including a longitudinal through hole, said body varying monotonically in cross-sectional area perpendicular to said longitudinal direction as a function of said longitudinal direction.

2. The dielectric resonator of claim 1 wherein said body comprises a cone.

3. The dielectric resonator of claim 2 wherein said body comprises a truncated cone.

4. The dielectric resonator of claim 3 wherein said truncated cone is truncated such that a TE mode field induced in said resonator is concentrated in said cone and a corresponding H₁₁ mode field is concentrated without said cone.

5. The dielectric resonator of claim 1 wherein said dielectric material is barium tatinate.

6. The dielectric resonator of claim 1 wherein said dielectric material has a dielectric constant of greater than about 45.

7. The dielectric resonator of claim 1 wherein said body comprises at least two discontinuous truncated cones.

72. The dielectric resonator circuit of claim 1 further comprising a first set of mounting screws, each having a first end coupled to one of said resonators and a second end coupled to said housing, wherein at least one of said first and second ends is adjustably coupled to one of said resonator and said enclosure, respectively, so that said resonators'"'"' positions can be adjusted relative to each other.

73. The dielectric resonator circuit of claim 72 wherein a longitudinal axis of each of said screws is parallel to a longitudinal axis of the resonator to which it is coupled.

74. The dielectric resonator circuit of claim 73 wherein said longitudinal through holes of said resonators are threaded to mate with threads of said screws, whereby said positions of said resonators can be adjusted longitudinally by relative rotation of said screws and said resonators.

75. The dielectric resonator circuit of claim 72 wherein said enclosure further comprises holes threaded to mate with said screws, whereby said positions of said resonators can be adjusted longitudinally by rotation of said screws relative to said enclosure.

76. The dielectric resonator circuit of claim 75 wherein said holes of said enclosure are through holes such that said second ends of said screws may protrude outwardly from said enclosure.

77. The dielectric resonator circuit of claim 72 wherein said screws are nonconductive.

8. A dielectric resonator comprising a body formed of a dielectric material, wherein said body comprises a first cylinder having a first radius and a second cylinder having a second radius larger than said first radius, said body further including a longitudinal through hole.

9. A dielectric resonator circuit comprising:

a plurality of dielectric resonators, each comprising a body formed of a dielectric material, said body including a longitudinal through hole, said resonator varying monotonically in cross-sectional area perpendicular to said longitudinal direction as a function of said longitudinal direction;

wherein said resonators are positioned relative to each other such that a field generated in each resonator couples to a field of another of said resonators;

wherein each resonator is longitudinally inverted relative to other resonators to which its field couples.

10. The dielectric resonator circuit of claim 9 wherein said fields comprises TE mode fields perpendicular to said longitudinal direction.

11. The dielectric resonator circuit of claim 9 wherein said circuit is a filter.

12. The dielectric resonator circuit of claim 11 wherein said filter is a microwave filter.

13. The dielectric resonator circuit of claim 9 wherein said bodies of said resonators comprise cones.

14. The dielectric resonator circuit of claim 13 wherein said bodies of said resonators comprise truncated cones.

15. The dielectric resonator circuit of claim 14 wherein said truncated cone is truncated such that a TE mode field induced in said resonators in accordance with operation of said circuit exists primarily within said resonators and a corresponding H₁₁ mode field exists primarily without said resonators.

16. The dielectric resonator circuit of claim 9 further comprising:

an enclosure enclosing said plurality of resonators;

an input coupling element for electromagnetically coupling energy into one of said resonators; and

an output coupling element for electromagnetically coupling energy from another one of said resonators.

17. The dielectric resonator circuit of claim 16 wherein said enclosure is formed of a non-conductive material.

18. The dielectric resonator circuit of claim 17 wherein said enclosure is formed of plastic.

19. The dielectric resonator circuit of claim 16 wherein said circuit has no irises.

20. The dielectric resonator circuit of claim 16 wherein said circuit has no coupling screws.

21. The dielectric resonator circuit of claim 16 wherein said resonators are adjustably mounted to said enclosure so that said resonators'"'"' positions relative to each other are adjustable.

22. The dielectric resonator circuit of claim 21 further comprising a first set of mounting screws, each having a first end coupled to one of said resonators and a second end coupled to said housing, wherein at least one of said first and second ends is adjustably coupled to one of said resonator and said enclosure, respectively, so that said resonators'"'"' positions can be adjusted relative to each other.

23. The dielectric resonator circuit of claim 18 wherein a longitudinal axis of each of said screws is parallel to a longitudinal axis of the resonator to which it is coupled.

24. The dielectric resonator circuit of claim 23 wherein said longitudinal through holes of said resonators are threaded to mate with threads of said screws, whereby said positions of said resonators can be adjusted longitudinally by relative rotation of said screws and said resonators.

25. The dielectric resonator circuit of claim 22 wherein said enclosure further comprises holes threaded to mate with said screws, whereby said positions of said resonators can be adjusted longitudinally by rotation of said screws relative to said enclosure.

26. The dielectric resonator circuit of claim 25 wherein said holes of said enclosure are through holes such that said second ends of said screws may protrude outwardly from said enclosure.

27. The dielectric resonator circuit of claim 22 wherein said screws are nonconductive.

28. The dielectric resonator circuit of claim 21 further comprising tuning plates adjustably mounted adjacent said resonators in order to adjust a center frequency of said circuit.

29. The dielectric resonator circuit of claim 28 wherein said tuning plates are mounted parallel to bases of said resonators.

30. The dielectric resonator circuit of claim 29 further comprising a second set of screws, wherein said tuning plates are mounted to said enclosure by said second set of screws, and wherein said enclosure further comprises holes threaded to mate with said screws of said second set of screws, whereby said positions of said tuning plates can be adjusted longitudinally by rotation of said screws of said second set of screws relative to said enclosure.

31. The dielectric resonator circuit of claim 30 wherein said holes of said enclosure for mating with said second set of screws are through holes such that said second ends of said screws of said second set of screws may protrude outwardly from said enclosure.

32. The dielectric resonator circuit of claim 28 wherein said tuning plates are circular and have a radius smaller than a radius of bases of said resonators.

33. The dielectric resonator circuit of claim 32 wherein said tuning plates have a diameter smaller than 150% of a diameter of said longitudinal through hole.

34. The dielectric resonator circuit of claim 33 wherein said tuning plates have a radius of between 130% and 150% of said diameter of said longitudinal through hole.

35. The dielectric resonator circuit of claim 16 wherein said resonators are arranged with their longitudinal axes parallel and not collinear.

36. The dielectric resonator circuit of claim 16 wherein said resonators are arranged in a radial pattern relative to each other.

37. The dielectric resonator circuit of claim 36 wherein said resonators are arranged such that said longitudinal axes of said resonators intersect at a point forming the center of said radial pattern.

38. The dielectric resonator circuit of claim 37 wherein said enclosure is a cylinder.

39. The dielectric resonator circuit of claim 38 wherein said resonators are adjustably mounted to said enclosure so that said resonators'"'"' positions relative to each other are adjustable.

40. The dielectric resonator circuit of claim 39 further comprising a first set of mounting screws, each having a first end coupled to one of said resonators and a second end coupled to said housing, wherein at least one of said first and second ends is adjustably coupled to said resonator or said enclosure, respectively, so that said resonators'"'"' positions can be adjusted relative to each other.

41. The dielectric resonator circuit of claim 40 wherein a longitudinal axis of each of said screws is parallel to a longitudinal axis of the resonator to which it is coupled.

42. The dielectric resonator circuit of claim 41 wherein said longitudinal through holes of said resonators are threaded to mate with threads of said screws, whereby said positions of said resonators can be adjusted longitudinally by relative rotation of said screws and said resonators.

43. The dielectric resonator circuit of claim 40 wherein said enclosure further comprises holes threaded to mate with said screws, whereby said positions of said resonators can be adjusted longitudinally by rotation of said screws relative to said enclosure.

44. The dielectric resonator circuit of claim 43 wherein said holes of said enclosure are through holes such that said second ends of said screws may protrude outwardly from said enclosure.

45. The dielectric resonator circuit of claim 43 wherein said enclosure is an equilateral polygon comprising an outer radial wall and an inner radial wall and further comprising tuning plates adjustably mounted to said enclosure adjacent said resonators in order to adjust a center frequency of said circuit, wherein said tuning plates are mounted parallel to bases of said resonators by a second set of screws, each said screw having a first end coupled to one of said tuning plates and a second end coupled to said enclosure.

46. The dielectric resonator circuit of claim 45 wherein said enclosure is an annulus.

47. The dielectric resonator circuit of claim 45 wherein said holes in said enclosure for mating with said first set of screws are through holes so that said first set of screws may protrude outwardly from said enclosure and are positioned in one of said inner and outer radial walls of said enclosure and wherein said holes in said enclosures for mating with said second set of screws are through holes so that said second set of screws may protrude outwardly from said enclosure and are positioned in the other of said inner and outer radial walls of said enclosure.

48. A system for coupling energy to or from a resonator comprising:

a resonator comprising a body formed of a dielectric material, said body including a longitudinal through hole and varying monotonically in cross-sectional area perpendicular to said longitudinal direction as a function of said longitudinal direction; and

a coupling loop comprising a conductive wire having a first end and a second end, said wire formed as a substantially planar spiral and wherein said first and second ends are coupled to a signal source or signal destination.

49. The system of claim 48 wherein said coupling loop is positioned parallel to a base of said resonator.

52. The system of claim 49 wherein said body is a cone.

50. A system for coupling energy to or from a resonator comprising:

a substrate;

a resonator comprising a body formed of a dielectric material, said body including a longitudinal through hole and a base surface and a top surface parallel to each other and perpendicular to said longitudinal through hole, said body varying in cross-sectional area in a direction perpendicular to said longitudinal through hole with said cross-sectional area decreasing from said base surface toward said top surface, said resonator being mounted to said substrate by said top surface such that said base is above said substrate; and

a microstrip formed on said substrate, said microstrip having a first end coupled to a signal source or signal destination and a second end positioned beneath said base surface of said resonator.

51. The system of claim 50 wherein said second end of said microstrip comprises first and second legs, each forming an arc around said top surface.

53. A dielectric resonator circuit comprising:

a plurality of dielectric resonators, wherein said resonators are positioned relative to each other such that a field generated in each resonator couples to another of said resonators;

an enclosure enclosing said plurality of resonators;

an input coupling element for electromagnetically coupling energy into one of said resonators; and

an output coupling element for electromagnetically coupling energy from another one of said resonators;

wherein said resonators are adjustably mounted to said enclosure so that said resonators'"'"' positions relative to each other are adjustable.

54. The dielectric resonator circuit of claim 53 wherein said dielectric resonators are cylindrical and include a longitudinal through hole.

55. The dielectric resonator circuit of claim 53 further comprising a first set of mounting screws, each having a first end coupled to one of said resonators and a second end coupled to said housing, wherein at least one of said first and second ends is adjustably coupled to said resonator or said enclosure, respectively, so that said resonators'"'"' positions can be adjusted relative to each other.

56. The dielectric resonator circuit of claim 55 wherein a longitudinal axis of each of said screws is parallel to a longitudinal axis of the resonator to which it is coupled.

57. The dielectric resonator circuit of claim 56 wherein said resonators comprise longitudinal through holes and wherein said longitudinal through holes are threaded to mate with threads of said screws, whereby said positions of said resonators can be adjusted longitudinally by relative rotation of said screws and said resonators.

58. The dielectric resonator circuit of claim 55 wherein said enclosure further comprises holes threaded to mate with said screws, whereby said positions of said resonators can be adjusted longitudinally by rotation of said screws relative to said enclosure.

59. The dielectric resonator circuit of claim 58 wherein said holes of said enclosure are through holes such that said second ends of said screws may protrude outwardly from said enclosure.

60. The dielectric resonator circuit of claim 55 wherein said screws are nonconductive.

61. The dielectric resonator circuit of claim 53 further comprising tuning plates adjustably mounted adjacent said resonators in order to adjust a center frequency of said circuit.

62. The dielectric resonator circuit of claim 61 wherein said tuning plates are mounted parallel to bases of said resonators.

63. The dielectric resonator circuit of claim 62 further comprising a second set of screws, wherein said tuning plates are mounted to said enclosure by said second set of screws, and wherein said enclosure further comprises holes threaded to mate with said screws of said second set of screws, whereby said positions of said tuning plates can be adjusted longitudinally by rotation of said screws of said second set of screws relative to said enclosure.

64. The dielectric resonator circuit of claim 63 wherein said holes of said enclosure for mating with said second set of screws are through holes such that said second ends of said screws of said second set of screws may protrude outwardly from said enclosure.

65. A dielectric resonator comprising a body formed of a dielectric material, said body including a longitudinal through hole, said body varying in cross-sectional area perpendicular to said longitudinal direction as a function of said longitudinal direction.

66. A dielectric resonator for sustaining a transverse electric mode field, said resonator comprising a body formed of a dielectric material, said body including a longitudinal through hole perpendicular to said transverse electric mode field, said body varying in cross-sectional area perpendicular to said longitudinal direction as a function of said longitudinal direction.

67. A dielectric resonator circuit for sustaining a transverse electric (TE) mode field, said circuit comprising:

a plurality of dielectric resonators, each comprising a body formed of a dielectric material, said resonator varying in cross-sectional area parallel to said TE mode field as a function of a direction perpendicular to said TE mode field;

wherein said resonators are positioned relative to each other such that a field generated in each resonator couples to a field of another of said resonators;

wherein each resonator is longitudinally inverted relative to other resonators to which its field couples.

68. The dielectric resonator circuit of claim 67 wherein said circuit is a filter.

69. The dielectric resonator circuit of claim 68 wherein said filter is a microwave filter.

70. The dielectric resonator circuit of claim 68 wherein said resonator is truncated such that a TE mode field induced in said resonators in accordance with operation of said circuit exists primarily within said resonators and a corresponding H₁₁ mode field exists primarily without said resonators.

71. The dielectric resonator circuit of claim 67 further comprising:

a non-conductive enclosure enclosing said plurality of resonators;

an input coupling element for electromagnetically coupling energy into one of said resonators; and

an output coupling element for electromagnetically coupling energy from another one of said resonators;

wherein said resonators are adjustably mounted to said enclosure so that said resonators'"'"' positions relative to each other are adjustable.

78. The dielectric resonator circuit of claim 71 further comprising tuning plates adjustably mounted adjacent said resonators in order to adjust a center frequency of said circuit.

79. The dielectric resonator circuit of claim 78 wherein said tuning plates are mounted parallel to bases of said resonators.

80. The dielectric resonator circuit of claim 79 further comprising a second set of screws, wherein said tuning plates are mounted to said enclosure by said second set of screws, and wherein said enclosure further comprises through holes threaded to mate with said screws of said second set of screws such that said second ends of said screws of said second set of screws may protrude outwardly from said enclosure, whereby said positions of said tuning plates can be adjusted longitudinally by rotation of said screws of said second set of screws relative to said enclosure.

81. The dielectric resonator circuit of claim 80 wherein said tuning plates are circular and have a radius smaller than a radius of bases of said resonators.

82. The dielectric resonator circuit of claim 81 wherein said tuning plates have a diameter smaller than 150% of a diameter of said longitudinal through hole.

83. The dielectric resonator circuit of claim 82 wherein said tuning plates have a radius of between 130% and 150% of said diameter of said longitudinal through hole.