JPS63219201A - Characteristic adjusting structure of strip line filter - Google Patents

Abstract

PURPOSE:To reduce the work time by arranging an adjusting chip comprising a dielectric chip while its upper face is coated by a conductive substance to at least any of tip of a resonance electrode or between resonance electrodes so as to adjust the degree of coupling and resonance frequency or the like. CONSTITUTION:In adjusting the degree of coupling K and a resonance frequency f0 in an interdigital filter 1, when the degree of coupling K is adjusted at first, the adjusting chip 5 is sticked between resonance electrodes 41-43. In this case, the chip 5 with different size is arranged till a desired change is obtained, the arrangement position is changed or the number of the adjusting chips 5 is increased. In this case, fine adjustment is applied by cutting the electrode 5a of the chip 5. In adjusting the resonance frequency f0, the chip 5 is sticked to the tip of the electrode 4. The adjustment is applied similarly in the case with that of the degree of coupling K, by increasing the chip numbher or cutting off the electrode 5a.

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 more 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 match the desired design values. I try to do that. Conventionally, as a method for adjusting this characteristic, as shown in Japanese Utility Model Publication No. 60-7528, a dielectric chip made of a small piece of ceramic is arranged between the resonant electrodes to adjust the degree of coupling. There is a method in which the dielectric chip is disposed at the tip of a resonant electrode to adjust the resonant 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 slight correction may be required. At times, the chips are ground, but this grinding work is not easy, and the problem is that it takes a long time to make adjustments, which increases costs.

Therefore, as a characteristic adjustment structure that can shorten the above working time, an adjustment structure that employs a metal conductor 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, the amount of change in characteristics is larger than that of a ceramic chip, so the adjustment time can be shortened.

[Problem that the invention seeks to solve]

However, when using the above-mentioned metal tip, if it is placed between the resonant electrodes, there is a possibility of a short circuit due to variations in the placement position, and if it is placed at the tip of the resonant electrode with an adhesive, the adhesive may Depending on the condition of the intervening rod, the electrode may extend isometrically, or an effect similar to that of a capacitor may occur, 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 the present invention is a strip line that can shorten the adjustment time of the above-mentioned filter and also eliminate the problems of short circuits and variations in frequency characteristics when metal chips are used. The purpose is to provide a filter characteristic adjustment structure.

[Means for solving problems]

The present invention provides a structure for adjusting the characteristics, such as the degree of coupling, the resonant frequency fo, etc. of a Street-Knob line filter 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 having an upper surface of a dielectric chip covered 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 coupling degree, for example, and between the resonant electrodes when adjusting the resonant frequency f0. However, since the top surface of this adjustment tip is covered with a conductive material, this conductive material may cause changes in its characteristics compared to when a conventional dielectric tip is used. Since the amount is larger, the number of chips required can be reduced accordingly,
The time required for adjustment work can be shortened.

In this case, since the conductive coating is located on the upper surface of the dielectric chip having a predetermined thickness, there is no risk of short-circuiting between the resonant electrodes due to variations in the arrangement position of the adjustment chip. 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〕

Embodiments of the present invention will be described below with reference to the drawings.

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

In the figure, ■ is an interdigital type filter, which is made of ceramics, such as alumina (A7!tOs
) on the entire lower surface of the dielectric substrate 2,
A plurality of resonant electrodes 41, 42, and 43 are screen-printed or photo-etched on the upper surface. The ground electrode 3 is formed to extend from the bottom surface of the dielectric substrate 2 through its opposite side surfaces to the top surface, and one ends of the resonance electrodes 41 to 43 are alternately connected to the ground electrode 3a at the edge of the top surface. The resonant electrode 41.
External extraction electrodes 44 and 45 are connected to 43. A predetermined gap is provided between each of the resonance electrodes 41 to 43 and the opposing earth electrode 3a, and each resonance electrode 4
A predetermined gap is also provided between 1 and 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 described above. The adjustment chip 5 then adjusts the resonant electrode 41 of the filter 1 according to the characteristics to be adjusted.
．． 42, between 42 and 43, or at the tips of the resonant electrodes 41 to 43. In addition, 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 interdigital filter 1, a case will be described in which the degree of coupling K and the resonance frequency f0 are adjusted using the structure of this embodiment.

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

Next, when adjusting the resonance frequency f0, the tip 5 is bonded to the tip of the resonance electrode 4. In this case as well, the degree of coupling is adjusted by increasing the number of chips or cutting the electrode 5a in the same way as the degree of coupling described above.

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 when the adjustment chip 5 is bonded between the resonant electrodes 41 to 43.

As is clear from the figure, even mode M.

There is not much difference in the resonant frequency between the conventional dielectric chip and the chip of this example, but the resonant frequency of the odd mode M2 changes more significantly in the adjustment chip of this example than in the conventional chip. From this point, it can be seen that the effect of changing the coupling characteristics by the chip of this example is large.

FIG. 4 shows adjustment tips 5 at the tips of the resonant electrodes 41 to 43.
It shows the change in the resonant frequency f0 when bonding. As is clear from the figure, when the adjustment chip of this example is used, the resonant frequency f0 changes significantly compared to the conventional chip, and this causes a change in frequency characteristics due to the chip of this example. It can be seen that the effect is increasing.

As described above, according to the adjustment structure of the present embodiment, since the adjustment chip 5 in which the upper surface of the dielectric chip 5b is covered with the electrode 5a is adopted, the resonant frequency f0 can be greatly changed depending on the degree of coupling. Since 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 chip 5, thereby further shortening the working time.

Further, since the adjustment chip 5 of this embodiment has an electrode 5a formed on a dielectric chip 5a having a predetermined thickness,
When this electrode is placed between resonant electrodes, there is no risk of short-circuiting of adjacent resonant electrodes due to this electrode. Furthermore, when disposed on a resonant electrode, this electrode does not cause variations due to extension of the resonant electrode as in the past, and the accuracy of characteristic adjustment can be improved. Although the explanation has been given 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 a stripline filter according to the present invention, 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 at the tip. This allows us to adjust the coupling degree, resonance frequency, etc., so the number of chips for adjustment can be reduced due to the increased change in characteristics due to one chip, and the work time can be shortened accordingly. This has the effect of reducing production costs.

[Brief explanation of the drawing]

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 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 ink digital filter (stripline filter), 2 is a dielectric substrate, 3 is a ground electrode, 4 is a resonance electrode, 5 is an adjustment chip, 5a is an electrode (conductive material), and 5b is a dielectric chip. It is. Patent applicant Murata Manufacturing Co., Ltd. Representative Patent attorney Tsutomu No. 11 Figure 2

Claims (1)

[Claims] (1) A ground electrode is formed on the lower surface of the dielectric substrate, and a plurality of resonant electrodes are formed at predetermined intervals on the upper surface,
In a structure for adjusting the characteristics of a stripline filter in which the ground electrode and one side end of the resonant electrode are electrically connected, the upper surface of the dielectric chip is connected to a conductor between the resonant electrodes or at least one of the tips thereof. A characteristic adjustment structure for a stripline filter, characterized in that an adjustment chip coated with a substance is provided.