JPH036101A - Dielectric filter - Google Patents

Abstract

PURPOSE:To miniaturize a device as an input/output terminal by providing one or more through-holes on a rectangular parallelopiped dielectric, applying metallic films on the surfaces of five planes except for one plane where the through-holes are provided and the inner planes of the through-holes, and patternizing the metallic films on a confronting plane in land shape. CONSTITUTION:One or more through-holes 21 are formed at a rectangular parallelopiped block consisting of a dielectric. The metallic films 22 are applied on the surfaces of the five planes except for the plane where the through-holes 21 are formed and the inner planes of the through-holes 21. Land shape patterns 23 and 24 are formed by eliminating part of the metallic films 22. The patterns 23 and 24 are set as electrodes of a capacitor, and the capacitor formed between the metallic films 22 of the through-holes 21 is used as a coupling capacitor, and also, the patterns 23 and 24 are used as the input/output terminals.

Description

DETAILED DESCRIPTION OF THE INVENTION (Summary) Regarding a dielectric filter used in a wireless device for a car phone in the 1Z band, for example, several hundred M, the purpose is to make it more compact and have a structure that can be surface mounted. At least one through hole is provided in a rectangular parallelepiped block made of a dielectric material, and a metal coating is applied to five surfaces excluding one of the surfaces with the through hole and the inner surface of the through hole, A part of the metal coating applied to the surfaces of a pair of opposing surfaces is removed to form an island pattern, and the island pattern is configured to serve as an input terminal and an output terminal.

[Industrial application field]

TECHNICAL FIELD The present invention relates to a dielectric filter used in, for example, radio equipment for automobile telephones in the several hundred MHz band.

In recent years, there has been a demand for miniaturization of mobile radio devices used in car telephones and the like, so small semi-coaxial dielectric filters using dielectrics with high dielectric constants have been used.

However, components other than the dielectric filter can be directly connected to the patterns on the printed board without making holes in the printed board. In other words, they tend to be replaced by surface-mountable, yet ultra-small chip components.

This filter also needs to be made smaller and have a structure that can be surface mounted.

[Conventional technology]

FIG. 6 is a configuration diagram of a conventional example, FIG. 6(a) is a perspective view of the conventional example, and FIG.

FIG. 7 is an explanatory diagram of the implementation of FIG. 5, where FIG. 7(a) is a front perspective view of the printed board, and FIG. 7 (with) is a back perspective view of the printed board.

First, as shown in FIG. 6(b), one, for example, two through holes 12.
13 will be provided.

Then, a metal coating is applied to the four side surfaces and top surfaces of this rectangular parallelepiped block 11 except for the lower surface B, and to the inner surfaces of the through holes 12.13, and input terminals 16 are provided to the openings on the lower surface B of the two through holes 12.13. Coupling capacitor with 15.
Two coupling capacitors 17 with output terminals 18 are attached, for example, by soldering. Note that the hatched area in the figure shows the metal coating, and the two-pointed area shows the dielectric part.

In order to ensure that the metal coating applied to the four sides is grounded, one rectangular parallelepiped block is inserted into the metal case 14 as shown in FIG. 6(a), and this metal coating and the metal case 14 are
7(a) after soldering.

As shown in (b), the metal case 14 is soldered to the ground surface on the back of the printed board, and the input/output terminals are soldered to the input and output lines, respectively.

Note that a resonator is constituted by the through holes 12 and 13 in FIG. 6, etc., and the resonant frequency is a frequency at which the length of the through hole is λ/4. Further, since the lower surface B is an open end and the upper surface is a short-circuited end, the coupling capacitor is attached to the portion where the electric field is maximum.

[Problem to be solved by the invention]

Here, in order to use a dielectric material with a high dielectric constant, the resonator itself is miniaturized. However, in order to ensure that the metal coating is grounded, it must be inserted into a metal case and input/output terminals must be attached, so it cannot be miniaturized as a dielectric filter.

Further, in order to mount this dielectric filter, there are two problems: holes must be made to attach the legs 141 of the metal case and the input/output terminals 16, 18, and surface mounting is not possible.

An object of the present invention is to provide a structure in which a dielectric filter is more compact and can be surface mounted.

[Means to solve problems]

FIG. 1 shows a basic configuration diagram of the present invention.

Reference numeral 21 indicates at least one through hole in a rectangular parallelepiped block made of a dielectric material, and reference numeral 22 indicates at least one through hole on the surface with the through hole, and 23
．． 24 is an island pattern formed by removing a part of the metal coating applied to the surfaces of a pair of opposing surfaces.

[Effect]

Generally, a dielectric filter applies electric field coupling to the open end of a resonator using a coupling capacitor, as shown in FIG. 6(b), to apply a signal to the resonator or to take out a signal from the resonator.

However, the present invention uses a coupling capacitor of 15°17
Instead, as shown in FIG. 1, part of the metal coating 22 is removed to form island patterns 23 and 24, and this island pattern is used as the electrode of the capacitor. The capacitor formed with the metal film is used as a coupling capacitor, and this pattern itself is used as an input/output terminal.

Now, the filter must be able to design the passband width arbitrarily, but in that case, the area of the island pattern is changed in the design. That is, in the case of a narrow band filter, the area of the island pattern is made small in order to weaken the coupling, and in the case of a wide band filter, the area of the island pattern is made large.

At this time, the position of the island pattern in the longitudinal direction of the dielectric block may be arbitrary, and if it is provided near the open end, the second
As shown in the figure, since the electric field strength is high, the coupling becomes strong, resulting in a broadband filter.

However, when a narrowband filter is required, the coupling becomes stronger at the open end, so the area of the island pattern can be made smaller, but the area can be made smaller (this will reduce the dimensional accuracy or adhesion strength of the island pattern. , it is sufficient to form an island pattern with a relatively large area on the side closer to the short-circuited end on the opposite side.

By directly connecting the island pattern to the input/output line formed on the printed board, and the metal coating to the ground pattern on the printed board, a reliable grounding can be achieved, eliminating the need for the aforementioned metal case and input/output terminals. becomes.

For this reason, it has become more compact as a dielectric filter.

Moreover, the structure allows surface mounting.

〔Example〕

3 is a configuration diagram of an embodiment of the present invention, FIG. 3(a) is a perspective view, FIG. 3(c) is a rear perspective view, FIG. 4 is an explanatory diagram of the implementation of FIG. 3, and FIG. shows an implementation diagram of a 5-section bandpass filter.

Figure 3 shows a one section bandpass filter.
As shown in the figure, a through hole 21 is provided in the rectangular parallelepiped block 2, and a metal coating is applied to three surfaces of the rectangular parallelepiped block other than the B surface and the inner surface of the through hole 21. Then, a part of the metal coating applied to the opposing 0 and 0 sides is removed to form a pair of island patterns 23 and 24, but the forming positions and the area of the island patterns are as described above. This can be decided based on accuracy, etc.

In addition, to adjust the resonance frequency, it is necessary to shorten the length of the resonator by cutting the 8th side of the metal coating on the inner surface of the through hole, but unlike the conventional example shown in Figure 6, this part Adjustment is easy because there is no coupling capacitor.

Now, in order to implement this one-section bandpass filter, as shown in Figure 4, a stripline that will serve as the ground plane and the input/output line is formed on the printed board, and the island pattern of the bandpass filter and the strip It is surface mounted by soldering the part of the metal coating that contacts the line and ground plane.

Further, as shown in FIG. 5, a five-section bandpass filter can also be surface-mounted in the same manner as described above. still,
21 indicates a rectangular parallelepiped block.

That is, the dielectric filter can be made smaller and can be surface mounted.

21 is a through hole; 22 is a metal coating; 23 and 24 show island patterns.

〔Effect of the invention〕

As described above in detail, the present invention has the advantage of being more compact and capable of surface mounting.

[Brief explanation of drawings]

Fig. 1 is a diagram of the principle configuration of the present invention, Fig. 2 is an explanatory diagram of the operation of Fig. 1, Fig. 3 is a diagram of the configuration of an embodiment of the present invention, Fig. 4 is an explanatory diagram of implementation of Fig. 3, and Fig. 5 The figure shows an implementation explanatory diagram of a 5-section bandpass filter, FIG. 6 shows a configuration diagram of a conventional example, and FIG. 7 shows an implementation explanatory diagram of FIG. 5. In the figure, 2 is a rectangular parallelepiped block, 22 3 51 Concave Electric Power Agency “Blind Love August Diagram”

Claims (1)

[Claims] At least one cuboid block (2) made of dielectric material
At least one through hole (21) is provided, and a metal coating (22) is applied to five surfaces excluding one of the surfaces with the through hole and the inner surface of the through hole. A part of the metal coating applied to the surface of the opposing surface is removed to form an island pattern (23, 2).
4), and the island pattern is used as an input terminal and an output terminal.