Wave transmission lines and networks – Plural channel systems – Having branched circuits
Reexamination Certificate
2000-07-28
2003-02-25
Nguyen, Patricia (Department: 2817)
Wave transmission lines and networks
Plural channel systems
Having branched circuits
C333S202000, C333S206000
Reexamination Certificate
active
06525625
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dielectric duplexer and a communication apparatus using the dielectric duplexer.
2. Description of the Related Art
Conventional filters designed for use in, for example, microwave bands are configured to have resonance lines provided on a dielectric board, a dielectric block, or the like. For example, for bandpass filters, the central frequency of a passing band, passing-band widths, attenuation-pole frequencies, and the like are designed to meet required technical specifications. As particular examples, dielectric filters designed so as to control characteristics over transient regions from passing bands to attenuation bands have been proposed by Japanese Unexamined Patent Application Publications Nos. 62-161202 and 7-321508.
Japanese Unexamined Patent Application Publication No. 62-161202 proposed an antenna duplexer configured of two bandpass filters. One of the bandpass filters has attenuation characteristics with a greater gradient in the direction from a passing band to an attenuation band on the low-band side than in the direction from the passing band to an attenuation band on the high-band side. In contrast, the other of the bandpass filters has attenuation characteristics with a greater gradient in the direction from a passing band to an attenuation band on the high-band side than in the direction from the passing band to an attenuation band on the low-band side.
Japanese Unexamined Patent Application Publication No. 7-321508 proposed a bandpass filter configured of resonators coupled by means of a concentrated-constant-type coupling element. In the bandpass filter, to increase amounts of attenuation in attenuation bands, magnetic coupling is used for interstage coupling in a low-band-side bandpass filter, and capacitive coupling is used for interstage coupling on a high-band-side bandpass filter.
In order to use each of these conventional dielectric filters as an antenna duplexer, a configuration can be such that attenuation poles are individually provided in a high band of the low-band-side bandpass filter and in a low band of the high-band-side bandpass filter. This configuration can produce attenuation characteristics which sharply change in a direction from one of the passing bands to the other one of the passing bands. However, a problem arises in that the antenna duplexer is influenced by waves (noise waves) in an adjacent frequency band: namely, in a band of higher or lower frequency than the high or low passing bands.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a dielectric duplexer that has first and second filters passing two adjacent bands and that is not influenced by signals in bands that are adjacent to and outside the two passing bands.
Another object of the present invention is to provide a communication apparatus using the aforementioned dielectric duplexer.
To these ends, according to one aspect of the present invention, there is provided a dielectric duplexer, comprising: a first filter having a plurality of resonance lines provided on a dielectric member, for passing a lower-side band; and a second filter having a plurality of resonance lines provided on the dielectric member, for passing a higher-side band; wherein adjacent resonance lines of the first filter are coupled at their predetermined portions to each other by distributed-constant-inductive coupling, so as to generate an attenuation pole in the high-frequency side of the passing band, while adjacent resonance lines of the second filter are coupled at their predetermined portions to each other by distributed-constant-capacitive coupling, so as to generate an attenuation pole in the low-frequency side of the passing band, and wherein adjacent resonance lines of the second filter are coupled at their other portions to each other by distributed-constant-inductive coupling, so as to generate an attenuation pole also in the high-frequency side of the passing band of the second filter.
According to another aspect of the present invention, there is provided a dielectric duplexer, comprising: a first filter having a plurality of resonance lines provided on a dielectric member, for passing a lower-side band; and a second filter having a plurality of resonance lines provided on the dielectric member, for passing a higher-side band; wherein adjacent resonance lines of the first filter are coupled at their predetermined portions to each other by distributed-constant-inductive coupling, so as to generate an attenuation pole in the high-frequency side of the passing band, while adjacent resonance lines of the second filter are coupled at their predetermined portions to each other by distributed-constant-capacitive coupling, so as to generate an attenuation pole in the low-frequency side of the passing band, and wherein adjacent resonance lines of the first filter are coupled at their other portions to each other by distributed-constant-capacitive coupling, so as to generate an attenuation pole also in the low-frequency side of the passing band of the first filter.
With these features, it is possible to realize sharp attenuations not only in the higher-frequency side of the first filter that passes lower frequency band and the lower-frequency side of the second filter that passes higher frequency band, but also at the lower-frequency side of the first filter and at the higher-frequency side of the second filter, whereby influences of signals which are outside and adjacent to the two passing bands can be significantly suppressed.
The arrangement may be such that the dielectric member is a substantially rectangular parallelepiped dielectric block, and the resonance lines are constituted by inner conductors in resonator holes formed in the dielectric block, and wherein the distributed-constant-inductive coupling or the distributed-constant-capacitive coupling is implemented by determining the distance between portions of adjacent resonator holes near the open-circuit ends of the resonator holes and the distance between portions of the adjacent resonator holes near the short-circuit ends of the resonator holes.
With this arrangement, it is possible to obtain a dielectric multiplexer which is easy to manufacture and which can suppress unnecessary frequency signals outside the two passing bands, by using a single dielectric block and suitably determining the configurations of the resonator holes.
The arrangement also may be such that the dielectric member is a substantially rectangular parallelepiped dielectric block, and the resonance lines are constituted by inner conductors in resonator holes formed in the dielectric block, and wherein the distributed-constant-inductive coupling or the distributed-constant-capacitive coupling is implemented by determining the effective inductivity between portions of adjacent resonator holes near the open-circuit ends of the resonator holes and the effective inductivity between portions of the adjacent resonator holes near the short-circuit ends of the resonator holes.
With this arrangement, it is possible to obtain a dielectric multiplexer which can suppress unnecessary frequency signals outside the two passing bands, by using a single dielectric block and by suitably determining the effective inductivities at predetermined portions of the dielectric block. Thus, the characteristics of the dielectric duplexer can be determined by the outer shape of the dielectric block, and can easily be adjusted from the exterior of the dielectric block.
The arrangement also may be such that the dielectric member is a substantially rectangular parallelepiped dielectric block, and the resonance lines are constituted by inner conductors in resonator holes formed in the dielectric block, and wherein the distributed-constant-inductive coupling or the distributed-constant-capacitive coupling is implemented by determining the opposing area of the inner conductors of adjacent resonator holes near the open-circuit ends of the resonator holes and the opposing area
Ishihara Jinsei
Kato Hideyuki
Kuroda Katsuhito
Tsukamoto Hideki
Dickstein Shapiro Morin & Oshinsky
Murata Mfg. Co. Ltd
Nguyen Patricia
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