JPH0824242B2 - Strip line type filter - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strip line type filter having a plurality of resonator conductors arranged between dielectric substrates. More specifically, the present invention relates to a strip line type filter in which a dielectric substrate has a multilayer structure of three or more layers, and adjacent resonator conductors are arranged between different layers to reduce the dimension in the filter longitudinal direction.

[0002]

2. Description of the Related Art As shown in FIG. 11, a stripline filter includes a plurality of (here, three) resonator conductors 10 arranged in parallel, and L-type input / output conductors 12 located at both ends thereof.
It has two dielectric substrates 14 sandwiching them. The resonator conductor 10 and the L-type input / output conductor 12 are integrally manufactured to have a substantially comb shape by etching a metal plate or the like. That is, the resonator conductors 10 are open-ended, the base ends are commonly connected, and the L-type input / output conductors 12 are also commonly connected on the same side. An outer conductor made of a conductive material is provided on the outer surface of the dielectric substrate 14 except for one surface thereof, and the resonator conductor 10 and the L-type input / output are arranged so that the surfaces where the dielectric is exposed face each other inward. The conductor 12 is sandwiched. Further, the upper and lower outer conductors are connected by metal fittings (not shown) provided on the outside and grounded.

As a result, a filter represented by an equivalent circuit in which the resonators 16 are coupled by the inductance L is obtained as shown in FIG. The spacing between the resonator conductors and the spacing between the resonator conductors at both ends and the L-type input / output conductor are determined by the desired bandwidth, the resonator conductor width / thickness, the thickness of the dielectric substrate, and the like.

[0004]

In the above-described stripline filter having the conventional structure, it is difficult to reduce the longitudinal dimension of the filter because the spacing between the resonator conductors is determined by the required bandwidth. In order to reduce the size, there is no method in the prior art other than increasing the dielectric constant of the dielectric substrate used, but various compositions and manufacturing methods have attempted to increase the dielectric constant of the dielectric ceramic composition for microwaves. However, there are certain limits.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a stripline filter having a structure in which the dimension in the longitudinal direction of the filter can be reduced without reducing Q ₀ as much as possible. Another object of the present invention is to provide a stripline type filter that can easily realize a polarized configuration.

[0006]

According to the present invention, a plurality of resonator conductors arranged in parallel are sandwiched by a dielectric substrate, an outer conductor is provided outside the resonator substrate, and the base end of each resonator conductor is short-circuited to the outer conductor. This is a stripline filter with open ends and input / output conductors on both sides. A feature of the present invention is that, in this structure, three or more dielectric substrates are provided, adjacent resonator conductors are arranged between different layers, and both ends are open strips.
Another intermediate conductor is placed in the same layer as the resonator conductor in parallel with the resonator conductor, and the resonator conductors are polar-coupled through another intermediate conductor whose both ends are open.

Input / output conductors are positioned near the resonator conductors at both ends for input / output coupling. The input / output conductors are provided on the same layer between the input side and the output side. Then, the overall structure of the filter is a symmetrical conductor arrangement structure in the input half and the output half.

[0008]

[Operation] When adjacent resonator conductors are arranged in different layers,
The thickness of the dielectric substrate located between them substantially widens the spacing between adjacent resonator conductors. Therefore, in order to maintain the same degree of coupling, it is necessary to reduce the distance between the resonator conductors in the horizontal direction. That is, by increasing the thickness of the dielectric substrate between them, the interval becomes narrower, and the dimension in the longitudinal direction of the entire filter becomes shorter. However, if it is made too narrow, there is a possibility that resonator conductors on the same layer will approach each other and be coupled, so there is a certain limit. On the contrary, the filter can be polarized by adjusting the coupling amount.

When another conductor whose both ends are open is inserted between the layers, an electric field is gathered therein and a part of the signal can be distributed.
It has a polar structure and its adjustment is easy.

[0010]

FIG. 1 is a perspective view of an embodiment of the present invention, FIG. 2 is an exploded perspective view thereof, and FIG. 3 is a sectional view showing an example using three resonator conductors. Two resonator conductors 20a, 20c
And L-type input / output conductors 22a and 22b located at both ends thereof
Are integrally manufactured to have a substantially comb shape by etching a metal plate or the like. Both of the resonator conductors 20a and 20b are open-ended type, the base ends of which are continuous with the common conductor 26, and L
The mold input / output conductors 22a and 22b are also continuous with the common conductor 26 on the same side. Separately, the resonator conductor 20b is manufactured by etching a metal plate or the like. These are 0.1mm
About the thickness is enough. These conductors are sandwiched between the upper, middle and lower three layers of dielectric substrates 24a, 24b and 24c.

External conductors are provided on the upper surface and four side surfaces of the upper dielectric substrate 24a. An outer conductor is provided on the side surface of the middle-layer dielectric substrate 24b except the vicinity of the lead-out portion of the input / output conductor. External conductors are provided on the entire side surface and lower surface of the lower dielectric substrate 24c except for the vicinity of the lead-out portions of the input / output conductors. These outer conductors are formed by metallizing a conductive material such as silver. Therefore, the lower surface of the upper dielectric substrate 24a, the upper and lower surfaces of the middle dielectric substrate 24b, and the lower dielectric substrate 24c.
The upper surface of the dielectric is exposed. A metal plate having two resonator conductors 20a and 20c is sandwiched between a lower-layer dielectric substrate 24c and an intermediate-layer dielectric substrate 24b.
0b is a middle-layer dielectric substrate 24b and an upper-layer dielectric substrate 24
Clap with a. At this time, the edge of the common conductor 26 is projected slightly outward, and the resonator conductor 20b is positioned exactly in the middle of the two resonator conductors 20a and 20c and its one end (on the same side as the common conductor 26). Are arranged so as to slightly project from the dielectric substrate. Then, the end portions of the common conductor 26 and the resonator conductor 20b are connected to the outer conductor by soldering or the like at their protruding portions. Therefore, the input / output conductors 22a and 22c
Are located between the same layers, and the input side half and the output side half have symmetrical conductor arrangements when viewed in the whole filter.

.., 24c change the force of holding the conductor, the filter characteristics change. Therefore, it is important to firmly fix it with a certain force. Therefore, although not shown, a metal case composed of a bottom plate provided with a protrusion for grounding and a lid is used, and a laminated dielectric substrate sandwiching the resonator conductor and the like is placed and a certain pressure is applied to the lid. Fix in the state. For example, a window is provided on the bottom plate and the lid, and the window is used to solder and connect to the outer conductors of the upper and lower dielectric substrates, and at the same time ground.
In order to obtain stable characteristics, place 3 near the input / output conductor.
It is desirable to ground the outer conductor of the layer's dielectric substrate.

As a result, an equivalent circuit similar to that shown in FIG. 12 can be obtained. The strength of the coupling can be controlled by the width and thickness of the resonator conductor and the thickness of the middle dielectric substrate. The frequency can be adjusted by removing the outer conductor portion of the dielectric substrate facing the open end of the resonator conductor. Therefore, each resonator conductor has a structure in which the open end of the resonator conductor extends close to the side surface of the dielectric substrate. In this way, the dielectric substrate can be standardized and standardized, and the desired filter can be obtained only by designing the conductor.

FIG. 4 is a perspective view of a resonator conductor and an input / output conductor used in another embodiment of the present invention, and FIG. 5 is a perspective view of a filter using the same. Since the basic structure is the same as that of the above-mentioned embodiment except for the conductor portion, the corresponding members are designated by the same reference numerals and the description thereof is omitted. In this embodiment, the three resonator conductors 30a, 30b, 30c and the L-type input / output conductors 32a, 32b are continuously integrated by a common conductor 36. The intermediate resonator conductor 30b is formed so as to have a step difference with respect to the other resonator conductors 30a and 30c, and the step is exactly the middle-layer dielectric substrate 24b.
Set to a size that can insert. This conductor is also manufactured by etching a metal plate.

6 and 7 show another embodiment of the present invention. Each is an example in which five resonator conductors 40 are arranged. In FIG. 6, three dielectric substrates 44 are used.
Second and fourth resonator conductors are arranged between the first and third dielectric substrates, and the first, third, and third resonator conductors are arranged between the second and third dielectric substrates.
A fifth resonator conductor is arranged. In FIG. 7, four dielectric substrates 44 are used, a third resonator conductor is arranged between the dielectric substrates of the first and second layers from above, and the dielectric substrate of the second and third layers is arranged between them. The second and fourth resonator conductors are arranged in the above, and the first and fifth resonator conductors are arranged between the dielectric substrates of the third layer and the fourth layer. The plurality of dielectric substrates may have different thicknesses and different permittivities depending on desired characteristics. As a result, a 5-stage filter having an equivalent circuit as shown in FIG. 8 is obtained.

FIG. 9 shows still another embodiment of the present invention. The basics of the filter are the same as those shown in FIG. The difference from this is that, in this embodiment, another conductor whose both ends are open is interposed between the dielectric substrates, and the resonator conductors are polar-coupled via the other conductor. First and third intermediate conductors (metal plates) 50a, 50 having the same thickness as both ends (outside the second and fourth resonator conductors) of the second and third dielectric substrates are provided.
c is provided. In addition, a second intermediate conductor (metal plate) 50b is provided at the center of the third and fourth dielectric substrates. The conductors 50a, ..., 50c are not connected to anything, and are caught electrically in a floating state. By doing so, a capacitance C _a is formed between the input / output conductor and the first intermediate conductor, and similarly, the capacitance C _a is formed between the first intermediate conductor and the second resonator conductor.
_b is the capacitance C _c between the second resonator conductor and the second intermediate conductor, and the capacitance C _d is the fourth resonator conductor between the second intermediate conductor and the fourth resonator conductor. A capacitance C _e is formed between the conductor and the third intermediate conductor, and a capacitance C _f is formed between the third intermediate conductor and the input / output conductor. By inserting the intermediate conductor in this way, an electric field is collected, and this can be used to distribute a part of the signal. By appropriately selecting the size, shape, and position of the intermediate conductor, the equivalent circuit becomes as shown in FIG. 10, and the polarized filter can be easily constructed.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to such a configuration. The number of dielectric substrates and the number of resonator conductors can be changed appropriately. The resonator conductor, the input / output conductor, the intermediate conductor, etc. may be formed of a conductor pattern instead of a metal plate.

[0018]

As described above, according to the present invention, since the dielectric substrate has three or more layers and the adjacent resonator conductors are arranged between different layers, the distance between the resonator conductors can be shortened in plan view.
Even if the number of stages increases, the size in the longitudinal direction does not increase and the filter can be downsized. Further, a polar filter can be easily obtained by appropriately disposing an intermediate conductor whose both ends are open.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of a stripline filter according to the present invention.

FIG. 2 is an exploded perspective view of the filter shown in FIG.

FIG. 3 is a sectional view of FIG.

FIG. 4 is a perspective view of a conductor used in another embodiment of the present invention.

5 is a perspective view of a stripline filter using the conductor of FIG.

FIG. 6 is a sectional view of another embodiment of the present invention.

FIG. 7 is a sectional view of another embodiment of the present invention.

FIG. 8 is an equivalent circuit diagram of the filters of FIGS. 6 and 7.

FIG. 9 is a sectional view of still another embodiment of the present invention.

10 is an equivalent circuit diagram of the filter shown in FIG.

FIG. 11 is a perspective view of a stripline filter according to the related art.

12 is an equivalent circuit diagram of the filter shown in FIG.

[Explanation of symbols]

 20a, 20b, 20c Resonator conductor 22a, 22b L type input / output conductor 24a, 24b, 24c Dielectric substrate

 ─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP 62-254501 (JP, A) JP 53-72549 (JP, A) JP 63-128801 (JP, A) JP 62- 51803 (JP, A) Actual development Sho 56-95102 (JP, U) US Patent 4418324 (US, A)

Claims (1)

[Claims] 1. A plurality of resonator conductors are sandwiched between dielectric substrates,
An outer conductor is provided on the outside thereof, a base end of each resonator conductor is connected to the outer conductor, an end is opened, and a strip line type filter having input and output conductors on both sides is provided with three or more dielectric substrates. Adjacent resonator conductors are placed between different layers, and another strip-shaped intermediate conductor with open ends is used for the resonator.
A strip line type filter characterized in that it is arranged in the same layer as the conductor in parallel with the resonator conductor, and is polarized-coupled between the resonator conductors through another intermediate conductor whose both ends are open.