JPH05308205A - Dielectric filter - Google Patents

Abstract

PURPOSE:To provide the dielectric filter with simple structure and whose frequency response is easily adjusted. CONSTITUTION:A 1st dielectric board 10 in which input/output conductors 11a, 11b are formed in parallel and connection conductors 12a, 12b causing input output capacitors C1, C2 opposite to both the input/output conductors 11a, 11b are formed to an outer face, and a 2nd dielectric board 20 in which a capacitor pattern causing a coupling capacitance C3 in inter-stage coupling of pattern conductors 22a, 22b corresponding to dielectric coaxial resonators 2a, 2b is caused to an inner face and an earth conductor 23 to cover the pattern conductors 22a, 22b are formed to the outer face to cause stray capacitors C4, C5 are overlapped to one side face of the dielectric coaxial resonators 2a, 2b and the pattern conductors 22a, 22b and connection conductors 12a, 12b are respectively connected electrically to inner conduction films 4a, 4b of the dielectric coaxial resonators 2a, 2b and the input output conductors 11a, 11b are connected to external electric lines.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter having a plurality of dielectric coaxial resonators arranged in parallel.

[0002]

2. Description of the Related Art A plurality of dielectric coaxial resonators each having a through hole in the axial direction, an inner conductive film formed on the inner peripheral surface of the through hole, and an outer conductive film formed on the outer peripheral surface excluding the front surface. A dielectric filter arranged in parallel is disclosed in JP-A-3-136502. In such a configuration, each resonator is covered with a printed circuit board, a plurality of pattern conductors are interstage-coupled on the board to form a capacitive pattern to generate a coupling capacitance, and each pattern conductor is provided with a coaxial resonance. It is connected to the inner conductive film of the child. A capacitor is externally connected to the inner conductive films of the coaxial resonators at both outermost positions connected to the input / output terminals to secure input / output capacitance, and the frequency response is adjusted and the resonator length is adjusted. In some cases, stray capacitance is formed for the purpose of shortening, but in that case as well, a separate capacitor is connected and secured between the inner conductive film of each coaxial resonator and the ground terminal.

[0003]

In the above-mentioned structure, an external member is required to generate each capacitance, which complicates the structure and increases the size. Further, there is a problem in that the capacitance cannot be set and adjusted after the filter is constructed. The present invention is intended to eliminate the problems of the conventional configuration.

[0004]

According to the present invention, a through hole is provided in the axial direction, an inner conductive film is formed on the inner peripheral surface of the through hole, and the inner conductive film is fitted into the through hole to electrically connect to the inner conductive film. A plurality of dielectric coaxial resonators in which the connecting terminals to be electrically connected are projected from the front surface and the outer conductive film is formed on the outer peripheral surface excluding the front surface, and the dielectric coaxial resonators at both outermost positions are arranged on the inner surface side. Two input / output conductors corresponding to the input / output conductors are formed side by side, connection conductors that face both the input / output conductors and generate an input / output capacitance are formed side by side, and a fitting insertion hole into which each connecting terminal is inserted is formed. Is disposed so as to cover the front surface of the coaxial resonator, and the connecting conductor is electrically connected to the inner conductive film by the connecting terminal inserted into the insertion hole, and the inner surface is formed. On the side, a plurality of pattern conductors corresponding to each dielectric coaxial resonator should be interstage-coupled to generate a coupling capacitance. A second dielectric substrate formed with a capacitance pattern, an earth conductor is formed on the outside so as to cover the pattern conductors to generate a stray capacitance, and a fitting insertion hole into which the connecting terminal is fitted is formed, The pattern conductors at both outermost positions are arranged so as to be superposed on the first dielectric substrate so as to be electrically joined to the connection conductors of the first dielectric substrate, and each pattern conductor is inserted into the insertion hole. It is characterized in that they are electrically connected to the inner conductive films of the respective dielectric coaxial resonators through the connected connecting terminals.

[0005]

In the above-described structure, the coaxial resonators at both outermost positions have their inner conductive films electrically connected to the connecting conductors on the outer side of the first dielectric substrate by connecting terminals. Between the connecting conductor and the facing input / output conductor via the substrate,
Input / output capacitance is generated and connected to the input / output terminals, respectively. On the other hand, the inner conductive film of each dielectric coaxial resonator is connected to the respective pattern conductors, and a coupling capacitance is generated between the inner conductive films due to interstage coupling of the pattern conductors. Furthermore, each pattern conductor faces the ground conductor through the dielectric substrate, and a stray capacitance is generated between them to be grounded.

When a dielectric filter is composed of two dielectric coaxial resonators, the outermost position means the two. Further, the pattern conductor may be connected to the connecting terminal via the connecting conductor and thereby electrically connected to the inner conductive film.

In such a structure, the resonator length is shortened by forming the stray capacitance, and after the respective resonators are assembled,
Since the ground conductor is exposed to the outside, stray capacitance can be reduced and the frequency can be increased by removing the ground conductor. Alternatively, by adding a conductor, the stray capacitance can be similarly increased and the frequency can be lowered. Furthermore, the degree of coupling can be adjusted by shaving the ground conductor on the back side of the coupling portion of the pattern conductor.

[0008]

1 to 4 show two dielectric coaxial resonators 2a,
An example in which the dielectric filter 1 is composed of 2b will be shown. Here, the dielectric coaxial resonators 2a and 2b are in the shape of a rectangular parallelepiped made of a titanium oxide ceramic dielectric, and through holes 3 and 3 are formed in the center thereof in the axial direction. Inner conductive films 4a and 4b are formed on the inner peripheral surface of the above, and outer conductive films 5 are formed on the peripheral surfaces of the dielectric coaxial resonators 2a and 2b except the front surface. Further, the through holes 3 and 3 are fitted with metal connecting terminals 6 and 6 which are tightly fitted at their end positions to ensure electrical connection with the inner conductive films 4a and 4b, and their small diameter connections. The end 7 is projected outward from the front surfaces of the dielectric coaxial resonators 2a and 2b.

Then, each of the dielectric coaxial resonators 2a, 2a
A first dielectric substrate 10 and a second dielectric substrate 20 are arranged in a superposed manner on the front part of b. The dielectric substrates 10 and 20 are made of a ceramic dielectric.

As shown in FIG. 2A, the first dielectric substrate 10 is arranged on its inner surface side by side so as to be opposed to the dielectric coaxial resonators 2a and 2b, respectively.
a and 11b are formed. Further, as shown by B in FIG. 2, connection conductors 12a and 12b are formed on the outer surface of the input / output conductors 11a and 11b so as to face each other.
11b and fitting conductors 13a and 13 which penetrate the connecting conductors 12a and 12b and into which the small diameter connecting ends 7 of the connecting terminals 6 and 6 are inserted.
b is pierced. Further, on the inner surface side of the first dielectric substrate 10, the input / output conductors 11a, 1a are formed at the peripheral portions of the insertion holes 13a, 13b.
By removing the conductive layer of 1b, the small-diameter connecting end 7 becomes the input / output conductor 1
1a and 11b are not electrically connected, and on the outer side of the first dielectric substrate 10, the small diameter connection end 7 and the connection conductors 12a and 12b are electrically connected. Further, elongated through holes 14 for connection are formed on the left and right at positions not in contact with the connection conductors 12a, 12b.

The second dielectric substrate 20 has comb-shaped pattern conductors 22a and 22b on its inner surface as shown in FIG. 3A.
Are arranged so as to face the connection conductors 12a and 12b by being superposed on the first dielectric substrate 10, and the comb patterns are interlocked with each other so that the capacitance pattern 2 is formed.
1 is formed. Further, on the outer surface of the second dielectric substrate 20, a ground conductor 23 is formed so as to face the pattern conductors 22a and 22b continuously in the left and right direction as shown by B in FIG. And each pattern conductor 22a, 22b
The fitting insertion holes 24a and 24b are provided so as to penetrate therethrough, and the connection terminals 6 and 6 connected to the inner conductive films 4a and 4b are inserted into the fitting insertion holes 24a and 24b. Incidentally, the fitting holes 24a, 24b
The conductive layer of the ground conductor 23 is removed at the peripheral portion so that the connecting terminals 6 and 6 are not electrically connected to the ground conductor 23. On the other hand, the pattern conductors 22a and 22b are connected to the connection terminals 6 and 6 (inner conductive films 4a and 4b) via the connection conductors 12a and 12b. The pattern conductors 22a and 22b may be directly connected to the connecting terminals 6 and 6. Further, elongated through holes 25, 25 for connection are formed on the left and right so as to be aligned with the through holes 14, 14 in the front and back so as not to come into contact with the pattern conductors 22a, 22b.

Then, the input / output conductors 11a and 11b
Terminal plates 30a, 30 that are surface-bonded to the
The pull-out legs 31 and 31 of b (see FIG. 1) are attached to the through-hole 1
4, 14 and the through-holes 25, 25 so that the tips of the lead-outs 3 are inserted into the through-holes of the printed circuit board so as to project the tips thereof.
The input / output conductors 11a and 11b are connected to the input-side external electric path and the output-side external electric path by 1, 31.
The ground conductor 23 is grounded via a case or the like.

Thus, the dielectric substrates 10 and 20 are overlapped with each other to form the inner conductive film 4a of the dielectric coaxial resonators 2a and 2b.
The input / output 4b is electrically connected to the connecting conductors 12a and 12b outside the first dielectric substrate 10 by connecting terminals 6 and 6 and faces the connecting conductors 12a and 12b through the dielectric substrate 10. Input / output capacitors C ₁ and C ₂ are generated between the conductors 11a and 11b as shown in the equivalent circuit of FIG. 5, and are connected to the external input / output terminals by the terminal plate 30.

The connecting conductors 12a and 12b are connected to the pattern conductors 22a and 22b, respectively, and a coupling capacitance C ₃ is generated by the interstage coupling of the pattern conductors 22a and 22b. Further, each pattern conductors 22a, 22b are opposed to the earth conductor 23 through the second dielectric substrate 20, caused the stray capacitance C _4, C ₅ therebetween are grounded.

In the above-mentioned embodiment, the dielectric filter 1 is composed of the two dielectric coaxial resonators 2a and 2b, but three or more of them can be arranged in parallel. In this case, The input / output conductor 11a of the first dielectric substrate 10,
11b is formed corresponding to the outermost dielectric coaxial resonator,
Connection conductors 12a, 12b facing the input / output conductors 11a, 11b on the outer surface side to generate input / output capacitance are arranged in parallel, and the number of dielectric coaxial resonators is provided on the inner surface side of the second dielectric substrate 20. And a plurality of pattern conductors equal to each other are coupled between the stages to generate a plurality of coupling capacitors, and the ground conductor 23 is provided outside the second dielectric substrate 20 so as to cover the pattern conductors.
Should be formed.

[0016]

As described above, according to the present invention, the dielectric substrate 1
I / O capacitances C ₁ and C
₂ , the coupling capacitance C ₃ and the stray capacitances C ₄ and C ₅ can be arbitrarily set, and the external configuration of the capacitor is not required, and the configuration can be simplified. Further, by forming the stray capacitance, the resonator length can be shortened, and after the assembly, the coupling capacitance C ₃ and the stray capacitances C ₄ , C ₅ can be easily adjusted by deleting or adding the ground conductor 23. Further, there is an excellent effect that the frequency response can be made appropriate.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a dielectric filter 1.

FIG. 2 shows a first dielectric substrate 10, where A is the inner surface and B is the inner surface.
Indicates the outer surface.

FIG. 3 shows a second dielectric substrate 20, where A is the inner surface and B is the inner surface.
Indicates the outer surface.

FIG. 4 is a vertical sectional side view.

FIG. 5 is an equivalent circuit diagram.

[Explanation of symbols]

1 Dielectric Filter 2a, 2b Dielectric Coaxial Resonator 3,3 Through Hole 4a, 4b Inner Conductive Film 6,6 Connection Terminal 10 First Dielectric Substrate 11a, 11b Input / Output Conductor 12a, 12b Connection Conductor 14, 14 Penetration Hole 20 Second dielectric substrate 21 Capacitance pattern 22a, 22b Pattern conductor 23 Ground conductor 24a, 24b Fitting hole 25, 25 Through hole C ₁ , C ₂ Input / output capacitance C ₃ Coupling capacitance C ₄ Stray capacitance

Claims (1)

[Claims] 1. A front surface of a connecting terminal, which has a through hole in the axial direction, an inner conductive film is formed on an inner peripheral surface of the through hole, and which is fitted in the through hole and electrically connected to the inner conductive film. Two dielectric input / output conductors corresponding to the dielectric coaxial resonators at both outermost positions are provided on the inner surface side, with a plurality of dielectric coaxial resonators juxtaposed from each other and having outer conductive films formed on the outer peripheral surface excluding the front surface. A first dielectric substrate in which connecting conductors that face both input / output conductors and generate an input / output capacitance are formed in parallel on the outer surface side, and a fitting insertion hole into which each connecting terminal is fitted is formed. , Disposed so as to cover the front surface of the coaxial resonator,
The connection conductor is electrically connected to the inner conductive film by the connection terminal inserted in the insertion hole, and a plurality of pattern conductors corresponding to the respective dielectric coaxial resonators are interstage-coupled on the inner surface side to form a coupling capacitance. A second dielectric formed by forming a generated capacitance pattern, forming an earth conductor on the outside so as to cover each of the pattern conductors to generate stray capacitance, and forming a fitting insertion hole into which the connecting terminal is fitted. The body substrate is superposed on the first dielectric substrate, and the pattern conductors at both outermost positions are arranged so as to be electrically joined to the connection conductors of the first dielectric substrate, and the pattern conductors are fitted together. A dielectric filter characterized in that it is electrically connected to an inner conductive film of each dielectric coaxial resonator through a connecting terminal inserted in an insertion hole.