JPH05114801A - Method for adjusting frequency in microwave strip line filter - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] To enable response frequency characteristics to be adjusted accurately and easily within a large adjustment range regardless of the shape of the filter. [Structure] A pair of dielectric substrates 1 and 2 are connected to a plurality of resonance electrodes 3,
In the microwave stripline filter formed by sandwiching and fixing four and five, the resonance electrodes 3, 4, 5
The open end of is exposed or connected to the ground conductor 6 by the strips 8, 9 and 10, and the strips 8, 9 and 10 are cut to adjust the frequency response.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frequency adjusting method for a microwave stripline filter which can be used as a bandpass filter, for example.

[0002]

2. Description of the Related Art Conventionally, various types of microwave stripline filters used as bandpass filters in the microwave region have been proposed. One example thereof is a BaO-TiO ₂ system as shown in FIG. , BaO
- TiO ₂ - high dielectric constant rare earth such as, two sheets of dielectric substrate 1a made of a dielectric ceramic low loss, made from those stacked 1b, the dielectric substrate 1a, an outer surface and an outer surface of the 1b Are formed with ground conductors 2a and 2b, respectively, and a plurality of band-shaped resonance conductors 3a acting as a filter are formed on the inner surface of one dielectric substrate 1a. One end of each band-shaped resonance conductor 3a is connected to the ground conductor 2a. They are connected to form a short-circuited end and the other end is configured as an open end so as not to be connected to a ground conductor, and the band-shaped resonant conductor 3a is formed in an interdigital type by arranging the open ends alternately ( Kaisho
54-87460).

By the way, it is known that the response frequency of this type of stripline filter depends on the dielectric constant of the dielectric substrate used and the size of each resonance conductor. Therefore, when manufacturing a filter, the dielectric constant of the dielectric substrate used and the dimensions of the resonant conductor are strictly controlled, but variations in manufacturing cannot be avoided and frequency adjustment is required after stacking both dielectric substrates. I need to do it. In the structure shown in FIG. 8, the frequency of the filter is designed to be lower than a desired value, two dielectric substrates 1a and 1b are superposed and laminated, and then, as shown by reference numeral A in the drawing, Dielectric substrate
Each band-shaped resonance conductor of the ground conductor 2b formed on the upper surface of 1b
The floating capacitance between the resonance conductor 3a and the ground conductor 2b is reduced by partially cutting a portion that vertically opposes the open end of 3a,
A method of increasing the frequency to adjust to a desired response frequency is adopted. However, in this method, even if the response frequency is adjusted to the desired response frequency, the shaving portion A comes into contact with or comes close to the inner wall of the case when the filter body is subsequently housed in the case, so that the distributed capacity adjusted by the fluctuation of the floating capacity is adjusted. Has a drawback that the response frequency shifts.

In order to solve such a drawback, for example, in Japanese Unexamined Patent Publication No. 1-251801, a plurality of strip-shaped resonance conductors are sandwiched between the laminated surfaces of two dielectric substrates to be laminated. It has been proposed to form an opening for adjusting the response frequency on the peripheral side surface of the dielectric substrate at a position corresponding to the short-circuited end of the conductor. Further, in Japanese Patent Application Laid-Open No. 2-292901, a pair of dielectric substrates each having an earth conductor formed on the outer surface are laminated and fixed by sandwiching a plurality of resonance electrodes formed on at least one inner surface of these dielectric substrates. , A microwave stripline filter in which one end of each resonance electrode is connected to the ground conductor on the outer surface to make a short-circuit end, and the other end of each resonance electrode is separated from the ground conductor on the outer surface and terminated to make an open end, Partially cutting off the ground conductor on the peripheral side surface of the dielectric substrate facing the open end of the resonance conductor,
Part of the ground conductor that is in contact with the short-circuited end of the resonance conductor is partially removed, and the open end of the resonance conductor is made to face the notch groove formed on the peripheral side surface of the facing dielectric substrate. It has been proposed to remove the ground conductor.
Further, in Japanese Patent Application No. 1-219580, a plurality of strip-shaped resonant conductors are sandwiched between two dielectric substrates, and a ground conductor is formed on the outer surface other than the peripheral side surface of each dielectric substrate. Then, extend the short-circuited end of each band-shaped resonant conductor to the ground conductor along the peripheral side surface, and extend the open end to the edge of the peripheral side surface of the dielectric substrate. It has been proposed to scrape off with the peripheral side surface of the body substrate and to add a correction conductor to the open end face of each band-shaped resonant conductor.

[0005]

However, the frequency adjustment method proposed hitherto has the following problems. That is, it is easy to lower the response frequency of the filter in the method proposed in Japanese Patent Laid-Open No. 1-251801, but if the response frequency becomes too low due to the formation of the response frequency adjusting aperture, it is raised. Cannot be adjusted, making adjustments difficult. Further, the method proposed in Japanese Patent Laid-Open No. 2-292901 can increase the response frequency of the filter, but the amount of adjustment is small, and when the distance between the open end of the resonant conductor and the ground conductor increases, The adjustment effect decreases. Further, in the method according to Japanese Patent Application No. 1-219580, although the response frequency of the filter can be increased and the adjustment amount thereof is large, the outer shape of the stripline filter is specified as a special shape, and the productivity is improved. Be damaged.

Therefore, the present invention solves the problems associated with such a conventional filter frequency adjustment method, and the response frequency characteristic can be adjusted accurately and within a large adjustment range regardless of the shape of the filter. It is an object of the present invention to provide a frequency adjustment method for a microwave stripline filter.

[0007]

In order to achieve this object, according to the first aspect of the present invention, a pair of dielectric substrates each having an earth conductor formed on the outer surface thereof are provided. A plurality of resonance electrodes formed on at least one inner surface are sandwiched and fixed in layers, one end of each resonance electrode is connected to a ground conductor on the outer surface to make a short-circuit end, and the other end of each resonance electrode is a ground conductor on the outer surface. The frequency adjustment method of the microwave stripline filter that is separated from and terminated at the open end is to connect or close the open end of each resonance electrode to the ground conductor on the outer surface with a strip line and cut each strip line. Therefore, the frequency response is adjusted. The frequency adjusting method according to the second aspect of the present invention is
The open end of each resonance electrode is connected to or close to the ground conductor on the outer surface with a strip line, and the frequency is obtained by cutting the connection part or proximity part of each strip line with the ground conductor together with the ground conductor part close to it. It is characterized by adjusting responsiveness.

[0008]

In the method of adjusting the frequency of the microwave stripline filter according to the present invention, the exposed strips for connecting the open ends of the resonance electrodes to the ground conductor on the outer surface or in the vicinity thereof are very thin as compared with the resonance electrodes, and the response The frequency is almost determined by the length of each resonance electrode. Therefore, each exposed strip does not substantially impair the response frequency characteristic of each resonant electrode. Also,
The cutting of each exposed fine line is performed by directly cutting off using an appropriate cutting means such as a drill or a laser trimmer, whereby the response frequency can be increased. Further, since the frequency is adjusted by cutting the exposed fine line, the frequency correction portion can be freely selected, and the shape of the filter can be designed arbitrarily.

[0009]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 7 of the accompanying drawings. FIG. 1 shows an embodiment of the present invention, in which the illustrated stripline filter is BaO--TiO.
₂ or BaO-TiO ₂ -rare earth-based dielectric ceramics having a high dielectric constant and a low loss, such as two dielectric substrates 1 and 2, and a plurality of dielectric substrates (2 in the structure shown in FIG. ), The band-shaped resonance conductors 3, 4, and 5 are formed, and the other dielectric substrate 2 is superposed on the band-shaped resonance conductors 3, 4, and 5 and fixed by pressure bonding. 2, the ground conductor 6, on the outer surface and the peripheral side surface, respectively.
7 is formed by plating or vapor deposition. Further, one end of each band-shaped resonance conductor 3, 4, 5 is connected to the ground conductor 6 to form a short-circuit end, and the other end of each band-shaped resonance conductor 3, 4, 5 is separated from the ground conductor 6 and terminated. Has an open end. The open ends of the band-shaped resonance conductors 3, 4, and 5 are alternately arranged in opposite directions to form an interdigital type.
The open ends of the strip-shaped resonance conductors 3, 4, 5 are connected to the ground conductor 6 by the fine lines 8, 9, 10 for frequency adjustment. These strip lines 8, 9 and 10 are used for the strip-shaped resonance conductors 3, 4, 5 respectively.
The band-shaped resonant conductors 3, 4, and 5 are formed to be very thin so as not to substantially affect the response frequency characteristic of the. Further, with respect to the other dielectric substrate 2 superposed on the band-shaped resonant conductors 3, 4, 5 formed on the upper surface of the one dielectric substrate 1, the dimension in the direction crossing the band-shaped resonant conductors 3, 4, 5 is one. Of the dielectric substrate 1, but the dimension in the direction along the band-shaped resonant conductors 3, 4, 5 is approximately the length between the open ends of the band-shaped resonant conductors 3, 5 and the band-shaped resonant conductor 4. , So that when the other dielectric substrate 2 is overlapped with a virtual line in FIG. 1 and as shown in a partially enlarged view in FIG. 2, the fine lines 8, 9, 10 for frequency adjustment are exposed. It remains as it is, making it extremely easy to carry out shaving when adjusting the frequency. The strip-shaped resonance conductors 3, 4, 5 and the frequency adjusting thin lines 8, 9, 10 on one dielectric substrate 1 are formed by plating, vapor deposition, or the like in the same manner as the formation of the ground conductors 6, 7. It can be performed using an appropriate film forming method.

In the stripline filter thus constructed, the response frequency is taken into consideration in consideration of manufacturing variations such as the dielectric constants of the dielectric substrates 1 and 2 and the lengths of the band-shaped resonant conductors 3, 4 and 5. Is designed to be slightly lower than the desired level, so that the frequency characteristics of the filter are adjusted after stacking and fixing. As shown in FIG. 3, for example, the striped wire 9 extending from the open end of the band-shaped resonant conductor 4 together with the ground conductor 6 formed on the peripheral side surface of the dielectric substrate 1 is provided with a suitable material such as a drill or a laser trimmer from the outside of the side surface. Using the means, it is directly excised as indicated at 11. This allows the response frequency to be adjusted higher. In this case, since each fine line for frequency adjustment is exposed, there is an advantage that the cutting operation can be easily performed.
By sequentially performing such adjustment operation for each band-shaped resonant conductor, it becomes possible to easily and accurately adjust the response frequency of the filter to a desired value.

Further, as shown in FIGS. 4 and 5, the portion 6a of the ground conductor 6 on the peripheral side surface of the dielectric substrate 1 connected to each strip line (only the strip line 9 is shown in the drawings). Can be separated from the other parts of the ground conductor 6 by the separating part 12, and in that case, as shown in FIG. 5, the part 6a of the ground conductor 6 is partially connected by being connected to the fine line 9. Adjustment of the response frequency can be performed by cutting.

By the way, in the illustrated embodiment, each strip for frequency adjustment is connected to the ground conductor, but each strip as shown in FIG. 6 (only the strip 9 is shown in the drawing). Can also be configured to terminate at a position close to the ground conductor 6 formed on the peripheral side surface of the dielectric substrate 1. As shown in FIG. 7, the adjustment of the response frequency in this case can be performed by partially removing the end portion of the striped wire 9 together with the ground conductor 6 from the outside of the side surface as in the case of FIG. Further, although the strip line 9 is exposed in each of the embodiments, the side line of the upper dielectric substrate 2 may be extended to be flush with the side face of the lower substrate 1 to cover the strip line 9, In this case, it may be partially scraped off together with the substrate from the outside by a drill or the like.

Further, although the above-mentioned embodiment is applied to the structure in which the resonance conductor is formed only on one of the dielectric substrates 1, the method of the present invention is such that the resonance conductors having the mirror image pattern are formed on both the dielectric substrates. Can be similarly applied to any type in which the resonance conductor is formed or the resonance conductor is formed in any type other than the interdigital type, for example, a comb line type. Furthermore, the present invention is equally applicable to stripline filters having resonant conductors other than three.

[0014]

As described above, according to the method of the present invention, the open end of each resonance electrode is connected to or brought close to the earth conductor on the outer surface by a strip line, and each strip line is cut to obtain the Since it is configured to adjust the frequency response, it directly acts on the resonance electrode unlike the one using the floating capacitance, so that the adjustment effect is large and the adjustment range can be made large. Moreover, when the fine lines are exposed, not only can the shaving work be facilitated and the frequency adjustment work can be performed easily, but the frequency adjustment part can be freely selected, and therefore the shape of the filter can be arbitrarily selected. Will be able to.

[Brief description of drawings]

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

FIG. 2 is an enlarged plan view of a main part of the stripline filter before adjustment shown in FIG.

3 is an enlarged plan view of an essential part showing a state where the stripline filter of FIG. 1 is adjusted.

FIG. 4 is an enlarged plan view of a main part of a stripline filter before adjustment according to a modified embodiment of the present invention, corresponding to FIG.

5 is an enlarged plan view of a main part showing an adjusted state of the stripline filter of FIG. 4.

FIG. 6 is an enlarged plan view of a main part of a stripline filter before adjustment according to another modification of the present invention, corresponding to FIG. 2.

7 is an enlarged plan view of a main part showing an adjusted state of the stripline filter of FIG.

FIG. 8: A partially cutaway perspective view showing an example of a conventional stripline filter.

[Explanation of symbols]

 1: Dielectric Substrate 2: Dielectric Substrate 3: Strip Resonant Conductor 4: Strip Resonant Conductor 5: Strip Resonant Conductor 6: Earth Conductor 7: Earth Conductor 8: Fine Line for Frequency Adjustment 9: Fine Line for Frequency Adjustment Line 10: Fine line for frequency adjustment 11: Cutting section

Claims (2)

[Claims] 1. A pair of dielectric substrates each having a ground conductor formed on the outer surface thereof, and a plurality of resonant electrodes formed on the inner surface of at least one of the dielectric substrates are sandwiched and fixed together, and one end of each resonant electrode is formed. Is connected to the earth conductor on the outer surface to make a short-circuited end, and the other end of each resonance electrode is separated from the earth conductor on the outer surface and terminated to make an open end. A frequency adjustment method for a microwave stripline filter, characterized in that the open end of the electrode is connected to or close to the earth conductor on the outer surface by a fine line, and the frequency response is adjusted by cutting each fine line. .. 2. A pair of dielectric substrates each having an earth conductor formed on the outer surface thereof are laminated and fixed by sandwiching a plurality of resonance electrodes formed on the inner surface of at least one of these dielectric substrates, and one end of each resonance electrode. Is connected to the earth conductor on the outer surface to make a short-circuited end, and the other end of each resonance electrode is separated from the earth conductor on the outer surface and terminated to make an open end. The open end of the electrode is connected to or close to the ground conductor on the outer surface with a strip wire, and the frequency response is obtained by cutting the connection part or the proximity part of each strip wire with the ground conductor together with the ground conductor part close to it. A method for adjusting the frequency of a microwave stripline filter, which is characterized in that: