JPS63135001A - Dielectric filter - Google Patents

Abstract

PURPOSE:To facilitate the assembling, adjustment and connection or the like by using an inner conductor inserted into a through hole as one electrode and forming a capacitance in opposition to a flat plane formed to an upper end of an input/output terminal pin via an insulation sheet such as a 'Mylar(R)' film. CONSTITUTION:The insulation sheet 17 such as a 'Mylar(R) film is arranged between an exposed face of an inner conductor 11 and an input/output terminal pin 16 prior to the containment of a dielectric block to a case 15. Thus, the inner conductor 11 and the input/output terminal pin 16 are opposed via the insulation sheet 17. That is, the two conductors are opposed to each other while chipping a dielectric and the part acts like a kind of capacitor. The capacitor is utilized as a coupling capacitor of the input/output of the dielectric filter. Since the opposed area of the flat parts of the inner conductor 11 and the input/output terminal pin 16 is constant, the capacitance depends on the thickness and the dielectric of the insulation sheet 17. Thus, the input/output coupling capacitance is set optionally by varying the thickness of the insulation sheet 17.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to the structure of a dielectric filter, and particularly relates to a structure for obtaining input/output coupling capacitance of a dielectric filter using dielectric blocks. be.

[Prior art]

Various types of dielectric filters are used that use a plurality of coaxial dielectric resonators and couple them through capacitance. Furthermore, devices in which a dielectric resonator is integrated into a dielectric block are also being used as compact filters in various fields.

This filter is constructed using electromagnetic coupling and capacitive coupling, and an inner conductor is formed in a through hole of a dielectric block, and an outer conductor is formed on the surface.

It is necessary to obtain an input/output coupling capacitance between the input terminal, the output terminal, and the inner conductor, and various structures for this purpose have been proposed. Japanese Utility Model Application Publication No. 58-54102 discloses the use of conductive wires coated with dielectric material as input/output pins. Another method is to fill a hole formed in a dielectric block with a conductor to form a capacitance with the inner conductor, as disclosed in Japanese Utility Model Application No. 60-98902.

A dielectric filter including these dielectric blocks and input/output means is housed in a case, and the outer conductor is connected to a ground terminal for assembly. At that time, the dielectric block may be processed to adjust the resonance frequency.

A dielectric filter using such a dielectric block is required to be easy to assemble and to have a small number of parts. Furthermore, it is desirable that the structure of each individual component be simple and low cost.

Furthermore, since it is often necessary to polish or remove the surface of the dielectric block in order to obtain desired filter characteristics, it is better that the surface of the dielectric block be easier to process. It is preferable that it can be easily processed not only before assembly but also after assembly.

None of the conventional dielectric filters satisfies all of these requirements, and many of them have one or the other problem.

〔the purpose〕

The present invention is characterized by solving the above-mentioned problems and obtaining a dielectric filter that is easy to assemble, adjust, connect, etc. In particular, the input/output coupling structure is improved, and the number of parts is reduced, The purpose is to facilitate capacity adjustment.

[Means for solving problems]

The present invention uses an inner conductor filled in a through hole as one electrode, and forms a capacitor by facing a flat surface formed at the upper end of an input/output terminal pin through an insulating sheet such as Mylar film. This achieves the above objectives.

That is, in a dielectric filter that obtains capacitive coupling between an inner conductor formed in a through hole of a dielectric block and an input/output terminal pin, the inner conductor is filled with a conductor at least on the open end side of the through hole, The device is characterized in that the ends of the input/output terminal pins are formed flat, and the inner conductor and the input/output terminal pins are arranged facing each other with an insulating film interposed therebetween to obtain a capacitance.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front sectional view showing an embodiment of the present invention.

In this case, the dielectric resonator 10 made of a dielectric block is one in which three elements are integrated, and an inner conductor 11 is formed in two through holes, and a coupling hole 12 is provided in the center. An outer conductor 13 is formed on the surface of this dielectric block except for the bottom surface. The bottom surface, that is, the open end side of the inner conductor 11 is filled with a conductor. The entire through hole may be filled with the conductor, but it is sufficient that at least the bottom side is closed. Even in that case, it is necessary to form a conductor film on the entire surface inside the through hole.

The dielectric block with conductors formed in this way is case 1.
It is stored in 5. The case 15 is made of a thermosetting resin or a heat-resistant resin, and combines a box body and a lid part. Input/output terminal pins 16 are implanted in the bottom of the box. The upper end of the input/output terminal pin 16 is flat, and is engaged with the case 15 by this portion, and is disposed so as to face the inner conductor 11 of the dielectric block. Therefore, it is desirable that this flat portion has a size equal to or larger than the diameter of the through hole.

Before storing the dielectric block in the case 15, the inner conductor 1
An insulating sheet 17 such as a Mylar film is placed between the exposed surface of the pin 1 and the input/output terminal pin 16. This allows the second
As shown in the figure, the inner conductor 11 and the input/output terminal pin 16 face each other with an insulating sheet 17 in between.

The two conductors face each other with a dielectric material in between, and this part becomes a kind of capacitor. This capacitor is used as a dielectric and a coupling capacitance between the input and output of the filter.

Since the facing area of the inner conductor 11 and the flat part of the input/output terminal pin 16 is constant, the capacitance is determined by the thickness of the insulating sheet 17,
It is determined by the dielectric constant. Utilizing this, the input/output coupling capacitance can be set arbitrarily by changing the thickness of the insulating sheet 17.

The thickness of the Mylar film insulation sheet 17 is 0.1 to 0.
．． 4mm, and the inner conductor diameter is 2.5mm, approximately 2
A capacitance of ˜0.5 pF was obtained. This is a sufficient value for the input/output coupling capacitance of a normal dielectric filter.

A window 18 is formed on the side surface of the case 15. This is for adjusting the resonant frequency of the dielectric resonator by cutting the outer conductor 13 of the dielectric block.

That is, when the resonance frequency needs to be adjusted after the dielectric block is housed in the case 15, the outer conductor 15 can be cut off through the window 18 using a router or the like. To adjust the resonance frequency, it is possible to increase the frequency by carving the side surface and lower the frequency by carving the top surface. Therefore, this window 18 can be used when increasing the frequency. If the frequency is to be lowered, processing may be performed before covering the case 15 with the lid.

In addition to the input/output terminal pins 16, a ground pin 19 is also implanted in the case 15. A hole (not shown) is provided in the case 15 where the upper end portion of the earth pin 19 is located. The outer conductor of the dielectric block and the ground pin 19 are soldered using the hole, thereby making it possible to easily and reliably connect the outer conductor to the ground pin.

Although the embodiment has been described using a resin case, substantially the same structure can be obtained even when a metal case is used. In that case, it is necessary to insulate the input/output pins and the case. Further, the shape of the flat portion of the input/output terminal pin is not limited to a circle, but may be a square or a rectangle. 'Before storing the dielectric block in the case, it is usually polished for frequency adjustment. This is done by polishing the surface of the open end example. Therefore,
If the dielectric block filled with the conductor of the inner conductor 11 is polished for frequency adjustment, the conductor surface can be made flat at the same time. In this respect, it is more advantageous than forming an electrode on the open end surface. The conductor of the inner conductor is formed by press-fitting a metal rod, filling with solder, or injecting a conductive paste, a thick film conductor with a glass lift, etc., and stable flatness can be obtained by the above-mentioned polishing process.

〔effect〕

According to the present invention, the input/output coupling capacitance of a dielectric filter can be obtained with an extremely simple structure. That is, no special parts are required, and only a slight change in the shape of the pin is sufficient.

Furthermore, the capacitance can be changed arbitrarily simply by changing the thickness of the insulating sheet. Therefore, it is possible to prepare several types of sheets and select and use them depending on the variation in characteristics.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view showing an embodiment of the present invention, and FIG. 2 is a partially enlarged view of FIG. 1. 10: Dielectric resonator 11: Inner conductor 13: Outer conductor 15
: Case 16: Input/output terminal pin 17: Mylar film

Claims (1)

[Claims] In a dielectric filter that obtains capacitive coupling between an inner conductor formed in a through hole of a dielectric block and an input/output terminal pin, the inner conductor is filled with a conductor at least on the open end side of the through hole, and 1. A dielectric filter characterized in that the end of the output terminal pin is formed flat, and the inner conductor and the input/output terminal pin are arranged to face each other with an insulating film interposed therebetween to obtain a capacitance.