Classifications

• • 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

• the invention relates to a dielectric resonator comprising a dielectric cylindrical resonator disc, a frequency controller comprising an adjustment mechanism and a dielectric cylindrical adjustment disc, one of planar surfaces of the adjustment disc being arranged against one of planar surfaces of the resonator disc so that the adjustment disc is movable by means of the adjustment mechanism in the radial direction with respect to the resonator disc for adjusting the reson ⁇ ance frequency of the resonator, and an electrically conductive casing.
• dielectric resonators have become more and more interesting in high frequency and microwave range resonator structures, as they provide the following advantages over conventional resonator structures: smaller circuit sizes, higher degree of integration, improved performance and lower manufactur- ing costs.
• Any object which has a simple geometric shape, and the material of which exhibits low dielectric losses and a high relative dielectric constant may func ⁇ tion as a dielectric resonator having a high Q value.
• a diele- ctric resonator is usually of cylindrical shape, such as a cylindrical disc.
• dielectric res ⁇ onators The structure and operation of dielectric res ⁇ onators are disclosed e.g. in the following articles: [1] "Ceramic Resonators for Highly Stabile Oscillators", Gundolf Kuchler, Siemens Components XXIV (1989) No. 5, p. 180-183.
• the resonance frequency of the resonator By bringing a metallic or any other conductive surface to the vicinity of the resonator, it is possible to intentionally affect the electric or magnetic field of the resonator, and thus the resonance frequency.
• the distance of a conductive metallic surface from the planar surface of the resonator is adjusted.
• the resonance frequency changes as a non-lin- ear function of the adjusted distance. Due to this non- linearity and the abrupt slope of adjustment, accurate control of the resonance frequency is difficult and demands great precision, particularly at the upper end of the control range.
• an unloaded Q value varies as a function of the distance of the conductive plane.
• the resonance frequency becomes higher, e.g. to the range 1500-2000 MHz or higher, the dimen- sions of the basic elements of the dielectric filter, such as dielectric discs or adjustment mechanisms are reduced.
• adjusting the resonance frequency of a dielectric resonator with this known, though improved solution sets very high demands on the fre- quency control mechanism, which, in turn, increases the material and production costs.
• the mech ⁇ anical movements of the frequency control device must be made vary small, control will be slower.
• the object of the invention is a dielectric resonator providing a higher control accuracy and con ⁇ trol speed.
• a dielectric resonator which is characterized in accordance with the invention in that the frequency controller further comprises a di- electric fine adjustment disc, one planar surface of which is set against the other one of planar surfaces of the adjustment object, so that the fine adjustment disc is movable by a movement of the adjustment mechani ⁇ sm for fine adjustment of the resonance frequency.
• the frequency controller of the resonator of the invention is composed of a pair of joined dielectric adjustment discs, which are arranged in form of a layer structure resting on the resonator disc. The adjustment discs are engaged with each other mechanically so that their radial movement with respect to each other and to the resonator disc provides two adjustment phases during an adjusting movement.
• the smaller, or the thinner disc i.e. the so-called fine adjustment disc is moved radially a prede- termined distance with respect to the larger, or the thinner adjustment disc and the resonator disc, while the adjustment disc remains stationary.
• the thicker adjustment disc also starts to move in acco- rdance with the adjusting movement in a radial direction with respect to the resonator disc.
• a dielectric resonator is provided in which the frequency adjuster has two slopes of adjustment, whereby the adjustment is fast due to the movement of both adjustment discs, and also extremely accurate due to the fine adjustment func ⁇ tion, which is achieved when the thinner adjustment disc is moved alone.
• the accuracy of adjustment may be increased as high as tenfold, so that the requirements on the accuracy of the adjustment mech- anisms do not have to be made stricter when the frequen ⁇ cy increases, or the requirements may be even moderated on the presently used frequencies.
• Figures 1 and 2 show cross-sectional side views of a dielectric resonator in accordance with the inven ⁇ tion in two different adjusting positions
• Figure 3 shows a top view of a dielectric res- onator of Figure 2
• Figure 4 shows a graph illustrating the reson ⁇ ance frequency of the resonator of Figures 1,2 and 3 as a function of distance L,
• Figure 4A shows an enlarged detail of the graph of Figure 4.
• the structure, the operation and the ceramic manufacturing materials of dielectric resonators are disclosed e.g. in the above-mentioned articles [1] , [2] , and [3] , which are incorporated herein by reference. In the following description, only those parts in the stru ⁇ cture of the dielectric resonator which are essential to the invention will be described.
• dielectric resonator body generally refers to any object which has a suit- able geometric shape, and the manufacturing material of which exhibits low dielectric losses and a high relative dielectric constant.
• a dielectric resonator is usually of a cylindrical shape, such as a cylindrical disc.
• the most commonly used material is ceramic material.
• Figures 1, 2, and 3 show a dielectric resonator of the invention, comprising inside a casing 2 made of a conductive material, such as metal, a dielectric, preferably cylindrical resonator body 3, preferably of a ceramic material and placed at a fixed distance from the bottom of the casing 2, on a supporting leg made of an appropriate dielectric or isolating material.
• the casing 2 is connected to the ground potential.
• the electromagnetic fields of the dielectric resonator extend beyond the resonator body, so it may easily be coupled electromagnetically to the rest of the resonator circuit in a variety of ways depending on the application, e.g. by means a microstrip in the vicinity of the resonator, a bent coaxial cable, a normal straight line, etc.
• Figures 1 and 2 show, as an example of a coupling to the resonator by inductive switching loops 7, which provide the input and the out ⁇ put of the resonator.
• the resonator frequency of a dielectric resona- tor is primarily determined by the dimensions of the dielectric resonator body 3. Another factor that has an effect on the resonance frequency is the environment of the resonator.
• a metallic or any other con ⁇ ductive surface, or alternatively another dielectric body, i.e. a so-called adjustment body to the vicinity of the resonator, it is possible to intentionally affect the electric or magnetic field of the resonator, and thus the resonance frequency.
• the dielectric adjustment element used in the adjustment of the resonator of the invention is composed of a pair of joined cylindrical adjusting discs 5 and 6, which rest in form of a layer structure on the top surface of a resonator disc 3 which is larger or thicker than them, the adjusting disc being supported by an external clamping mechanism, which is not shown in the figure.
• This clamping mechanism may be e.g. a spring mechanism of isolation material arranged between the top part of the casing 2 and the adjustment plate 6. More precisely, the larger, or the thicker adjustment disc 5 rests on top of the resonator disc 3 with its bottom planar surface against the top surface of the resonator disc.
• Adjustment discs 5 and 6 are capable of moving radially with respect to each other and the resonator disc 3 along its top surface by means of an external adjustment mechanism, such as a metallic or ceramic control rod 8.
• the control rod 8 is connected mechan- ically with an isolation space 8A solely to an edge of the fine adjustment disc 6.
• the fine adjustment disc 6, in turn, is engaged mechanically to adjustment disc 5, so that during an adjusting movement, the fine adjus ⁇ tment disc 6 is capable of moving a distance 2Y with respect to the adjustment disc 5, whereafter the adjus- tment disc will also move in accordance with the adjust ⁇ ing movement of the control rod.
• the fine adjustment disc 6 is provided with a radial and elongated hole 10, and adjustment disc 5 is provided with a pin-like projection 11 on its top surface.
• adjustment disc 5 is provided with a pin-like projection, which extends to said hole 10 in the fine adjustment disc.
• the dimensioning of the pin ⁇ like projection 11 and the hole 10 is such that the fine adjustment disc is allowed a radial movement of 2Y in distance on top of the adjustment disc 5, before either end of the hole 10 of the fine adjustment disc 6 engages itself to the pin-like projection, and thus transfers the movement of the adjustment rod so that it causes the adjustment disc 5 to move.
• adjustment disc 5 and the fine adjustment disc 6 with respect to each other and the resonator disc 3 thus results in two adjustment phases during an adjusting movement.
• the fine adjustment disc 6 will move the distance 2Y with respect to adjustment disc 5 and the resonator disc 3, while adjustment disc 5 is stationary. Once the fine adjustment disc 6 has moved said distance 2Y, adjustment disc 5 also starts to move in accordance with the adjusting movement.
• a dielectric resonator in which the frequency controller has two slopes of adjustment, whereby the adjustment is fast when both adjustment discs 5 and 6 are moving, and slower when only the fine adjustment disc 6 is moving, yet extremely accurate.
• the graph shown in Figure 4 shows the resonance frequency fs of the resonator of the invention as a function of the movement L of the adjust ⁇ ment plane.
• a curve A depicts the adjust ⁇ ment when both adjustment discs 5 and 6 are moving, whereby the adjustment slope is dfO/dLl, e.g. 6.3 MHz- /0.6 mm.
• fine adjustment is performed solely with a movement of the fine adjustment disc 6, which is achieved e.g.

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• 1994
  • 1994-10-05 FI FI944660A patent/FI97087C/fi active IP Right Grant
• 1995
  • 1995-10-04 EP EP95934142A patent/EP0748525B1/en not_active Expired - Lifetime
  • 1995-10-04 CN CN95191001.9A patent/CN1136863A/zh active Pending
  • 1995-10-04 DE DE69517963T patent/DE69517963T2/de not_active Expired - Fee Related
  • 1995-10-04 AT AT95934142T patent/ATE194731T1/de not_active IP Right Cessation
  • 1995-10-04 JP JP51235396A patent/JP3176928B2/ja not_active Expired - Fee Related
  • 1995-10-04 US US08/640,800 patent/US5677654A/en not_active Expired - Lifetime
  • 1995-10-04 WO PCT/FI1995/000544 patent/WO1996011508A1/en active IP Right Grant
• 1996
  • 1996-06-04 NO NO962310A patent/NO962310D0/no not_active Application Discontinuation

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