Murata Manufacturing Co., Ltd.

Shohachi Nishijima

Hideyuki Kato

Motoharu Hiroshima

Haruo Matsumoto

Katsuhito Kuroda

Kikuo Tsunoda

Hiromi Ogura

A &#x3bb;/2 resonator comprises an inner conductor formed hole having an inner conductor with both open-ends, formed therein, and &#x3bb;/4 resonators comprise inner conductor formed holes having inner conductors with one short-circuited ends and the other open ends, respectively. The resonators are coupled, whereby a terminal electrode connected to the vicinity of the one open end of one of the &#x3bb;/4 resonators functions as an unbalanced terminal, and terminal electrodes connected to both open ends of the &#x3bb;/2 resonator function as balanced terminals.

Dielectric filter, dielectric duplexer, and communication apparatus

A dielectric filter including: a &lgr;/2 resonator for generating resonance of &frac12;-wavelength at a predetermined frequency, having both ends open-circuited or short-circuited; and a pair &lgr;/4 resonators respectively for generating resonance of &frac14;-wavelength at a frequency substantially equal to the predetermined frequency, each having one end open-circuited and the other end short-circuited; wherein the pair of &lgr;/4 resonators are disposed in proximity to each of both ends from the vicinity of the center of the &lgr;/2 resonator; a terminal coupling to the &lgr;/2 resonator is provided as an unbalanced terminal; and terminals coupling to the pair of &lgr;/4 resonators is used as a balanced terminal. In the above filter, the balanced-type input/output of signals can be performed without using a balun.

A dielectric filter, a dielectric duplexer, and a communication apparatus using them allow balanced input and/or output to be implemented without requiring a balun. Using a dielectric block, two &lgr;/2 resonators are individually formed using either inner-conductor-forming openings with inner conductors therein, or stripline-type conductors, both of said conductors having both ends open-circuited, and said conductors being capacitively coupled together. Terminal electrodes coupled to the vicinities of two open-circuited ends of one of the resonators are used as balanced terminals on one side, and terminal electrodes coupled to the vicinities of the two open-circuited ends of the other one of the resonators are used as balanced terminals on the other side.

Inner conductor formation holes having inner conductors formed on the inner walls thereof are formed in a dielectric block. Both of the ends of one of the inner conductors are open and led out as terminal electrodes which function as balanced ports. Both of the ends of another inner conductor are connected to an outer conductor to be grounded, and the center portion of the inner conductor between the ends is led out as a terminal electrode which functions as an unbalanced port. The circuit can also be realized with striplines or microstriplines on a dielectric substrate. Thus, a balanced-unbalanced converter having these terminal electrodes as balanced and unbalanced ports is formed.

Balanced-unbalanced converting circuit, balanced-unbalanced converter, and communication device including the same

A dielectric filter and a dielectric duplexer adapted to two frequency bands formed by using a single component are disclose, in addition to a communication apparatus using the same. In this case, since a dielectric block used as the single component can be easily molded and grasped, production efficiency can be enhanced. The dielectric duplexer adaptable to two frequency bands is formed by disposing inner-conductor-formed holes acting as &lgr;/2 resonators and &lgr;/4 resonators in the single dielectric block.

Dielectric filter, dielectric duplexer, and communication apparatus using the same

A &lgr;/2 resonator comprises an inner conductor formed hole having an inner conductor with both open-ends, formed therein, and &lgr;/4 resonators comprise inner conductor formed holes having inner conductors with one short-circuited ends and the other open ends, respectively. The resonators are coupled, whereby a terminal electrode connected to the vicinity of the one open end of one of the &lgr;/4 resonators functions as an unbalanced terminal, and terminal electrodes connected to both open ends of the &lgr;/2 resonator function as balanced terminals.

There is provided a dielectric filter comprising: a dielectric block; a plurality of resonance lines aligned substantially in parallel in the dielectric block; and a conductor line disposed in the dielectric block so as not to be parallel to the longitudinal direction of the resonance lines, the conductor line being served as a device having an inductance component which is connected to a circuit comprising the resonance lines.

Dielectric filter, composite dielectric filter, duplexer, and communication apparatus

Dielectric filter, composite dielectric filter, antenna duplexer, and communication apparatus

On the internal surface of each of the through-holes formed in a dielectric block, an internal conductor is formed, while on the external surface except the top surface, an external conductor is formed. The internal conductors, together with the external conductor and the dielectric block, form dielectric resonators with 1/4-wavelength using the top and bottom surfaces of the dielectric block as an open surface and a short surface, respectively. Each of the through-holes has a large-diameter hole portion and a small-diameter hole portion and also has a coupling adjustment hole portion for the purpose of a fine adjustment of electromagnetic coupling between adjacent the dielectric resonators.

Dielectric filter with through-hole having large and small diameter

The invention provides a technique of adjusting the mutual capacitance of resonant through-holes in a dielectric filter while maintaining the shape of input/output electrodes constant without causing a change in the external capacitance. In one such dielectric filter, a plurality of resonant through-holes are formed in a dielectric block, each resonant through-hole including a large-diameter hole and a small-diameter hole, a step being formed at the boundary between the large-diameter hole and the small-diameter hole, the inner wall of each said resonant through-hole being covered with an inner conductor; an outer conductor formed on outer surfaces of said dielectric block except for an end surface in which ends of the respective large-diameter holes are located; and input/output electrodes which are formed on a side face such that said input/output electrodes are coupled with said large-diameter holes; wherein the center axes of said large-diameter holes are deviated from the center axes of the corresponding small-diameter holes, thereby increasing the mutual capacitance between the large-diameter holes.

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Komatsu, Japan

Shohachi Nishijima