Dielectric resonator and dielectric filter using the same

Details Dielectric resonator and dielectric filter using the same Dielectric resonator and dielectric filter using the same

1999-04-06

2001-01-16

Pascal, Robert (Department: 2817)

Wave transmission lines and networks

Resonators

Dielectric type

C333S202000

Reexamination Certificate

active

06175286

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dielectric resonator and a dielectric filter suitable for use in an electronic device such as a shared device of transmission and reception signals (duplexer) for a cellular base station.
2. Description of the Related Art
As shown in
FIG. 9
, generally, a conventional dielectric resonator is constructed in such a manner that a cylindrical dielectric block
100
made of ceramics is fixed on the bottom of a metal casing body
101
and the opening of the metal casing body
101
is covered with a casing lid
101
a
for keeping an electromagnetic field energy inside.
An input connector
102
is attached to, for example, the left-side wall of the metal casing body
101
and an output connector
103
is attached to the right-side wall. The front ends of central conductors
102
a
and
103
a
of the input and output connectors
102
and
103
penetrate the left-side and right-side walls, respectively, and are projected to the inside of the metal casing body
101
. One ends of coil-shaped coupling loops
104
and
105
are soldered to the front ends of the central conductors
102
a
and
103
a
, respectively. The other ends of the coupling loops
104
and
105
are fixedly soldered to the metal casing body
101
and connected to the ground.
According to another conventional example, as shown in
FIG. 10
, one ends of almost linear probes
114
and
115
are connected to the central conductors of input and output connectors
112
and
113
, respectively, which project to the inside of a metal casing
111
, the probes
114
and
115
are arranged along the internal circumferencial wall of the metal casing
111
, and the other ends are disposed near the dielectric block
100
.
In a dielectric resonator having such a construction, the coupling loops
104
and
105
or the probes
114
and
115
are magnetically coupled to the dielectric block
100
. When an electric signal is supplied to the coupling loop
104
or the probe
114
, a magnetic field is produced in the coupling loop
104
or the probe
114
. By the magnetic energy, the dielectric block
100
is excited, a current is passed through the dielectric block
100
, and a magnetic field is produced. By the magnetic energy, a magnetic field is generated, a current is passed through the coupling loop
105
or the probe
115
on the output side, and an electric signal is outputted from the output side connector
103
or
113
.
In a conventional dielectric resonator as described above, the coupling loops
104
and
105
or the probes
114
and
115
a re not structurally resistant to vibration. When the dielectric resonator is subjected to vibration, the coupling loops
104
and
105
or the probes
114
and
115
vibrate more than the dielectric resonator
100
. Consequently, there is an inconvenience such that the degree of coupling to the dielectric block
100
changes.
In order to deal with it, a method of fixing the coupling loops
104
and
105
or the probes
114
and
115
so as not to vibrate by using an adhesive such as paraffin can be considered. However, a problem such that deterioration in performance occurs due to the application of the adhesive arises.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a dielectric resonator which is not easily influenced by vibration and can have excellent performance stably.
In order to solve the problems, a dielectric resonator of the invention comprises exciting means in which a pillar-shaped dielectric block is housed in a conductive casing in a state where the dielectric block is electrically connected to the casing and which produces a magnetic field on a plane perpendicularly crossing the axial direction of the dielectric block through which a current is passed, wherein the exciting means includes a supporting member which is fixed to the casing and at least one electrode pattern which is connected to an input or output terminal and formed on the supporting member.
Since the exciting means is fixed to the casing, the dielectric resonator of the invention is not easily influenced by vibration, so that stable performance can be obtained.
It is preferable that the supporting member is made of a dielectric and an electrode pattern made of a conductive material is formed on the supporting member, so that the physical dimension of the exciting means can be reduced by shortening the wavelength of the dielectric. As a dielectric, plastics such as Teflon or epoxy resin and ceramics are desirable. From the viewpoint of the effects produced by shortening the wavelength, a dielectric of ceramics having a high dielectric constant is the most preferred. By disposing such a supporting member in the casing, the magnetic energy is radiated effectively in the conductive casing. Consequently, the dielectric block can be efficiently excited.
It is preferable to construct in such a manner that the electrode pattern is constructed by two electrode patterns sandwiching the supporting member, one of the electrode patterns is connected to an input terminal or an output terminal, and the other electrode pattern is connected to the ground. By forming the two electrode patterns in a shape having opposed parts over the supporting member, a dielectric resonator having sharp attenuation characteristics in which there are attenuation regions on both sides of a pass band frequency region can be obtained.
A configuration such that a supporting member is made of a dielectric, an electrode pattern formed on the supporting member has the shape comprising two electrode bands which are spaced in parallel and a coupling band which couples one ends on the same side of the two electrode bands, and the input and output terminals are connected to the electrode pattern can be also employed.
For example, when a coupling band formed in an almost U shape on the top face of the supporting member and two electrode bands which are continued from both ends of the coupling band and spaced in parallel on one side face which faces the dielectric block are formed, a strong magnetic field can be produced near the dielectric block.
When a coupling band linearly formed on the top face of the supporting member and two electrode bands which are continued from both ends of the coupling band and formed on opposed two side faces are formed, a strong magnetic field can be produced by the electrode bands.
By using the dielectric resonator of the invention as input and output units of a dielectric filter, a dielectric filter which is not easily influenced by vibration and has excellent stability can be obtained.


REFERENCES:
patent: 4686496 (1987-08-01), Syrett et al.
patent: 4942377 (1990-07-01), Ishikawa et al.
patent: 5008640 (1991-04-01), Accatino et al.
patent: 5457087 (1995-10-01), Dorothy et al.
patent: 5680080 (1997-10-01), Nishiyama et al.
patent: 5831496 (1998-11-01), Sonoda et al.
patent: 6052041 (2000-04-01), Ishikawa et al.

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