Dielectric filter having non-conductive adjusting regions

Details Dielectric filter having non-conductive adjusting regions Dielectric filter having non-conductive adjusting regions

2000-06-08

2002-10-15

Lee, Benny (Department: 2817)

Wave transmission lines and networks

Coupling networks

Wave filters including long line elements

C333S207000, C333S206000

Reexamination Certificate

active

06466109

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a dielectric filter having at least one dielectric resonator, the dielectric resonator having an internal conductor which is formed within a dielectric block and an external conductor which is formed on the outside of the dielectric block.
2. Description of Related Art
Filters for use in, for example, the microwave band, include a dielectric filter, in which a resonator electrode is formed within a dielectric block and an earth electrode is formed on the outside face of the dielectric block, and a so-called Triplate™ type of dielectric resonator with strip lines located opposite to each other on respective main faces of a dielectric substrate, the strip lines serving respectively as a signal strip line on one main face and an earth electrode on the other main face.
FIG. 39
shows an exploded perspective view of the construction of the conventional general dielectric resonator using a dielectric block. In
FIG. 39
, reference numeral
40
is a six-sided dielectric block with three internal conductor holes
46
,
47
,
48
each having an internal conductor provided therein and coupling holes
49
,
50
which are provided between the internal conductor holes
46
,
46
,
48
. The internal conductors are formed on the inside surfaces of the internal conductor holes
46
,
47
,
48
, and an external conductor
51
is formed on five faces of the dielectric block
40
except for an open face
52
. Reference numerals
53
,
54
are so-called resin pins, each being composed of resin portions
53
a
,
54
a
and signal input, output terminals
53
b
,
54
b
. Two resin pins
53
,
54
are inserted into the internal conductor holes
46
,
48
from the open face side of the dielectric block
40
so that the terminals
53
b
,
54
b
are coupled capacitively to the corresponding internal conductors within the internal conductor holes
46
,
48
. Reference numeral
55
is a case for retaining the dielectric block
40
and the resin pins
53
,
54
and also, for covering the open face portion of the dielectric block
40
. The resin pins
53
,
54
are respectively inserted into the dielectric block
40
so as to be covered by the case
55
, and also, the whole arrangement is integrated by soldering the case
55
to the external conductor
51
. For mounting the dielectric resonator on a circuit substrate, the projecting portions
55
a
,
55
b
of the case
55
function as an earth terminal.
As shown in
FIG. 39
, many components such as input, output terminals
53
b
,
54
b
, case
55
and so on, are necessary if a plurality of resonators are to be formed in a single dielectric block. The assembly steps therefore become complicated. Moreover, it is necessary to attach a lead wire to the component when mounting the completed product on a circuit substrate. Therefore, surface mounting cannot be effected, as it can with other electronic components, so as to mount a plurality of these completed products on the same circuit substrate. Thus, it is difficult to provide an assembly which is low in height.
Further, if the case
55
is not used, the external conductor
51
of the dielectric block
40
is directly connected to the earth electrode on the circuit substrate, so that the open face
52
is exposed, and thus, electromagnetic field leakage occurs at this location. Thus, when a metallic object approaches the open face
52
, the metallic object influences this electromagnetic field. Further, since the resonator is coupled with this electromagnetic field, the desired characteristics of the dielectric resonator cannot be obtained.
SUMMARY OF THE INVENTION
Accordingly, the present invention has been developed with a view to substantially eliminating the above discussed drawbacks that are inherent in the prior art, and has for its essential object to provide an improved dielectric resonator.
Another important object of the present invention is to provide an improved dielectric resonator which can be surface mounted on the circuit substrate without the use of resin pins and a case as individual parts, as required by the prior art device shown in FIG.
39
.
Still another object of the present invention is to provide a dielectric resonator in which electromagnetic field leakage between the inside and the outside of the resonator near the opening portion is reduced, so as to remove the problem caused by the above described electromagnetic field leakage.
A further object of the invention is to provide a method by which a resonator can be adjusted with ease and accuracy so as to have desired characteristics.
A further object of the present invention is to provide a dielectric resonator in which it is easier to obtain floating capacitance by a comparatively simple working or molding operation.
In accomplishing these and other objects, a dielectric resonator in accordance with a first aspect of the invention is provided having a non-conductive portion formed in at least one internal conductor near one end face of the above described dielectric block, and signal input, output electrodes for providing capacitive connection with the above described internal conductor are provided on the outer surface of the dielectric block. The dielectric resonator includes at least one internal conductor hole, or a plurality of internal conductor holes, within the dielectric block, the external conductor being formed on the outside of the above described dielectric block.
In the dielectric resonator of the first aspect of the invention, the non-conductive portion in the internal conductor hole is provided near one end of the at least one hole, or the plurality of holes, of the dielectric resonator, and the signal input, output electrodes effect capacitive connection with the internal conductor. A tip end capacitance is created at the non-conductive portion in the at least one internal conductor hole so as to provide comb-line coupling or interdigital coupling between the adjacent resonators. In this construction, the conductor is present on each end face of the dielectric body, so that large electromagnetic field leakage is avoided.
As coupling holes are not required, the whole arrangement can easily be made smaller in size. As the signal input, output electrodes are provided so as to provide a capacitive connection with the internal conductor, the signal input, output terminals are not required to be separate, individual parts. The external conductor can be connected with the earth electrode on the circuit substrate by surface mounting, and also, the signal input, output electrodes can be similarly connected with the signal line on the circuit substrate.
A dielectric resonator of a second aspect of the invention is characterized in that the dielectric filter described in accordance with the first aspect of the invention is an approximately six-sided unit and the above described signal input, output electrodes may be formed only on a circuit substrate mounting face thereof.
In the dielectric resonator of the second aspect of the invention, the above described signal input, output electrodes may be formed only on the mounting face which is to be mounted to the circuit substrate. Therefore, electromagnetic field leakage of the signal input, output electrodes is reduced when the dielectric resonator is mounted on the substrate, the resonator characteristics are less changed by the influence of external metallic objects, and no unnecessary connections with other circuit portions are required, thereby simplifying the circuit design and assembly operation. Further, pattern formation on the circuit substrate is simplified, because the signal input, output electrodes are formed within one plane.
A dielectric resonator of a third aspect of the invention has a plurality of internal conductors formed in holes within a dielectric block, an external conductor is formed on the outside of the dielectric block, one end face of the above-described dielectric block being a short-circuit face where the internal conductors within the holes are short-c

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