JPH0774511A - Stripline filter - Google Patents

Abstract

PURPOSE:To miniaturize the whole filter by arranging an electric shield means between plural strip conductors and connecting the shield means with an earth pattern via a via hole formed in a dielectric. CONSTITUTION:A via hole 25 is formed by making a lower part conductor 2 and an upper part conductor 4 penetrate between strip conductors 5 and 6. Within the via hole 25, a conducting bar 26 is inserted. The via hole 25 and the conducting bar 26 are composed of groups 29 and 30 arranged at a constant space and the conducting bar 26 is connected with earth patterns 1 and 3, respectively. Thus, the conducting bar 26 performs its electric shield role between the conductors 5 and 6. Therefore, the coupling distance ID between the conductors 5 and 6 can be reduced, a coupling width IC can be increased and the whole filter can be miniaturized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stripline filter using a stripline as a filter element in the microwave or millimeter wave band, and more particularly, it can reduce the area occupied by a filter pattern to downsize the entire filter. A stripline filter that can be used.

[0002]

2. Description of the Related Art Generally, as a microwave or millimeter wave band filter element, a strip line filter formed by combining distributed constant circuits such as strip lines is known.

As a conventional example, FIG. 4 shows a three-stage interdigital stripline filter using a conductive pattern of a quarter-wave resonator. Here, FIG. 4A is a partially transparent perspective view of the stripline filter.
4B is a plan view, FIG. 4C is a left side view, FIG. 4D is a right side view, FIG. 4E is a front view, and FIG. 4F is a bottom view.
FIG. 4G is a sectional view taken along the line AA ′ of FIG. In addition, the partially transparent perspective view of FIG. 4A shows the upper dielectric 4 and the second ground pattern 3 which will be described later.

As shown in FIG. 4, this stripline filter has a first dielectric pattern 1 between a lower dielectric 2 having a first ground pattern 1 on its lower surface and an upper dielectric 4 having a second ground pattern 3 on its upper surface. The structure is such that a quarter-wave resonator filter pattern 8 composed of the first and second strip-shaped conductors 5 and 6 is sandwiched. That is, the lower dielectric 2 and the upper dielectric 4 form a rectangular dielectric substrate, and the filter pattern 8 is formed in the dielectric substrate.

The first and second feeding patterns 11 and 12 are connected to the respective side portions of the first and second strip-shaped conductors 5 and 6 via taps 9 and 10. And each tip 1 of the second power supply patterns 11 and 12
3 and 14 reach the side surfaces 15 and 16 of the dielectric substrate, and are provided along the side surfaces 15 and 16 on the respective tip portions 13 and 14 of the first and second power feeding patterns 11 and 12, respectively. The input terminal 17 and the output terminal 18 are connected to each other. The input terminal 17 and the output terminal 18
Extends below the connection points with the tip portions 13 and 14 and reaches the lower surface of the lower dielectric 2, but as shown in FIG. 4 (f), does not connect with the first ground pattern 1. It has become.

The first and second strip-shaped conductors 5 and 6 are connected to the first and second ground patterns 1 and 3 via the first and second connecting members 19 and 20, respectively. ing. Here, the center frequency of the stripline filter as described above is the first frequency of the 1/4 resonator filter pattern 8.
And the lengths 1A and 1B of the second strip conductors 5 and 6 and the relative permittivity of the dielectric substrate on which the pattern 8 is arranged.

The band width of this strip line filter is generally parallel to the first strip-shaped conductors 5 described above.
And the second strip-shaped conductor 6 are coupled to each other. That is, the larger the portion 1C (hereinafter, the coupling width) where the first strip-shaped conductor 5 and the second strip-shaped conductor 6 are overlapped with each other, and the shorter the distance 1D (hereinafter, the coupling distance) between them, the bandwidth. Becomes wider.

Therefore, when an attempt is made to realize a narrow band filter by the above stripline filter,
It is necessary to narrow the coupling width lC and increase the coupling distance lD, and the filter pattern 8 needs a large space in the longitudinal direction E and the lateral direction F of the strip conductors 5 and 6. That is, the conventional stripline filter has a drawback that the area occupied by the filter pattern becomes larger as the band becomes narrower.

[0009]

The present invention has been made in view of the above circumstances, and provides a stripline filter capable of reducing the area occupied by a filter pattern to reduce the size of the entire filter despite a narrow band. The purpose is to

[0010]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a stripline filter having a filter pattern formed of a plurality of strip-shaped conductors in a dielectric substrate having ground patterns on the upper and lower surfaces thereof.
An electric shield means is disposed between the two strip conductors, and the shield means is inserted into the via hole formed in the dielectric between the strip conductors and at least one of the upper and lower ground patterns. It is characterized in that it is composed of connected conductor members.

[0011]

The present invention will be described below based on the illustrated embodiments.

FIG. 1 is a block diagram showing an embodiment of a stripline filter according to the present invention, and FIG.
FIG. 1 is a partially transparent perspective view of a stripline filter.
1B is a plan view, FIG. 1C is a left side view, FIG. 1D is a right side view, FIG. 1E is a front view, and FIG. 1F is a bottom view.
FIG. 1G is a sectional view taken along the line AA ′ of FIG.
The partially transparent perspective view of FIG. 1A shows the upper dielectric 4 and the second ground pattern 3 in a transparent manner.

The stripline filter according to the present invention shown in FIG. 1 is provided with a new electric shield means between the first strip conductor 5 and the second strip conductor 6 in the conventional example shown in FIG. The gist is that the area occupied by the pattern 8 is reduced.

In FIG. 1, the same elements as those in the conventional example shown in FIG. 4 are designated by the same reference numerals.

As shown in FIG. 1, this stripline filter includes a lower dielectric 2 having a first ground pattern 1 on its lower surface and an upper dielectric 4 having a second ground pattern 3 on its upper surface. The structure is such that a quarter-wave resonator filter pattern 8 composed of the first and second strip-shaped conductors 5 and 6 is sandwiched. That is, a rectangular dielectric substrate is formed by the lower dielectric 2 and the dielectric 4, and the filter pattern 8 is formed in the dielectric substrate.

Between the first strip-shaped conductor 5 and the second strip-shaped conductor 6, a plurality of upper and lower lower dielectrics 2 and 4 are provided as an electric shield means so as to be vertically suspended. Cylindrical via hole 25, and the first ground pattern 1 and the second ground pattern 2 inserted in the via hole 25.
And a plurality of conductor rods 26 connected to the ground pattern 3 of FIG. In this embodiment, the plurality of via holes 25 and the conductor rods 26 are arranged in a middle position between the first strip-shaped conductor 5 and the second strip-shaped conductor 6 and are arranged at regular intervals in four first groups 29. And its first group 2
It is composed of four second groups 30 which are arranged at regular intervals at positions separated by a predetermined distance 1E from 9.

Here, the conductor rod 2 in the via hole 25 is
Since 6 is connected to the first and second ground patterns 1 and 3, it has a ground potential, and acts as an electric shield between the first and second strip conductors 5 and 6.
Therefore, during operation, substantially the same effect is obtained by increasing the coupling distance ID between the first strip conductor 5 and the second strip conductor 6 and decreasing the coupling width IC. Therefore, even when an attempt is made to realize a narrow band filter, in this embodiment, as compared with the conventional one, the coupling distance l
D can be greatly reduced and the coupling width lC can be significantly increased. As a result, the filter pattern 8
The area occupied by the filter can be significantly reduced, and the entire filter can be downsized.

The other structure is the same as that of the conventional example shown in FIG. That is, the first and second strip-shaped conductors 5,
6 to each side via taps 9 and 1
Power supply patterns 11 and 12 are connected, and the first
And each tip portion 13 of the second power supply patterns 11 and 12,
14 reaches the side surfaces 15 and 16 of the dielectric substrate, and is provided along the side surfaces 15 and 16 on the respective tip portions 13 and 14 of the first and second power feeding patterns 11 and 12, respectively. The input terminal 17 and the output terminal 18 are connected. The input terminal 17 and the output terminal 18 extend below the connection points with the tip portions 13 and 14 and reach the lower surface of the lower dielectric 2, but as shown in FIG. It is designed not to be connected to the earth pattern 1.

The first and second strip-shaped conductors 5 and 6 are connected to the first and second earth patterns 1 and 3 via the first and second connecting members 19 and 20, respectively. ing.

The via hole 25 and the conductor rod 2 are provided.
The shield effect of 6 is mainly proportional to the numbers of the via holes 25 and the conductor rods 26, although it depends on the sizes of the via holes 25 and the conductor rods 26.

Therefore, as shown in the modification of FIG. 2, if the number of via holes 25 is increased, the first band-shaped conductor 5 and the second band-shaped conductor 6 are formed in the same narrow band as in the embodiment shown in FIG. The coupling width lC can be further increased as compared with the above embodiment.

2A is a plan view of a stripline filter as a modified example, FIG. 2B is a left side view, FIG. 2C is a right side view, and FIG. 2D is a front view. Figure, Figure 2
2E is a bottom view, and FIG. 2F is a sectional view taken along the line AA ′ of FIG.

The size and shape of the via hole 25 and the conductor rod 26 are not limited to those in the above embodiment, but may be elongated long holes and plate shapes as shown in the modification of FIG.

Here, FIG. 3 (a) is a plan view of a stripline filter as a modified example, FIG. 3 (b) is a left side view, FIG. 3 (c) is a right side view, and FIG. 3 (d) is a front view. Figure, Figure 3
3E is a bottom view, and FIG. 3F is a sectional view taken along the line AA ′ of FIG.

In the above-described embodiments and modifications, the case of the filter pattern having the first and second strip-shaped conductors has been described, but three or four.
Needless to say, also in the case of a filter pattern having a strip-shaped conductor, the same effect can be obtained by providing a shield means between the strip-shaped conductors.

In the above embodiment, the interdigital filter pattern is shown, but the present invention can be similarly applied to a combline filter pattern and a general stripline filter, and the same effect can be obtained. .

[0027]

As described above, the present invention has a structure in which via holes and conductor rods are provided as electrical shield means between strip-shaped conductors of a filter pattern of a stripline filter. The occupied area can be reduced to reduce the size of the entire filter.

[Brief description of drawings]

1A and 1B are configuration diagrams showing an embodiment of a stripline filter according to the present invention, FIG. 1A is a partially transparent perspective view of the stripline filter, FIG. 1B is a plan view, and FIG. 1C is a left side view. , (D) is a right side view, (e) is a front view, (f)
Is a bottom view, and (g) is a sectional view taken along the line AA ′ of FIG.

2A and 2B are configuration diagrams showing a modified example of the stripline filter according to the present invention, in which FIG. 2A is a plan view, FIG. 2B is a left side view, FIG. 2C is a right side view, and FIG. 2E is a bottom view, and FIG. 2F is a sectional view taken along the line AA ′ of FIG.

FIG. 3 is a configuration diagram showing a modified example of the stripline filter according to the present invention, in which (a) is a plan view, (b) is a left side view, (c) is a right side view, and (d) is a front view. 3E is a bottom view, and FIG. 3F is a sectional view taken along the line AA ′ of FIG.

FIG. 4 is a configuration diagram of a conventional stripline filter, (a) is a partially transparent perspective view of the stripline filter, (b) is a plan view, (c) is a left side view,
(D) is a right side view, (e) is a front view, (f) is a bottom view,
4G is a sectional view taken along the line AA ′ of FIG.

[Explanation of symbols]

1, 3 ... First and second ground patterns, 2, 4 ... Lower and upper dielectrics, 5, 6 ... First and second strip conductors,
8 ... filter pattern, 9, 10 ... tap,
11, 12 ... First and second power feeding patterns, 13, 14 ...
Tip of power supply pattern, 15, 16 ... Side surface of dielectric material, 17, 18 ... Input and output terminals, 19, 20 ... First and second connection members, 25 ... Plural via holes,
26 ... A plurality of conductor rods, 27, 28 ... Dielectric top and bottom surfaces, 29, 30 ... First and second groups,

Claims (2)

[Claims] 1. A stripline filter having a filter pattern formed of at least two band-shaped conductors in a dielectric substrate having ground patterns on the upper and lower surfaces thereof, and an electric shield means between the at least two band-shaped conductors. A stripline filter comprising: 2. The shield means comprises a via hole formed in the dielectric between the strip conductors, and a conductor member inserted into the via hole and connected to at least one of the upper surface and lower surface ground patterns. The stripline filter according to claim 1, wherein: