Dielectric resonator device

Abstract: A dielectric resonator device comprising a resonator body (1) having a dielectric resonator element (2) of dielectric ceramics, and a supporting member (3) integrally formed with the resonator element and made of the same material as that of the resonator element, the resonator element being provided with an inner hole (7), if necessary.

Description: The present invention relates to a dielectric resonator device which may be used as a filter or an oscillator in microfrequency regions. There is a known dielectric resonator device in which a dielectric resonator element is mounted on an inner base wall of a shield casing via a supporting member. FR-A-2496995 describes such a dielectric resonator device comprising a dielectric resonator element which is fixed to a separate insulating support member of different material, and which in turn is mounted on the base of a metal casing. The support member comprises a thin walled hollow cylinder and the dielectric element is provided with a hole extending therethrough to accommodate a threaded metallic rod to adjust the resonance frequency of the resonator element. Another example of such a dielectric resonator device is illustrated in Fig. 1. As will be seen in Fig. 1, it comprises a dielectric resonator element A of a circular or rectangular shape in cross section, a metal casing B for containing the resonator element A and an insulating holder member C made of alumina or forsterite. The resonator element A is mounted on the base portion of the metal casing B by the insulating holder member C so that the resonator element A has a desired Q-characteristic. The resonator element A is connected with the insulating holder member C by means of a heat-resisting adhesive layer D of an adhesive containing a glass glaze as a main component, silica containing adhesive or the other adhesive. When the resonator device is operated, the resonator element A is self-heated with the resonance thereof. In particular, when the resonator is actuated with higher power, the higher the operation frequency is the larger the heat release value in the resonator element. The heat-resisting adhesive layer D has a poor heat transfer efficiency because it contains air bubbles. Therefore, the heat-resisting adhesive layer D makes it difficult to transfer the heat in the resonator element to the insulating holder member C. There may occur a heat-accumulation in the resonator element A so that it has a higher temperature. As a result, there may occur a pull-up between the resonator element A and the insulating holder member C or between the metal casing B and the insulating holder member C, and the resonance characteristic of the device may be varied. Further, since the insulating holder member C is provided for mounting the resonator element A on the base portion of the metal casing B, the number of parts is increased and it is necessary to connect the resonator element A with the insulating holder member C, which results in expensive device. Japanese patent Kokai no. 56-165402 describes a dielectric resonator in which one or more projections are integrally formed with the dielectric resonator element to mount the resonator element to the interior of a casing. In one embodiment, a recess is provided in the upper portion of the resonator element to broaden the frequency range of the harmful resonance mode. According to the present invention there is provided a dielectric resonator device comprising a dielectric resonator body consisting of a resonator portion and a supporting portion integrally formed with said resonator portion, and a base member for mounting said dielectric resonator body, said resonator portion being fixed on the base member by said supporting portion, characterized in that the resonator portion and supporting portion of said dielectric resonator body are integrally formed by pressing as a unitary one-piece body of a same dielectric material, and in that said dielectric resonator body is provided with an inner hole extending through the resonator portion and supporting portion. The inner hole may be intended for expediting a heat dissipation or additionally for tuning the resonant frequency by inserting a tuning member of dielectric material thereinto. The resonator portion and supporting portion of the dielectric resonator body may be provided with a through hold extending along the centre axis thereof. Alternatively, the resonator portion and supporting portion of the dielectric resonator body may be provided with a bottomed hole extending along the centre axis thereof. In this case, the resonator body may be fixed on the base member by clamping a screw through the bottom of the hole. The resonator portion and supporting portion of the dielectric resonator body may be of circular or rectangular cross section. Furthermore, the mounting member may be a portion of a casing for containing the resonator body. Since the resonator portion and supporting portion of the dielectric resonator body are integrally formed and thus there is no adhesive layer therebetween, even if the resonator portion generates a heat as the result of a resonance, the generated heat may be quickly transferred to supporting portion. By provision of the inner bore on the resonator portion, the heat transfer or dissipation may be more effectively expedited. The present invention will now be described by way of example with reference to the accompanying drawings: BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a side view schematically showing a conventional dielectric resonator device, parts being broken away; Fig. 2 is a partially cutaway side view schematically showing a dielectric resonator device according to one embodiment of the present invention; Figs. 3 and 4 are longitudinal sections showing various dielectric resonator bodies in different embodiments of the present invention, respectively. DETAILED DESCRIPTION Referring to Fig. 2, there is shown a dielectric resonator device according to an embodiment of the present invention. The reference numeral 1 represents a dielectric resonator body which may be of dielectric ceramic material such as TiO₂, BaO-TiO₂ . This dielectric resonator body 1 comprises a resonator portion 2 having a circular cross section of a larger diameter and a supporting portion 3 having a circular cross section of a smaller diameter which are integrally formed by means of press molding or other suitable method. The reference numeral 4 represents a metal casing on the bottom wall 5 of which the dielectric resonator body 1 is fixed by an adhesive layer 6. The reference numeral 7 represents a through hole which is provided along the center axis of the resonator portion 2 and the supporting portion 3 of the dielectric resonator body 1. The through hole 7 is intended to increase the contact area between the resonator body 1 and the atomosphere thereby expediting a heat dissipation. When the resonator body 1 is activated, the heat generated in the resonator portion 2 can be quickly transferred to the supporting portion 3 and can be expedited so that the resonator portion 2 can be prevented from raising in the temperature. Fig. 3 shows a further embodiment of the present invention in which there is provided a through hole 9 along the center axis of the resonator body 1. In this case, the through hole 9 comprises a hole portion 10 having a larger diameter in the resonator element 2 and a hole portion 11 having a smaller diameter in the supporting portion 3, and the hole portions 10 and 11 are communicated to each other via a shoulder or frustum portion 12. With the illustrated embodiments, although the resonator element 2 and the supporting portion 3 of the dielectric resonator body 1 are of a circular cross section, it is appreciated that the resonator element 2 and the supporting portion 3 may be formed to have a rectangular cross section or a polygonal cross section. In the embodiment shown in Fig. 4 a bottomed hole 13 is provided along the center axis of the resonator body 1. The bottomed hole 13 has a bottom portion 14 through which a threaded hole 15 is formed. In this case, the resonator body 1 is mounted on the bottom wall 5 of the metal casing 4 by screwing a screw 16 through the threaded hole 15 of the bottom portion 14 into the bottom wall 5 of the metal casing 4. Additionally, the hole provided in the dielectric resonator body of each embodiment may be used to tune the resonant frequency to an intended level. That is, the tuning of the resonant frequency may be performed by inserting loosely a tuning rod of dielectric material into the hole and adjusting the position or level of the inserted tuning rod in the hole (as illustrated by a dot-dash line in Fig. 2). Finally, the dielectric resonator body in the illustrated embodiments may be applied to a stripline arrangement. In this case, a dielectric substrate may be used as the base member, on the upper surface of which the resonator arrangement may be mounted. As illustrated and described above, according to the present invention since the resonator element and its supporting member are integrally constructed by using suitable dielectric materials, any provision of an adhesive layer between the resonator element and the supporting member can be avoided and a heat dissipation in the resonator body can be substantially improved, thereby preventing the resonator element from getting a high temperature and overcoming any problem of peeling off of the adhesive layer. Also, by provision of the inner hole along the center axis of the resonator body it can be avoided that the heat generated in the resonator element is working inside, and thus the heat dissipation can be more effectively expedited, thereby securing a stabilized resonance characteristic of the resonator device. In case the inner hole is to be used to tune the resonant frequency to the intended level, the dielectric resonator device can be easily and precisely tuned to a desired resonant frequency by adjusting the position or level of the insertion of the tuning member of the dielectric material into the hole. Furthermore, the present invention has an advantage that it is possible to reduce the number of parts necessary for assembling the resonator device and to simplify the manufacture in the point of jointing procedure. This results in a cheaper device.

Claims: A dielectric resonator device comprising a dielectric resonator body (1) consisting of a resonator portion (2) and a supporting portion (3) integrally formed with said resonator portion (2), and a base member (5) for mounting said dielectric resonator body (1), said resonator portion (2) being fixed on the base member (5) by said supporting portion (3), characterized in that the resonator portion (2) and supporting portion (3) of said dielectric resonator body (1) are integrally formed by pressing as a unitary one-piece body of a same dielectric material, and in that said dielectric resonator body (1) is provided with an inner hole (7; 9; 13) extending through the resonator portion (2) and supporting portion (3). A dielectric resonator device as claimed in claim 1, characterized in that said base member (5) is a portion of a metal casing (4) for containing the resonator body (1). A dielectric resonator device as claimed in claim 1, characterized in that said inner hole in the resonator body (1) is a bottomed hole (13) through which a clamping screw (16) is screwed for mounting the resonator body (1) on the base member (5).

Inventors: HATANAKA HIROSHI, NISHIKI MASAHIRO NGK SPARK PLU, OHYA KANJI C O NGK SPARK PLUG, HATANAKA, HIROSHI, NISHIKI, MASAHIRO, NGK SPARK PLUG CO. LTD., OHYA, KANJI, C/O NGK SPARK PLUG CO. LTD.
Applicants: NGK SPARK PLUG CO, NIPPON DENGYO KOSAKU KK, NGK SPARK PLUG CO. LTD., NIHON DENGYO KOSAKU CO. LTD.
Application year: 1990
Main classification: H01P7
IPC codes: H01P7, H01P1