JPH0520921B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a structure for adjusting the characteristics of a stripline filter, and particularly to an improved adjustment structure that can shorten the working time for adjustment. .

[Conventional technology]

Conventionally, for stripline filters used as bandpass filters, for example, the design values and measured values of the filter characteristics may not match, and in such cases, the characteristics must be adjusted to achieve the desired design values. I'm trying to adjust it. Conventionally, as a method for adjusting this characteristic, for example,
As shown in the publication, a dielectric chip made of a small ceramic piece is arranged between the resonant electrodes to adjust the degree of coupling, or the dielectric chip is arranged at the tip of the resonant electrode. There is a method that adjusts the resonance frequency. However, in the above method using ceramic chips, the amount of change in characteristics due to one chip is small, so if the difference between the design value and the measured value is large, the number of chips must be increased, and when making fine adjustments. However, this process is not easy, and the adjustment process takes a long time, leading to an increase in costs.

Therefore, as a characteristic adjustment structure that can shorten the above-mentioned work time, an adjustment structure that uses a metal conductive chip instead of the ceramic chip has been proposed, as shown in Japanese Utility Model Publication No. 61-22325. has been done. In the case of this metal chip,
Compared to ceramic chips, it has a characteristic that the amount of change in characteristics is larger, so adjustment time can be shortened.

[Problem that the invention seeks to solve]

However, the conventional metal chip described above has a problem in that the amount of change in characteristics is too large due to the material it is made of, and improvements are needed to facilitate adjustment work. Further, when making fine adjustments, the chip must be shaved, but this is not easy to do in the case of the metal chip, and improvements in this respect are also required. In addition, when using the conventional metal chip described above, if it is placed between the resonant electrodes, it may be shot due to variations in the placement position, and if it is placed at the tip of the resonant electrode with an adhesive,
Depending on the state of the adhesive, the electrode may be equivalently elongated, or an effect similar to that of a capacitor may be produced, resulting in another problem in that frequency characteristics vary.

The present invention has been made in order to solve the above-mentioned conventional problems, and it is possible to shorten the adjustment time of the above-mentioned filter, and also to solve the problems of shortness and variation in frequency characteristics when metal chips are used. The purpose is to provide a structure for adjusting the characteristics of a prine filter.

[Means for solving problems]

The present invention provides a structure for adjusting the characteristics of a stripline filter, such as the degree of coupling K and the resonance frequency _f0 , in which a plurality of resonant electrodes are formed at predetermined intervals on the upper surface of a dielectric substrate. The present invention is characterized in that an adjustment chip formed by covering the upper surface of a dielectric chip with a conductive material is disposed between the resonant electrodes or at least one of the tips of the resonant electrodes.

Here, the adjustment chip of the present invention can be realized by employing, for example, a ceramic chip with electrodes printed on the top surface.

[Effect]

According to the characteristic adjustment structure of the stripline filter according to the present invention, the adjustment chip is placed between the resonant electrodes when adjusting the degree of coupling K, and between the resonant electrodes when adjusting the resonant frequency _f0 . The upper surface of this adjustment chip is coated with a conductive material, which improves its characteristics compared to the case of using a conventional chip made only of dielectric material. However, compared to conventional metal chips, the amount of change is smaller. As a result, it is possible to improve both the efficiency and ease of the adjustment work, and to shorten the time required for the adjustment work. In fine-tuning the characteristics, the adjustment chip is ground, but since the adjustment chip of the present invention is a dielectric coated with a thin conductor,
This thin film can be easily scraped off, making fine adjustment work easier.

In this case, since the conductive coating is located on the upper surface of the dielectric chip having a predetermined thickness, there is no possibility that the resonant electrodes will shoot each other due to variations in the arrangement positions of the adjustment chips. Further, there is no problem of the resonant electrode being extended or a capacitor being formed depending on the amount of adhesive, etc., and the problem of variations in characteristic adjustment is solved.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 and 2 are diagrams for explaining the adjustment structure of a stripline filter according to this embodiment, and this embodiment will be explained by taking an interdigital type filter as an example.

In the figure, 1 is an interdigital type filter, which has a ground electrode 3 on the entire lower surface of a dielectric substrate 2 made of ceramics, for example alumina (A ₂ O ₃ ), and a plurality of resonant electrodes 41, 4 on the upper surface.
2, 43 by screen printing or photoetching. The earth electrode 3 is
The resonant electrodes 41 to 43 are formed to extend from the lower surface of the dielectric substrate 2 to the upper surface via both opposing side surfaces thereof, and the resonant electrodes 41 to 43 are connected to the earth electrode 3a at the edge of the upper surface.
One ends of the resonant electrodes 41 and 43 are electrically connected to each other alternately, and external extraction electrodes 44 and 45 are connected to the resonant electrodes 41 and 43, respectively. A predetermined gap is provided between each of the resonant electrodes 41 to 43 and the opposing earth electrode 3a, and a predetermined gap is also provided between each of the resonant electrodes 41 to 43.

Reference numeral 5 designates the adjustment chip of this embodiment, which is constructed by printing electrodes 5a on the upper surface of a thin plate-shaped dielectric chip 5b made of ceramic, for example, the same material as the dielectric substrate 2. The adjustment chip 5 adjusts between the resonant electrodes 41 and 42 of the filter 1 according to the characteristics to be adjusted.
2 and 43 or at the tips of the resonant electrodes 41 to 43. Furthermore, the size of this adjustment chip 5,
The shape is not limited to that shown in the drawings, and may be determined as appropriate depending on the conditions of use.

Next, the effects of this embodiment will be explained.

In the above-mentioned interdigital type filter 1, the coupling degree K and the resonance frequency are
The case of adjusting f ₀ will be explained.

First, when adjusting the degree of coupling K, the adjustment chip 5 is glued between the resonance electrodes 41-43. In this case, chips 5 of different sizes are arranged, the arrangement position is changed, or the number of adjustment chips 5 is increased until the desired change is obtained. Further, in this case, fine adjustment can be made by cutting the electrode 5a of the adjustment chip 5, but this electrode 5a
It is much easier to shave than conventional dielectric chips and metal chips.

Next, when adjusting the resonance frequency f ₀ , the chip 5 is glued to the tip of the resonance electrode 4. In this case as well, increase the number of chips in the same way as the degree of coupling K above,
Adjust by cutting the electrode 5a.

FIGS. 3 and 4 are characteristic diagrams showing the relationship between attenuation and frequency for explaining the effects of this embodiment. In the figure, the solid line A shows the initial characteristics, the broken line B shows the characteristics when a dielectric chip is used, and the dashed line C shows the characteristics when the adjustment chip of this embodiment is used.

FIG. 3 shows a characteristic change in the degree of coupling K when the adjustment chip 5 is bonded between the resonant electrodes 41-43.
As is clear from the figure, even mode M ₁
There is not much difference in the resonant frequency between the conventional dielectric chip and this example chip, but the odd mode
Regarding the resonance frequency of _M2 , the adjustment chip of this embodiment has a larger change than that of the conventional chip, and from this point it can be seen that the effect of changing the coupling characteristics by the chip of this embodiment is greater.

FIG. 4 shows the change in the resonant frequency f ₀ when the adjustment chip 5 is bonded to the tips of the resonant electrodes 41 to 43. As is clear from the figure, when the adjustment chip of this example is used, the resonant frequency f ₀ changes significantly compared to the conventional chip, and this causes the frequency characteristics of the adjustment chip of this example to change significantly. It can be seen that the change effect is becoming larger.

As described above, according to the adjustment structure of this embodiment, since the adjustment chip 5 is formed by covering the upper surface of the dielectric chip 5b with the electrode 5a, it is possible to efficiently change the degree of coupling K and the resonance frequency _f0 . Since the adjustment can be performed using a small number of adjustment chips 5, the working time for adjustment can be reduced accordingly. Furthermore, in this embodiment, since the electrodes 5a are printed, fine adjustments can be made by scraping the electrodes after adhering the adjustment chips 5, thereby further shortening the working time.

In addition, since the adjustment chip 5 of this embodiment has an electrode 5a formed on a dielectric chip 5a having a predetermined thickness, when this is placed between the resonant electrodes, the adjustment chip 5 can be used to There is no risk of the electrodes shooting out. Furthermore, when disposed on a resonant electrode, this electrode does not cause variations due to extension of the resonant electrode as in the prior art, and the accuracy of characteristic adjustment can be improved.

Although this embodiment has been described using an interdigital type filter as an example, the present invention can also be applied to a combline type filter in which the resonant electrode is formed in a comb shape, and the same effect can be obtained in this case as well.

〔Effect of the invention〕

As described above, according to the characteristic adjustment structure of the stripline filter according to the present invention, the adjustment chip formed by coating the upper surface of the dielectric chip with a conductive material is provided between the resonant electrodes or at least at the tip. Since the degree of coupling, resonance frequency, etc. can be adjusted using this method, work efficiency and ease of work can be improved.Furthermore, it is easy to scrape off the conductor during fine adjustment, which saves work time. This has the effect of reducing production costs.

[Brief explanation of drawings]

Fig. 1 is a schematic perspective view showing an interdigital filter according to an embodiment of the present invention, Fig. 2 is a perspective view showing an adjustment chip of the above embodiment, and Figs. 3 and 4 show the effects of the above embodiment. It is a characteristic diagram showing the relationship between frequency and attenuation amount for explanation. In the figure, 1 is an interdigital filter (stripline filter), 2 is a dielectric substrate,
3 is a ground electrode, 4 is a resonant electrode, 5 is an adjustment chip, 5a is an electrode (conductive material), and 5b is a dielectric chip.

Claims (1)

[Claims] 1 Characteristics of a stripline filter in which a ground electrode is formed on the lower surface of a dielectric substrate, a plurality of resonant electrodes are formed at predetermined intervals on the upper surface, and the ground electrode and one end of the resonant electrode are electrically connected. In the structure for adjusting, between the resonant electrodes or at least one of the tips of the resonant electrodes,
1. A characteristic adjustment structure for a stripline filter, characterized in that an adjustment chip is provided in which the upper surface of a dielectric chip is coated with a conductive material in the form of a thin film.