JPH03284001A - Dielectric filter - Google Patents

Abstract

PURPOSE:To stabilize the degree of coupling of each resonator by forming a coupling groove at the side plane of a dielectric resonator in which an inner conductor is provided on the through hole inner plane of a dielectric block and an outer conductor on the outer plane, and arranging a sub transmission line substrate to be connected to the inner conductor. CONSTITUTION:The dielectric filters 10 are coupled electrically and in capacitive fashion through coupling holes 6a, 6b, 6c... formed on the connecting side planes 4a, 4b, 4c... between neighboring dielectric resonators 1a and 1b, 1b and 1c,.... The upper planes of the resonators 1a, 1b, 1c... form an open end face A on which the dielectric block is exposed, and the confronting lower plane forms a short-circuited terminal plane B. The inner conductors 3a, 3b, 3c... are formed on the inner planes of the through holes 2a, 2b, 2c... and the outer conductors 5a, 5b, 5c... are formed on the outer plane of the block. At the sub transmission line substrate 7, through hole insertion parts 11a, 11b, 11d, and 11e to be inserted from one terminal part to the through holes 2a, 2b, 2d, and 2e are formed, and the conductive patterns 8a, 8b, and 8c of a sub transmission line and capacitor electrodes 9a, 9e, 10a, and 10e for input/output are formed on one main plane of the substrate 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dielectric filter, and more particularly, to a polarized dielectric filter that improves the reliability of transmission and reception.

[Prior art]

BACKGROUND ART Dielectric filters have conventionally been widely used in portable telephones such as personal radios and car telephones that utilize microwaves because of their small size and high selectivity. In particular, for mobile phones, for example, the center frequency for transmission is 911.
5 MHz, the band is 27.0 MHz, the reception center frequency is 856.5 MHz, and the band is 27.0 MHz. In order to prevent crosstalk and achieve highly reliable selectivity due to the setting of these transmitting and receiving frequencies,
A polarized dielectric filter that attenuates at a predetermined frequency within a passband is known.

FIG. 3 is an external perspective view of a conventional polarized dielectric filter.

This dielectric filter 30 is composed of a filter section 31 and a sub-transmission line board 36.

The filter section 31 includes a plurality of resonators 31a, 311), 3
It is composed of 1c... These plurality of resonators 31a, 31b, 31c... are connected to through holes 33a, 33
dielectric block 32a in which b, 33c... are formed;
32b, 32c... and through holes 33a133b133
An inner conductor 34a, which is a conductor film formed on the inner surface of C...
34b, 34c... and inner conductors 34a, 34b, 34
Dielectric blocks 32 a, 32 b, 32 c, excluding one end face (open end face) where the opening of c... is exposed.
Outer conductors 35a, 35b, 35 formed on the outer peripheral surface of...
It is formed by c...

Coupling between adjacent resonators 31a, 31b, 31c, etc. is achieved through capacitor electrodes 37a,
37b, 37c... are coupled to each other by interelectrode capacitance.

The sub-transmission line board 36 is made of a substrate having a predetermined dielectric constant, such as alumina, and has conductor insertion portions 38a, 38b, 38C, etc., which are inserted into the inner conductor of the resonator. This board 36 includes conductor insertion portions 38a, 38b, 38.
c... T-shaped capacitor electrode 37a including the top;
37b137C... are formed. and resonator 31a.

Inner conductors 34a, 34b of 31b, 31c...

34c... and 1-character capacitor electrodes 37a, 37b,
37c... are electrically connected, and between each resonator, the interelectrode capacitance of the capacitor electrode, the amount 37a and 37b, 37b and 37
They are connected to each other via c...

Further, the above-mentioned capacitor electrode 3 is provided on the sub-transmission line board 36.
In addition to 7a137b137C..., sub-transmission line pattern 38 for polarization and input/output capacitor electrode 39a
, 39e are formed.

In the figure, a resonator 31b and a resonator 31d are connected by a sub-transmission line pattern 38. That is, the capacitor electrode 37b of the resonator 31b and the capacitor electrode 37d of the resonator 31d are capacitively coupled to the sub-transmission path pattern 38.

[Problem to be solved by the invention]

However, in the above-mentioned polarized dielectric filter 30, since each resonator 31a, 31b, 31c, etc. can be separated individually, the resonator frequency can be easily adjusted. 37a, -37b, 37c・
··Is required. Therefore, when the sub-transmission line board 36 is attached to the filter section 31, for example, the resonator 31c (
The structure is such that unnecessary capacitance is likely to occur, such as unexpected capacitance occurring between the capacitor electrode 37c corresponding to the sub-transmission line 38 (resonator blown by the sub-transmission line 38), The coupling state between the resonators changes. Further, capacitor electrodes 37a and 37b.

37c... and the inner conductors 32a, 32b, 32C... are connected by solder, etc., but this connection state greatly changes the coupling state between the resonators, resulting in unreliable polarization. It was a dielectric filter.

The present invention was devised in view of the above-mentioned problems, and its purpose is to provide a dielectric filter having a highly reliable sub-transmission line structure in which the degree of coupling between a plurality of dielectric blocks is stabilized. Our goal is to provide the following.

[Specific means to achieve the purpose]

In order to achieve the above object of the present invention, an inner conductor is provided on the inner surface of a through hole of a dielectric block, and an outer conductor is provided on the outer surface of the dielectric block except for the open surface where the through hole is formed. A coupling groove is formed on the side surface of the vessel in a direction perpendicular to the through hole, and three or more resonators are connected in series through the coupling groove, and two or more arbitrary resonators are arranged on the open surface side. This dielectric filter is characterized by disposing a substrate on which a sub-transmission path electrode pattern is formed to connect the inner conductors of the dielectric filter.

Furthermore, a through hole is formed in the electrode pattern portion of the substrate on which the sub-transmission line electrode pattern is formed, and the electrode pattern and the inner conductor of the arbitrary resonator are connected by a conductor pin, thereby making it possible to This results in a dielectric filter that further achieves its purpose.

[Effect]

With the above structure, the degree of coupling between the resonators can be achieved by the coupling hole formed by removing a part of the connection side of the dielectric resonator, so the sub-transmission placed on the open end side for polarization can be achieved. It does not have the same effect on the circuit board. In addition, there is no need for capacitor electrodes on the sub-transmission line board, and only the sub-transmission line conductor pattern for polarization is formed, so it can be used as an extremely reliable dielectric filter for the sub-transmission line. Become.

Furthermore, according to the second aspect of the present invention, in particular, the inner conductor and the electrode pattern are electrically connected reliably, and furthermore, the inner conductor and the electrode pattern are connected parallel to the open end face with a predetermined interval that does not generate unnecessary capacitance between the inner conductor and the resonator. Since it can be arranged, it becomes a small, low-profile polarized dielectric filter.

〔Example〕

Hereinafter, the dielectric filter of the present invention will be explained in detail based on the drawings.

FIG. 1 is an exploded perspective view of the dielectric filter of the present invention. In the embodiment, a dielectric filter in which five dielectric resonators are bonded will be described.

The dielectric filter 10 of the present invention has connection sides 4a, 4b between adjacent dielectric resonators 1a and lb, lb and lc...
They are electrically and capacitively coupled by coupling holes 6a, 6b, 6c, . . . formed in 4c, .

The dielectric resonators 1a11b, lc... are Ba0Ti0
2 series, ZrO2-3n02TiO2 series, BaOSm20
: + - Consists of a dielectric block made of Tio2-based, BaO-Nd203-TiOz-based, or CaO-TiO2-3i02-based ceramic having a predetermined dielectric constant, and is set at a predetermined height depending on the resonance frequency.

The upper surfaces of the dielectric resonators 1a, lb, lc... are open end surfaces A in which the ceramic material of the dielectric block is partially or completely exposed, and the lower surfaces opposite thereto are short-circuited end surfaces B.
It becomes. In addition, each dielectric resonator 1a, lb, lc
...through hole 2a.

2b, 2c... are formed to penetrate from the open end surface A to the short-circuited end surface B, and the inner conductor 3a- is formed on the inner surface thereof.

3b, 3c... are formed. Furthermore, outer conductors 5a, 5b, 5c, . . . are formed on the outer peripheral surface of the dielectric block other than the open end surface A and the coupling holes 6a, 6b, 6c, .

These inner conductors 3a, 3b, 3c..., outer conductors 5a, 5b
, 5c... are formed by printing and firing silver, copper, or the like. a single resonator, e.g. resonator 1a
Focusing only on the L-C, one L-C is A resonant circuit will be constructed. The same applies to the other resonators 1b, lc, . . . .

The coupling hole 6a is formed by forming the outer conductor 5a on the dielectric ceramic block body of the resonators 1a and 1b and then removing it by machining, and when the two resonators 1a and 1b are connected, the coupling hole 6a It becomes 6a.

The sub-transmission line substrate 7 is made of a ceramic substrate with a predetermined dielectric constant, and is connected to predetermined resonators la, 1b, ld from one end of the substrate 7.
, le through-hole insertion parts 11a, llb inserted into the through-holes 2a, 2b, 2d, 2e.

A lid and a lie are formed. Further, conductive patterns 8a, 8b, 8c of sub-transmission paths and input/output capacitor electrodes 9a, 9e, 1Oa, 10e are formed on the entire surface of the substrate 7. Incidentally, the conductive patterns 8a, 8c and the input/output capacitor electrodes 9a, 9e are connected to the resonators 1a, lb, l.
In order to connect to the inner conductors 3a, 3b, 3d, and 3e of d and le, they are formed to extend to the through hole insertion portions 11a, llb, lid, and lie.

Through-hole insertion portion 11aX1 of such sub-transmission line board 7
l b, 11 d, 11 e are resonators 1a, I
b.

Through holes 2a, 2b, 2d from the open end surface A side of 1d, 1e
, 2e. As a result, the inner conductors 3b and 3d of the resonators lb and ld are connected to the sub-transmission line 8 (8a, 8b,
8c).

According to the above structure, each resonator is coupled to the sub-transmission line board 7.
Since this is done on the side of the resonator without affecting the transmission, the degree of coupling between each resonator will not change, and the transmission characteristics of the conductor pattern 8 of the sub-transmission line will not change at all.
This means that stable polarization, ie, attenuation at a predetermined frequency, has been achieved.

Another Embodiment FIG. 2 is an exploded perspective view of another embodiment of the polarized dielectric filter of the present invention. Note that the same parts as in the previous embodiment are given the same reference numerals.

In the previous embodiment, the inner conductors 3b, 3d, 3a, 3e and the conductor patterns 8a, 8c and The capacitor electrodes 9a, 9b can be connected by soldering. However, some unevenness may occur depending on the amount of solder and the soldering conditions, and the characteristics may change depending on the connection state.

On the other hand, in this embodiment, the sub-transmission line board 7 is arranged in parallel with a slight gap from the open end surface A, and the sub-transmission line board 7 and the resonators 1a, 1b.

Conductive pins 22 were used to connect the inner conductors 3a, 3b, 3d, and 3e of ld and le.

Conductor patterns 18a, 18b and electrode patterns 19a, 119e, 20a, 20 forming input/output capacitors are provided on the surface of the sub-transmission line board 7 that does not face the open end surface A.
e is formed. Further, the conductor patterns 18a, 18
Through holes 21 are located at locations corresponding to e, 19a, and 19e.
... is formed.

Such sub-transmission line substrates 7 are arranged in parallel on the open end surface A with a predetermined gap, for example, a gap of 0.5 mm or more.

The conductive member 22 preferably has a cylindrical shape, and has through holes 2a, 2
The conductor is made of a metal such as hard copper, and includes a stand-up portion 22b that forms a gap with a portion 22a that is inserted into the holes 22b, 2d, and 2e, and a portion 22c that is inserted into the through hole 21 of the sub-transmission line board 7. Further, the surface of the insulator may be coated with a conductor.

The through-hole insertion portion 22a accommodates the resonators 1a, 1b, lc...
The shape of the stand-up portion 22b is substantially the same as that of the through-holes 2a, 2b, etc., or the shape is slightly smaller to allow insertion.
, 2b .
c has a shape that is substantially the same as the shape of the through holes 21 of the sub-transmission line board 7, or a shape that is slightly smaller to allow insertion.

Electrical and mechanical joining methods include, for example, through-hole insertion portion 2
Cream solder is applied to 2a and the through-hole insertion portion 22C, and they are joined together in a reflow oven.

Further, bonding using wire solder is also possible.

According to the embodiment described above, the sub-transmission line board 7 is connected to the conductive member 22.
A predetermined gap is formed by the stand-up portion 22b, and the dielectric filter is arranged parallel to the open end surface A, resulting in a small and low-profile dielectric filter as a whole. Further, since the conductor patterns 18a and 18b of the sub-transmission line are formed on the entire surface of the substrate 7 away from the open end surface A, the conductor patterns 18a and 18b and the inner conductors 3a and 3b of the resonators 1a11b11C... % 3 c... can be prevented from occurring, and highly reliable transmission characteristics can be achieved.

Further, by using the conductive member 22, the conductor patterns 18a, 18b and the corresponding resonators 1b, ld are reliably connected, and even more reliable transmission characteristics are achieved.

In the above-mentioned embodiment, a coupling groove is formed by removing a part of the dielectric block from the side surface portions that are connected to each other, but the coupling groove is formed only for one of the resonators that are connected to each other, and the coupling groove is formed for the other resonator. It is also possible to use a resonator in which a part of the outer conductor is removed as in the conventional case.

[Effects of the present invention]

As detailed above, according to the first invention, an inner conductor is provided on the inner surface of the through hole of the dielectric block, and an outer conductor is provided on the outer surface of the dielectric block excluding the open surface where the through hole is formed. A coupling groove is formed in the side surface of the dielectric resonator in a direction perpendicular to the through hole, and three or more resonators are arranged in series so that the side surfaces on which the coupling groove is formed are in contact with each other, and the open surface side Since the substrate on which the electrode pattern of the sub-transmission line connected to the inner conductor of any two resonators is formed is placed on the , the coupling capacitance component of each resonator and the sub-transmission line substrate are separate. Since they do not adversely affect each other, the coupling degree of each resonator is stabilized, and the transmission characteristics of the sub-transmission line are also stabilized, stable polarization, that is, attenuation at a predetermined frequency is achieved.

Further, in the second invention, that is, the first invention, since the electrode pattern of the sub-transmission line and the inner conductor of the resonator are connected by the conductor pin, the sub-transmission line board is surely placed on the open end surface of the resonator. The filters are arranged substantially in parallel, resulting in a small, low-profile polarized dielectric filter as a whole. In addition, since the conductor pattern of the sub-transmission line is formed on the entire surface of the board that does not face the open end surface, unnecessary capacitance can be prevented from occurring.
Reliable transmission characteristics are achieved.

Further, by using the conductive pin, the conductive pattern and the corresponding resonator are reliably connected, and even more reliable transmission characteristics are achieved.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of the dielectric filter of the present invention,
FIG. 2 is an exploded perspective view of another embodiment of the dielectric filter of the present invention. FIG. 3 is an exploded perspective view showing the structure of a conventional dielectric filter.

Claims (2)

[Claims] (1) An inner conductor is provided on the inner surface of a through hole in a dielectric block, and an outer conductor is provided on the outer surface of the dielectric block except for the open surface where the through hole is formed.The side surface of the dielectric resonator is perpendicular to the through hole. a sub-transmission line in which a coupling groove is formed in the direction of A dielectric filter characterized by disposing a substrate on which an electrode pattern is formed. (2) A through hole is formed in the electrode pattern portion of the substrate on which the sub-transmission line electrode pattern is formed, and the electrode pattern and the inner conductor of the arbitrary resonator are connected by a conductor pin. The dielectric filter according to claim 1.