Dielectric filter having notch pattern

Details Dielectric filter having notch pattern Dielectric filter having notch pattern

2000-12-28

2003-07-22

Lee, Benny (Department: 2817)

Wave transmission lines and networks

Coupling networks

Wave filters including long line elements

C333S206000

Reexamination Certificate

active

06597263

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a dielectric filter installed in a terminal of a radio communication system; and, more particularly, to a dielectric filter having a notch pattern, in which an attenuation characteristic on a stop band can be improved and simultaneously a coupling quantity control between respective resonators can become easy, by gaining a high attenuation pole even without increasing the number of resonators.
PRIOR ART OF THE INVENTION
It is known that in order to improve frequency efficiency in the terminals of a radio communication system, mutually neighboring transmission and reception frequency bands may be used, such that a high attenuation characteristic on a stop band is required in a filter used in such terminals.
Referring to
FIGS. 1 through 3
, a dielectric filter based on first through third embodiments of a conventional technique may be described as follows.
The dielectric filter based on the first embodiment of the conventional technique shown in
FIG. 1
includes a dielectric block
10
and first through sixth resonators
11
,
12
,
13
,
14
,
15
and
16
which are formed, piercing through upper and lower faces of the dielectric block
10
.
Each resonator
11
through
16
is formed by plating an inner wall face of a through-hole with conductive metal, the through-hole being formed by piercing through the upper and lower faces of the dielectric block
10
. All the wall faces of the dielectric block
10
except the upper face are plated with the conductive metal. The upper face of the dielectric block
10
is electrically opened, and the rest of the wall faces, except the upper face, of the dielectric block
10
are formed as ground faces.
On the upper face of the dielectric block
10
, a plurality of slots
17
for controlling a coupling quantity between two resonators formed adjacently to each other, and a reactance
18
for improving an attenuation characteristic on a stop band of the dielectric filter are formed. An inner wall face of each slot
17
is plated with conductive metal, and the coupling quantity between the resonators of the filter can be controlled by controlling a size of the slot
17
. The reactance
18
connects two resonators, namely, a second resonator
12
with a fifth resonator
15
, and resonators
13
,
14
not connected by the reactance
18
exist between two resonators, namely, the second and fifth resonators
12
,
15
, which are connected by the reactance
18
. This reactance
18
is composed of coil, a capacitor and a lead wire etc.
The dielectric filter based on the second embodiment of the conventional technique shown in
FIG. 2
includes a dielectric block
20
having a formation of first through seventh resonators
21
,
22
,
23
,
24
,
25
,
26
and
27
which are formed, piercing through upper and lower faces thereof.
A first transmission line
28
having an electric length of &lgr;/4 is formed between the first and second resonators
21
,
22
, &lgr; being a wavelength of resonance frequency. Also, a second transmission line
29
having an electric length of &lgr;/4 is formed between the second and third resonators
22
,
23
. Such a conventional dielectric filter has numerous attenuation pole characteristic through an inverter circuit. At this time, a magnetic field coupling is formed between the respective resonators, and such respective resonators are separately tuned so as to have a desired filter characteristic.
If the dielectric filter based on the second embodiment of the conventional technique is applied to a duplexer, a plurality of resonance polar points can be formed by forming numerous holes.
The dielectric filter based on the third embodiment of the conventional technique shown in
FIG. 3
includes a dielectric block
30
in which an electric opening face is formed on an upper face thereof, and on its side wall and lower face, ground faces plated with the conductive metal are formed, and in which first through fourth resonators
31
,
32
,
33
,
34
formed piercing through the upper and lower faces thereof are also provided.
On the upper face of the dielectric block
30
as the opening face, there are formed first through fourth resonator patterns
31
a,
32
a,
33
a
and
34
a
connected to upper parts of the respective resonators
31
through
34
, and two of first metal patterns
35
provided between the second and third resonator patterns
32
a,
33
a
and between the third and fourth resonator patterns
33
a,
34
a.
Both end parts of the first metal pattern
35
are individually connected to both side wall faces as the ground face of the dielectric block
30
. Further, a second metal pattern
36
is formed between the first and second resonator patterns
31
a,
32
a,
and one end part of the second metal pattern
36
is connected to one side wall face of the dielectric block
30
, and another end part provides an opening part
37
which is distanced by a constant interval T from another side wall face of the dielectric block
30
.
In such conventional dielectric filter, a loading capacitance is formed between the respective metal patterns
35
and the second through fourth resonator patterns
32
a
to
34
a,
and a loading capacitance is also formed between the first and second resonator patterns
31
a,
32
a.
Herewith, the loading capacitance between the first and second resonator patterns
31
a,
32
a
is controlled by a size of the opening part
37
formed by the second metal pattern
36
. In other words, the loading capacitance between the first and second resonator patterns
31
a,
32
a
can be controlled by controlling a size of the opening part
37
.
In the dielectric filter based on the first embodiment of the conventional technique, more than three resonators must be formed to improve the attenuation characteristic on the stop band by using the reactance, such that the size of the filter is increased and it is difficult to reduce or enlarge a size of a slot that has already been processed. Thus, it is difficult to control a coupling quantity between the resonators after a process of the filter.
Furthermore, in case that the dielectric filter based on the conventional second embodiment is applied to a duplexer, an impedance unbalance unacceptable in an interface of transmission/reception filters occurs from an attenuation pole formed on a pass band end portion of the transmission filter coupled with the reception filter. That is, the number of the attenuation poles is restricted as a transmission zero, to thereby drop a filter characteristic on the stop band, and due to such reasons, some restriction is caused in designing the transmission/reception filters of the duplexer.
In the dielectric filter based on the conventional third embodiment, the coupling quantity can be controlled by controlling a size of the opening part formed by the second metal pattern, but the number of the resonators must be increased to improve the attenuation characteristic on the stop band. Therefore, there is a problem in that the filter becomes large in size.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide a dielectric filter having a notch pattern capable of improving an attenuation characteristic on a stop band, without increasing the number of resonators, through an embodiment for gaining a coupling not only between neighboring resonators but also between resonators which are not adjacent to one another, so as to obtain a high attenuation pole on a frequency band adjacent to transmission and reception frequency.
Another object of the present invention is to provide a dielectric filter having a notch pattern capable of easily controlling a coupling between a ground face and a resonator necessary for an operation of a filter and a coupling between a resonator and a resonator.
Still another object of the present invention is to provide a dielectric filter having a notch pattern capable of miniaturizing a filter without increasing the number of resonators.
In accordance with the present invention for achieving the above objects, the die

Affiliated with

Also associated with

Rating

Dielectric filter having notch pattern does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Dielectric filter having notch pattern, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dielectric filter having notch pattern will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3037067