Wave transmission lines and networks – Coupling networks – Wave filters including long line elements
Patent
1995-11-28
1997-11-25
Lee, Benny
Wave transmission lines and networks
Coupling networks
Wave filters including long line elements
333206, 333222, 333224, 333232, H01P 120
Patent
active
056916752
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invneiton relates to a resonator that is used for the elimination of noise, the splitting and synthesis of signals, etc., in radio communication devices, broadcast devices, and so on, and also relates to a filter comprising this resonator.
BACKGROUND ART
Resonators composed of capacitors and coils which are lumped-parameter circuit elements, or helical resonators have been conventionally used in relatively low frequency bands, such as short wave and ultrashort wave bands.
FIG. 1 is a vertical cross section of a conventional helical resonator, and FIG. 2 is a horizontal cross section thereof.
This helical resonator comprises an external conductor 201; a capacity formation electrode 203; insulators 204.sub.1 and 204.sub.2 ; a helical resonance element 202 at one end mechanically fixed to and electrically connected with the inside wall of the external conductor 201, wound coil-like in its middle portion, attached at the other end to the capacity formation electrode 203, and fixed to the inside wall of the external conductor 201 via the insulators 204.sub.1 and 204.sub.2 ; a movable electrode 205; a drive screw 206 to one end of which the movable electrode 205 is attached, and which passes through the external conductor 201; a lock nut 207 that is used to fix the drive screw 206 to the external conductor 201; and input/output coupling elements and input/output terminals (not shown).
With this helical resonance element, the resonance frequency can be finely tuned by rotating the drive screw 206 forward or backward to move the movable electrode 205 ahead or back so that the capacity of the electrode 203 can be varied.
The conventional resonator described above has the following drawbacks.
Since the helical resonance element 202 is formed by the winding of a metallic wire or a relatively thin rod-shaped conductor in the form of a coil, not only is the heat-radiating surface area of the helical resonance element 202 itself small, but the thermal conductivity into the external conductor 201 is poor, so the heat produced by power loss in the helical resonance element 202 is not effectively radiated from the helical resonance element 202 and the external conductor 201, and the resonance frequency fluctuates as a result of distortion due to the elevated temperature of the various constituent components of the resonator.
The ends of the helical resonance element 202 are directly or indirectly supported by and fixed to the inside wall of the external conductor 201, but the middle portion is not supported by any support, and is instead formed so that it maintains a coiled posture by its own rigidity, so vibration resistance is poor, fabrication is difficult, and the cost is high.
When the diameter of the wire or rod that forms the helical resonance element 202 is relatively large, distortion of the helical resonance element 202 itself due to the elevated temperature of the helical resonance element 202 repeatedly applies mechanical strain to the insulators 204.sub.1 and 204.sub.2 through the electrode 203, and in severe cases the insulators 204.sub.1 and 204.sub.2 would be broken.
Because of its high impedance, a helical resonance element has inferior withstand voltage characteristics.
When a filter is constructed from such a helical resonance element, the various above-mentioned drawbacks encountered with a helical resonance element appears as drawbacks directly in the filter.
DISCLOSURE OF THE INVENTION
It is object of the present invention to provide a resonator in which heat is effectively radiated away from the resonance capacity element and external conductor, the fluctuation in resonance frequency is extremely small, the vibration resistance is excellent, and the impedance is low, and to provide a filter in which this resonator is used.
A resonator according to the present invention comprises:
an external conductor;
a resonance capacity element comprising a dielectric plate fixed at the upper and lower ends to the upper and lower walls, respectively, of the external conductor, an
REFERENCES:
patent: 4268809 (1981-05-01), Makimoto et al.
patent: 4568985 (1986-02-01), Reed
patent: 4603311 (1986-07-01), Mage
patent: 4613838 (1986-09-01), Wada et al.
patent: 4614925 (1986-09-01), Kane
patent: 4631506 (1986-12-01), Makimoto et al.
patent: 4660005 (1987-04-01), Hutchinson
Gambino Darius
Lee Benny
Nihon Dengyo Kosaku Co., Ltd.
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