Wave transmission lines and networks – Plural channel systems – Having branched circuits
Reexamination Certificate
2000-11-22
2002-08-13
Pascal, Robert (Department: 2817)
Wave transmission lines and networks
Plural channel systems
Having branched circuits
C333S202000, C333S219100, C333S222000
Reexamination Certificate
active
06433652
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a multimode dielectric resonator apparatus that operates in multiple resonant modes, to a filter and a duplexer that use the resonator, and to a communication apparatus that uses the filter and/or the duplexer.
2. Description of the Related Art
Conventionally, a dielectric resonator having a dielectric core arranged in a cavity uses a mode such as a TE01&dgr; mode or a TM01&dgr; mode. In a configuration of a multistage dielectric resonator apparatus formed using the aforementioned dielectric resonators, a plurality of the dielectric cores are provided in a cavity.
In the aforementioned configuration using the single resonant mode generated in the single dielectric core, however, the overall size increases in proportion to the increase in the number of resonators. In addition, the plurality of dielectric cores must be positioned and fixed with high accuracy. This makes it difficult to manufacture dielectric resonator apparatuses, such as dielectric filters, having consistent characteristics.
The present applicant has submitted Japanese Unexamined Patent Application Publication No. 11-145704, regarding a dielectric resonator apparatus in which, while a single dielectric core is used, the multiplex number is increased. The dielectric resonator apparatus according to the above application is arranged such that, when resonant spaces are represented by x, y, and z rectangular coordinates, TMx, TMy, and TMz modes are generated in which electric-field vectors extend toward the individual x, y, and z axes, and TEx, TEy, and TEz modes are generated in which electric-field vectors form loops in the plane directions perpendicular to the individual x, y, and z axes. At most six modes can thereby be used.
In the multimode dielectric resonator apparatus according to the above-described patent application, to couple predetermined resonant modes to each other, either grooves or an opening are provided in a portion in which electric fields of two modes that will be coupled together are concentrated, perturbations are applied to the electric fields in that portion, and energy is thereby transferred between the two resonant modes. However, when the TM mode and the TE mode are coupled together in the described construction, the two modes interact perpendicular to each other, so secure coupling cannot be easily obtained. The coupling grooves or openings must be deeply formed to obtain secure coupling therebetween. However, since electric-field distributions of the individual resonant modes are thereby diverged, problems are caused in that the resonant frequencies are increased, and in addition, adjustment of the filter characteristics is difficult.
SUMMARY OF THE INVENTION
In view of the above problems, the present invention provides a multimode dielectric resonator apparatus that allows TE modes and TM modes to be securely coupled to each other without increasing the resonant frequencies and that allows the filter characteristics to be easily adjusted.
The invention also provides a filter using the aforementioned multimode dielectric resonator apparatus.
The invention further provides a duplexer that uses the aforementioned multimode dielectric resonator apparatus.
The invention also provides a communication apparatus using the above.
According to one aspect of the present invention, a multimode dielectric resonator apparatus is configured in a dielectric resonator apparatus formed by arranging a dielectric core in a conductive cavity. The dielectric core is configured of a TM-mode dielectric core portion for primarily determining resonant frequencies of TM modes so that at least one of the TM modes resonates in an operating frequency band, and other TM modes resonate at frequencies higher than the operating frequency band; and a TE-mode dielectric core portion for primarily determining resonant frequencies of TE modes so that individual ones of multiple TE modes resonate in the operating frequency band. Either the shapes of the TM-mode dielectric core portion and the TE-mode dielectric core portion, or support structures therefor, are arranged asymmetrically, and predetermined TM modes and TE modes are coupled to each other so that, in areas where electric fields of the predetermined TM-modes are distributed, TE-mode electric fields are generated, having the same directional components as those of the electric fields of the TM modes.
As described above, although neither grooves nor openings are provided for coupling the TM modes and the TE modes, secure coupling can be obtained according to the arrangement in which the TM modes and the TE modes are coupled together without causing their resonant frequencies to increase. In addition, characteristic adjustment can be easily implemented according to the arrangement made such that divergences that can be caused by the coupling grooves or openings in electric-field distributions in the individual modes are reduced; that is, according to the arrangement made such that the coupling structures between the TM modes and the TE modes do not influence other resonant modes, characteristic adjustment can be easily implemented.
In the multimode dielectric resonator apparatus, the TM-mode dielectric core portion is formed to have a plate-like shape, the TE-mode dielectric core portion is formed to have a shape protruding from an upper face and a lower face of the platelike portion. Also, the TM-mode dielectric core portion and the TE-mode dielectric core portion are arranged asymmetrically; that is, there is a difference between the upper-side protruding amount and the lower-side protruding amount. With this construction, the asymmetry can be easily arranged; the TM-mode electric-field distribution areas and TE-mode electric-field distribution areas can be separated to minimize the area in which the TM-mode electric field and the TE-mode electric field overlap; and the design procedure can therefore be simplified.
The protruding parts may have any shape as long as the five modes of interest (TMx, TMy, TMz, TEx, TEy) have substantially the same resonant frequency. For example, in a quintuple mode filter for the 2 GHz band, the respective resonant frequencies should be within about 0.1 MHZ of each other.
According to another aspect of the invention, dielectric members for supporting the TM-mode dielectric core portion and the TE-mode dielectric core portion in the cavity are arranged asymmetrically with respect to the dielectric core. That is, the support structures of the TM-mode dielectric core portion and the TE-mode dielectric core portion have asymmetry. With the asymmetry thus arranged using the support members that support the dielectric core in the cavity, the dielectric core is arranged to be asymmetric, so that the manufacture thereof can be facilitated. In addition, the divergences in the electromagnetic-field distributions in other modes whose resonant frequencies are outside the operating frequency band can be minimized.
According to a further aspect of the invention, in the multimode dielectric resonator apparatus, the TM-mode dielectric core portion and the TE-mode dielectric core portion are independently supported in the cavity, either the position of one of the dielectric core portions or the positions of both dielectric core portions can be fixed, and the TM-mode dielectric core portion and the TE-mode dielectric core portion are thereby arranged to have the asymmetry. According to this construction, the relative positional relationship between the TM-mode dielectric core portion and the TE-mode dielectric core portion and the positions thereof in the cavity can be determined after the apparatus is assembled. Alternatively, the intensity of coupling between the TM modes and the TE modes can be determined in a wide range at the time of assembly of the multimode dielectric resonator apparatus; and the coupling adjustment therefor can be implemented.
In other aspects of the invention, by coupling TM modes and TE modes according to other forms of asymmetry, indir
Abe Shin
Hattori Jun
Ise Tomoyuki
Wakamatsu Hiroki
Murata Manufacturing Co. Ltd.
Ostrolenk Faber Gerb & Soffen, LLP
Pascal Robert
Takaoka Dean
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