JP2000252704A - Dielectric filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the filter which facilitates the adjustment of coupling or the like and is easy to design by connecting resonators, i.e., microstrip lines by transmission lines. SOLUTION: The dielectric filter is equipped with the transmission lines, which each have one end grounded and the other end made open, on a dielectric substrate; and input/output-side transmission lines are connected to input/output electrode patterns and at least two transmission lines are connected by a conductor pattern. For example, this dielectric filter has more than one parallel strip lines 11 and 12 formed on the top surface of an electrically conductive substrate 10 and connected to input/output conductor patterns 13 and 14. The conductor strip lines 11 and 12 each have one end as a short terminal which extends to the end surface of the substrate 10 and is connected as an earth conductor and the other end as an open end which does not reach the end surface of the substrate 10. Then the conductor strip lines 11 and 12 are connected by a conductor pattern 15 and thus coupled together.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter for obtaining a filter characteristic by coupling a conductor microstrip line resonator on a dielectric substrate, and to a coupling structure thereof.

[0002]

2. Description of the Related Art Conventionally, in a stripline type filter, various resonators are coupled by forming grooves between striplines serving as resonators, or by combining different types of dielectrics. Make up the filter.

[0003]

However, in such a coupling method, it is difficult to predict the actual permittivity between the resonators, and it is difficult to adjust the resonance frequency and the coupling. An object of the present invention is to provide a dielectric filter that can be easily adjusted for coupling and the like and is easily designed.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems by connecting a plurality of resonators, that is, microstrip lines, with a transmission line.

That is, in a dielectric filter having a plurality of transmission lines having one end grounded and the other end opened on a dielectric substrate, the input / output side transmission lines are connected to the input / output electrode patterns, respectively. It is characterized in that two transmission lines are connected by a conductor pattern.

Specifically, in a dielectric filter having a plurality of strip lines on a dielectric substrate, one end of which is grounded and the other end of which is open, a plurality of parallel strip lines are connected at one end to the end surface of the dielectric substrate. It extends and is grounded, the other end is opened without extending to the end face of the dielectric substrate, the conductor pattern connected to the strip line at both ends extends to the end face of the dielectric substrate and is connected to the terminal electrode, and the conductor between the strip lines is connected. It is characterized by being connected by a pattern.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A dielectric filter according to the present invention comprises:
As shown in FIG. 1, two or more conductor strip lines 11 and 12 parallel to the surface of a dielectric substrate 10 are formed and connected to input / output conductor patterns 13 and 14. One end of the conductor strip line is a short end reaching the end surface of the substrate and connected to the ground conductor, and the other end is an open end not reaching the end surface of the substrate. Conductor strip lines 11 and 12 are conductor patterns 15
And a connection is obtained.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A description will be given of a comb-line filter shown in FIG. 1 as an example. The conductor pattern shown in FIG. 1 was formed on the surface of a dielectric substrate having a dielectric constant of 37 and a thickness of 1 mm, and a ground electrode was formed on the back surface. FIG. 2 shows a planar structure of the conductor pattern. Set the total length of strip lines 21 and 22 to 8
mm and the line width was 0.4 mm. I / O conductor pattern 23, 2
4 was 2 mm, and the length of the conductor pattern 25 connecting the conductor strip lines 21 and 22 was 2 mm.

The distance between the short end and the center of the connecting position of the conductor pattern 25 is x, and the distance from the short end to the connecting position of the input / output rigid patterns 23 and 24 is y. , Its insertion loss, center frequency, and 3 dB bandwidth characteristics. Table 1 shows the results.

[0010]

[Table 1]

As the connection position moves away from the short-circuit end, the insertion loss decreases and the center frequency increases. A particularly remarkable change is the 3 dB bandwidth, and the bandwidth can be made very wide depending on the formation position of the connecting conductor pattern. this is. This shows that the coupling between strip lines serving as resonators is very strong.

In FIG. 2, x is fixed at 1.0, y is fixed at 2.0, and the line width is fixed.
Several types of samples, 0.4 mm and wider, were made and their properties were compared. Table 2 shows the results.

[0013]

[Table 2]

From the above results, when the line width of the conductor is widened, the coupling is strengthened, and the bandwidth can be widened. Other characteristics were almost unchanged. In Tables 1 and 2, there is a difference in characteristics at the same size, which is considered to be due to variations in the dielectric constant of the dielectric substrate.

The present invention is not limited to the two-element comb-line type filter as described above, but can be applied to three or more elements, or to only a part of them. And it can be used not only as a bandpass filter but also as a band elimination filter or the like. The shape of the transmission line is not limited to a straight strip line.

[0016]

According to the present invention, strong coupling between the resonators can be obtained only by connecting the conductor strip lines, and a dielectric filter having a wide bandwidth can be obtained. Further, by adjusting the formation position and width of the conductor pattern, the coupling state can be arbitrarily set.

Further, since the coupling state can be set only by designing the conductor pattern, a dielectric filter which is easy to design and has stable characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a plan view showing an embodiment of the present invention.

[Explanation of symbols]

 10: Dielectric substrate 11, 12, 21, 22: Conductor strip line 13, 14, 23, 24: Input / output conductor pattern 15, 25: Connection conductor pattern

Claims (3)

[Claims] 1. A dielectric filter comprising a plurality of transmission lines having one end grounded and the other end open on a dielectric substrate, wherein input / output side transmission lines are connected to input / output electrode patterns, respectively. A dielectric filter, wherein two transmission lines are connected by a conductor pattern. 2. A dielectric filter comprising a plurality of strip lines, one end of which is grounded and the other end of which is open on a dielectric substrate, wherein the plurality of strip lines are arranged in parallel, and input and output to and from the strip lines at both ends. 1. A dielectric filter to which an electrode pattern is connected and a strip line is connected by a conductor pattern. 3. A dielectric filter comprising a plurality of strip lines, one end of which is grounded on a dielectric substrate and the other end of which is open, wherein a plurality of parallel strip lines extend at one end to an end surface of the dielectric substrate and are grounded. The other end is opened without extending to the end face of the dielectric substrate, the conductor pattern connected to the strip line at both ends extends to the end face of the dielectric substrate and connected to the terminal electrode, and the strip lines are connected by the conductor pattern. A dielectric filter characterized by being performed.