JPH04306003A - Band pass filter - Google Patents

Abstract

PURPOSE:To attain a high Q, to reduce an insertion loss, to make the size small and to adjust its input and output impedance optionally. CONSTITUTION:Two coil electrode patterns 41, 42 formed to one major side of a board 1 made of a dielectric material both form a loop. Then the electrodes 41, 42 are arranged in a magnetically coupled state and an electrode extract pattern 7a and a ground terminal pattern 6a led out with an interval offering a prescribed impedance from the 1st electrode 41 toward the end of the board 1 and an electrode extract pattern 7b and a ground terminal pattern 6b led out with an interval offering a prescribed impedance from the 2nd electrode 42 toward the end of the board 1 are led out on different side faces.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is applicable to
The present invention relates to a dielectric laminated bandpass filter used in portable radio equipment and the like with a frequency of .

2. Description of the Related Art Conventional resonators can be roughly divided into those using strip lines and those using coil patterns. When a bandpass filter is manufactured using such resonators, the structure is such that a plurality of resonators are magnetically coupled. Here, examples using the strip line include a 1/2 wavelength resonator with both ends of the line open, as shown in FIG. 32, and a resonator with one end of the line open, as shown in FIG.
The other end has a short-circuited 1/4 wavelength resonator. On the other hand, as a method using a coil pattern, as previously proposed by the applicant (see FIG. 34), the dielectric layer 202
There is one in which a spiral coil pattern 201 and a ground pattern 203 are formed on both sides of the coil pattern.

[Problems to be Solved by the Invention] However, the above-mentioned conventional bandpass filters using resonators each have the following problems. ■Using a strip line (a) A resonator with a resonant frequency of 2 to 3 GHz is quite large. Particularly, a bandpass filter having a structure in which a plurality of resonators are coupled causes a significant increase in size. This is due to the reasons shown below. That is, the lengths L10 and L11 of the strip lines are determined as shown in Equation 1 (1/2 wavelength resonator) and Equation 2 (1/4 wavelength resonator).

[Math 1]

[Equation 2] In Equations 1 and 2 above, λ is the wavelength, and ε is the dielectric constant of the dielectric laminate sheet. At present, the dielectric constant of a dielectric laminate sheet that can be co-fired with silver or copper and has excellent temperature characteristics cannot be increased very much, and is approximately ε≈10. Therefore, in the above equations 1 and 2, ε=1
If 0, L10=15.8mm, L11=7.9m
m, which is extremely long, leading to an increase in the size of the resonator (bandpass filter) as described above. (b) In a bandpass filter, it is desirable to adjust the input/output impedance depending on the device to be incorporated (matching the impedance between the bandpass filter and the device). However, in the case of a stripline type, since the input/output impedance has a unique value for each stripline, adjustment cannot be performed even if the extraction position is changed, and matching is not possible. ■Those using a coil pattern Since the coil pattern is spiral, magnetic flux influences each other between adjacent patterns, making it difficult for current to flow. Therefore, the effective resistance increases and the Q becomes low. for example,
In FIG. 34, pattern piece 201a and pattern piece 20
1b, the direction of current flow is the same (both D
Since the magnetic fields cancel each other out and the magnetic flux becomes coarse, it becomes difficult for current to flow and the actual resistance increases. When the Q becomes low in this way, there is a problem in that the insertion loss of the bandpass filter becomes large. The present invention was made in view of the current situation, and an object of the present invention is to provide a bandpass filter that has a high Q and low insertion loss, can be miniaturized, and can arbitrarily adjust input and output impedance. shall be.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides that two first electrodes are disposed on one main surface of a plate made of a dielectric material, while the other is arranged on the other main surface. is a bandpass filter in which second electrodes are arranged, the first electrodes both forming a loop shape, each first electrode being arranged in a magnetically coupled state, and one of the first electrodes forming a loop shape; an extraction terminal and a ground terminal that are pulled out from the electrode toward the end of the plate at intervals having a predetermined impedance;
A take-out terminal and a ground terminal are drawn out from the other first electrode toward the end of the plate body at intervals having a predetermined impedance, and the ground terminal is drawn out to different sides, and the second
The electrode has a planar shape, and the earth terminal is drawn out toward the end of the plate. Two first electrodes are disposed between one main surface of two plates made of dielectric material, while a first electrode is arranged on at least one of the other main surfaces of the two plates. A bandpass filter in which two electrodes are respectively arranged, the first electrodes both forming a loop shape, each first electrode being arranged in a magnetically coupled state, and one of the first electrodes forming a loop. An extraction terminal and a ground terminal are drawn out from the other first electrode toward the end of the plate at intervals having a predetermined impedance, and the other first electrode is drawn out toward the end of the plate at intervals having a predetermined impedance. A take-out terminal and a ground terminal are drawn out to different sides, and the second electrode has a planar shape, and the ground terminal is drawn out toward the end of the plate. Two first electrodes are arranged between one main surface of two plates made of dielectric material,
The band pass filter has second electrodes arranged on the other main surfaces of the two plates, the first electrodes both forming a loop shape, and each first electrode being magnetically coupled. a take-out terminal and a ground terminal, which are arranged in a state of
A take-out terminal and a ground terminal are drawn out from the electrode toward the end of the plate body at intervals having a predetermined impedance, and further, at least one of the second electrodes is drawn out from the second electrode at intervals having a predetermined impedance. It is characterized in that it is divided into two parts so as to have a shape slightly larger than one electrode, and a ground terminal is drawn out from each of the divided electrodes toward the end of the plate body. A third electrode having the same shape as the first electrode is formed between the first electrode and at least one of the second electrodes.

[Operation] With the above configuration, the reason is that the first electrode and the second electrode are in a so-called strip line structure facing each other, and the pattern pieces of the first electrode are adjacent to each other like a spiral coil pattern. Because of this, Q is dramatically improved, insertion loss is reduced, and skirt characteristics become sharper. Furthermore, since the first electrode has a loop shape, the dimensions of the element are reduced. In addition, the first
Since the impedance can be adjusted simply by changing the distance between the electrode extraction terminal and the ground terminal, impedance adjustment is extremely easy.

[Example] (First Example) The first example of the present invention is shown in FIG.
This will be explained below based on ~FIG. 11. 1 and 2 are diagrams showing the structure of a bandpass filter according to a first embodiment of the present invention, in which FIG. 1 is a plan view, FIG. 2 is an exploded perspective view, and FIG.
is a plan view of a dielectric sheet used in the present invention, FIG. 4 is a plan view showing a state in which a coil electrode pattern is formed on the dielectric sheet of FIG. 3, and FIG. 5 is a plan view showing a state in which a ground electrode pattern is formed on the dielectric sheet of FIG. A plan view showing the state, FIGS. 6 and 7 are views when dielectric sheets are laminated, and FIG. 6 is a front view,
FIG. 7 is a side view, FIG. 8 is a front view when the laminate is crimped,
FIG. 9 is a front view when external electrodes are formed, FIG. 10 is an equivalent circuit diagram of the band-pass filter, and FIG. 11 is a graph showing the frequency characteristics of the band-pass filter. As shown in FIG. 2, the bandpass filter of the present invention includes a dielectric layer 1 made of a plurality of dielectric sheets 101, and protective layers 2 and 3 provided above and below this dielectric layer 1. are doing. Two coil electrode patterns 41 and 42 are formed on one main surface 101a of the dielectric sheet 101 located at the top of the dielectric sheets 101. and,
These are fired and integrated together. The specific structure of the coil electrode pattern 41 is such that pattern pieces 41a and 41b are arranged in a straight line and are arranged opposite to each other.
1a and 41b through a linear pattern piece 41c provided at one end, and at the other end of the pattern piece 41b, extending in the direction of the pattern piece 41a so as to be parallel to the pattern piece 41c. It has a structure (that is, a loop shape) in which pattern pieces 41d are formed. Here, the total length L3 of the coil electrode pattern 41 is configured to be a length shown in Equation 3 below.

[Formula 3] λ is the wavelength and ε is the dielectric constant. Note that the distance L1 (see FIG. 1) between the pattern piece 41d and the pattern piece 41a is preferably equal to or less than the width L2 of the pattern piece 41a (the same applies to the pattern pieces 41b to 41d). In addition, in the following embodiments, the pattern piece 41a
- The gap between 41d is called the gap part 30. A ground terminal pattern 6a and a lead-out electrode pattern 7a are connected to both coil electrode patterns 41, and the ends of the ground terminal pattern 6a and lead-out electrode pattern 7a extend to the side surface A of the bandpass filter. There is. On the other hand, the coil electrode pattern 42 has substantially the same shape as the coil electrode pattern 41 having the above structure, as shown in FIG. However, the gap 31 is formed between 42b and 42c, and the ends of the ground terminal pattern 6b and the extraction electrode pattern 7b are on the side surface B of the bandpass filter.
It is different in that it extends to the opposite side (the opposite side to the side A). The pattern pieces 41d and 42c of both the coil electrode patterns 41 and 42 are arranged adjacent to each other and are magnetically coupled to each other. A ground electrode pattern 5 is formed on the surface 3a of the protective layer 3 on the dielectric layer 1 side. 3a is formed on substantially the entire surface. In addition, the ground terminal pattern 6a on the surface 3a.
At the position corresponding to 6b, one end is connected to the ground electrode pattern 5.
Ground terminal patterns 8a and 8b are formed in which the other end is connected to side surface A or side surface B of the bandpass filter. The earth terminal pattern 6a and the earth terminal pattern 8a are connected to the external earth electrode 9a, the earth terminal pattern 6b and the earth terminal pattern 8b are connected to the external earth electrode 9b, the extraction electrode pattern 7a is connected to the external extraction electrode 10a, and the extraction electrode pattern 7b is an external electrode 10b
are connected to each. Both external earth electrodes 9a mentioned above
-9b and both externally extracted electrodes 10a and 10b have a U-shaped cross section and are formed on the side surface of the bandpass filter. Here, a bandpass filter having the above structure was manufactured using the following procedure. First, a pattern as shown in FIG. 4 (the coil electrode patterns 41, 42 and both terminal patterns 6a, 6b, 7a, 7b) is formed on one main surface of the dielectric sheet 101 (thickness of approximately several tens of μm) shown in FIG. Apply copper paste or the like so that the pattern is the same as 12). Meanwhile, in parallel with this, a pattern as shown in FIG. 5 (the earth electrode pattern 5 and the same pattern as the ground terminal patterns 8a and 8b) Copper paste or the like is applied so as to form a pattern 13. Next, as shown in FIGS. 6 and 7, the dielectric sheet 1
01 through the sheet layer 16, the pattern 12 is
The protective sheet 2, the sheet layer 16, and the protective sheet 11 (protective sheet 2
and similar structure) are laminated in order and further crimped to form a laminate 1.
5. After this, the parts corresponding to the exposed parts 17a, 17b to 19a, 19b of the paste layer shown in FIG.
As shown in FIG. 9, copper paste or the like is printed or applied on the paste layers 20a, 20b, 21a,
21b is produced. Thereafter, the laminate is fired to integrate the dielectric sheets, thereby producing a bandpass filter. Incidentally, the firing of the laminate and the baking of the paste layers 20a, 20b, 21a, and 22a are as follows:
It may be performed in a separate process. Incidentally, although the bandpass filter manufactured as described above does not have a capacitor pattern formed therein, it has an equivalent circuit as shown in FIG. 10 (M in the figure indicates magnetic coupling). this is,
This is due to the following two reasons. ■Coil electrode pattern 4
1 and 42 are at the same potential as the ground electrode pattern 5 (that is, in a grounded state). ■Coil electrode pattern 4
A dielectric layer 1 is provided between 1 and 42 and the ground electrode pattern 5.
is present, so stray capacitance occurs. In this way, a capacitor is formed, and since the pattern pieces 41d and 42c of the coil electrode patterns 41 and 42 are magnetically coupled as described above, it has an equivalent circuit as shown in FIG. . In addition, since the above-mentioned stray capacitance mainly occurs between the coil electrode patterns 41 and 42 and the ground electrode pattern 5,
2 and the ground electrode pattern 5 are moved closer to each other or separated from each other, the capacitance of the capacitor changes, and the frequency of the pass band can be changed. Specifically, if the coil electrode patterns 41 and 42 and the ground electrode pattern 5 are brought closer together (reducing the number of dielectric sheets 101), the capacitor capacity increases, so the frequency of the passband becomes lower, while the coil If the electrode patterns 41 and 42 and the ground electrode pattern 5 are separated (by increasing the number of dielectric sheets 101),
Since the capacitance of the capacitor becomes smaller, the frequency of the passband becomes higher. Further, the stray capacitance can also be changed by changing the dielectric constant of the dielectric layer 1 and the thickness of the coil electrode patterns 41 and 42. For example, the coil electrode pattern 41.
If the width L2 of 42 is increased, the stray capacitance becomes larger and the frequency of the passband can be lowered, so that the device can be further miniaturized. However, pattern pieces 41a and 41
b, between pattern pieces 41c and 41d, pattern piece 42a
- If the spacing between the pattern pieces 42b and the pattern pieces 42c and 42d becomes too narrow, the waveform will deteriorate, so it is not preferable to make the width L2 of the coil electrode patterns 41 and 42 wider than necessary. Further, the bandwidth of the bandpass filter is changed by changing the distance L6 between the pattern pieces 41d and 42c. Specifically, narrowing the distance L6 widens the bandwidth, while widening the distance L6 narrows the bandwidth. However, if the distance L6 is made narrower than necessary, a bimodal characteristic will result, which is not preferable. The input/output impedance can be changed by changing the distance L7 between the ground terminal pattern 6a and the extraction electrode pattern 7a, or by changing the ground terminal pattern 6b.
This is done by changing the distance L8 between the electrode pattern 7b and the extraction electrode pattern 7b. According to experiments, by adjusting the dielectric constant and thickness of the dielectric layer 1 or the area of the coil electrode pattern 4, the applicable frequency of the bandpass filter of the present invention can be adjusted to several
00MHz to several GHz. An example of this is shown in the experiment below. [Experiment] The frequency characteristics of the bandpass filter having the above structure were investigated, and the results are shown in FIG. [Other matters] ■ When mounting the bandpass filter of the present invention, the bandpass filter of the present invention should be mounted with the electrodes on the printed circuit board aligned with the external earth electrodes 9a and 9b and the external lead-out electrodes 10a and 10b. Place the filter on the
All you have to do is solder. At this time, the outer side is the protective layer 2 and 3.
Since the coil electrode patterns 41 and 42 are covered with
This can prevent the ground electrode pattern 5 from being damaged. (2) The dielectric layer 1 is not limited to a structure in which a plurality of thin dielectric sheets 101 are stacked, but a dielectric sheet formed in advance to a predetermined thickness may be used. ■It is not necessary to manufacture the products of the present invention one by one; multiple coil electrode patterns 41 and 42 are formed on one wide dielectric sheet, and the same number of ground electrode patterns 5 are formed on the same dielectric sheet. However, a method may also be used in which the materials in this state are laminated and then cut into pieces one by one and then fired. (Second Embodiment) A second embodiment of the present invention is shown in FIGS. 12 and 1.
The following explanation will be given based on 3. FIG. 12 shows the second embodiment of the present invention.
FIG. 13 is a plan view of main parts of the bandpass filter according to the embodiment.
is a graph showing the frequency characteristics of the bandpass filter shown in FIG. 12. Incidentally, members having the same functions as those in the first embodiment are given the same numbers, and their explanations will be omitted. This also applies to the following examples. As shown in FIG. 12, the ends of the pattern pieces 41d and 42c are connected to the ends of the pattern pieces 41a and 42a, respectively (i.e.,
The structure is the same as that of the first embodiment described above except that the gap portions 30 and 31 are not formed. [Experiment] The frequency characteristics of the bandpass filter having the above structure were investigated, and the results are shown in FIG. (Third Embodiment) A third embodiment of the present invention is shown in FIGS. 14 and 1.
5 will be explained below. FIG. 14 shows the third embodiment of the present invention.
FIG. 15 is a plan view of main parts of the bandpass filter according to the embodiment.
is a graph showing the frequency characteristics of the bandpass filter shown in FIG. 14. As shown in FIG. 14, the gap 30 of the coil electrode pattern 41 is separated between the pattern piece 41a and the pattern piece 4.
1c, the configuration is similar to that of the first embodiment. [Experiment] The frequency characteristics of the bandpass filter having the above structure were investigated, and the results are shown in FIG. (Fourth Embodiment) A fourth embodiment of the present invention is shown in FIGS. 16 and 1.
7 will be explained below. FIG. 16 shows the fourth embodiment of the present invention.
FIG. 17 is a plan view of the main parts of the bandpass filter according to the embodiment.
is a graph showing the frequency characteristics of the bandpass filter shown in FIG. 16. As shown in FIG. 16, the gap 30 of the coil electrode pattern 41 is separated between the pattern piece 41a and the pattern piece 4.
1c, and the gap 31 of the coil electrode pattern 42 is formed between the pattern piece 42b and the pattern piece 42d. [Experiment] The frequency characteristics of the bandpass filter having the above structure were investigated, and the results are shown in FIG. (Fifth Embodiment) The fifth embodiment of the present invention is shown in FIGS. 18 to 20.
The following explanation is based on the following. 18 and 19 are diagrams showing a bandpass filter according to a fifth embodiment of the present invention, in which FIG. 18 is an exploded perspective view, FIG. 19 is a plan view of main parts, and FIG.
is a graph showing the frequency characteristics of the bandpass filter shown in FIGS. 18 and 19. FIG. As shown in FIGS. 18 and 19, the structure is the same as that of the first embodiment, except that the shapes of the coil electrode patterns 41 and 42 are different. Specifically, linear pattern pieces 41e arranged opposite to each other in the horizontal direction
・41f and pattern pieces 42e and 42f are respectively,
These pattern pieces 41e, 41f and pattern piece 42e
- Straight pattern piece 41 connected to one end of 42f
g and pattern piece 42g. and,
One end of the pattern piece 41e is connected to a ground terminal pattern 6a extending to the B end face and an extraction electrode pattern 7a, and one end of the pattern piece 42e is connected to a ground terminal pattern extending to the A end face. The structure is such that the pattern 6b and the extraction electrode pattern 7b are connected. [Experiment] The frequency characteristics of the bandpass filter having the above structure were investigated, and the results are shown in FIG. (Sixth Embodiment) A sixth embodiment of the present invention is shown in FIGS. 21 to 26.
The following is an explanation based on the following. Figure 21, Figure 23, Figure 25
is an exploded perspective view of a bandpass filter according to a sixth embodiment of the present invention, and FIGS. 22, 24, and 26 are graphs showing frequency characteristics of the bandpass filters shown in FIGS. 21, 23, and 25, respectively. As shown in FIG. 21, FIG. 23, and FIG. 25, the dielectric layer 1 and the ground electrode pattern 5 are sequentially provided not only on one side but on both sides of the coil electrode patterns 41 and 42, respectively. , the structure is similar to that of the third embodiment and the fourth embodiment. [Experiment] The frequency characteristics of the bandpass filter having the above structure were investigated, and the results are shown in FIGS. 22, 24, and 26, respectively. As is clear from FIGS. 22, 24, and 26, it is recognized that the passband frequency of the bandpass filter is slightly lower. This is thought to be due to the fact that stray capacitance is formed not only on one side but on both sides of the coil electrode patterns 41 and 42, so that the capacitance of the bandpass filter increases. Although not shown in the above embodiments, it has been experimentally confirmed that the same effects as those described above can be obtained even when the bandpass filters shown in the second and fifth embodiments have the same structure. . (Seventh Embodiment) The seventh embodiment of the present invention is shown in FIGS. 27 and 2.
8 will be explained below. 27 and 28 are diagrams showing a bandpass filter according to a seventh embodiment of the present invention, in which FIG. 27 is an exploded perspective view and FIG. 28 is a plan view of essential parts. As shown in FIGS. 27 and 28, the configuration is the same as that of the bandpass filter shown in FIG. 21 of the sixth embodiment, except that the shape of one of the ground electrode patterns (the upper pattern in FIG. 27) is different. be. Specifically, the ground electrode pattern 5 is divided into two, and each pattern 51.
52 is configured to be one size larger than the coil electrode patterns 41 and 42, and each ground electrode pattern 51 and 52 has a ground terminal pattern 8a and 8b, respectively.
The structure is such that the two are connected. With such a configuration, the stray capacitance can be adjusted by simply cutting a portion of the ground electrode patterns 51 and 52 corresponding to the pattern pieces 41d and 42c (for example, the portion indicated by the two-dot chain line C in FIG. 27). Therefore, the frequency can be easily adjusted. Although the above adjustment is possible with the ground electrode patterns of the first to fifth embodiments (formed almost on the entire surface), the cutting length becomes longer, so it is difficult to adjust the frequency. For example, it is desirable to adopt the configuration of this embodiment. Also,
The ground electrode pattern of this embodiment is not limited to the bandpass filter having the structure shown in FIG. 21 of the sixth embodiment, but can also be applied to those shown in other embodiments. (Eighth Embodiment) An eighth embodiment of the present invention will be described below based on FIG. 29. FIG. 29 is an exploded perspective view of a bandpass filter according to an eighth embodiment of the present invention. As shown in FIG. 29, on the dielectric sheet 101 adjacent to the dielectric sheet 101 on which the coil electrode patterns 41 and 42 are formed,
The structure is similar to that of the bandpass filter of the sixth embodiment shown in FIG. 21, except that floating electrode patterns 33 and 34 having the same shape as the coil electrode patterns 41 and 42 are formed. Although not shown in the drawings, by adopting such a structure, the bandpass filter of the sixth embodiment shown in FIG.
It has been confirmed through experiments that the frequency peak of the passband becomes even lower. This is the coil electrode pattern 41
This is thought to be due to the fact that stray capacitance is formed between 42 and the floating electrode patterns 33 and 34, which increases the capacitance of the bandpass filter. [Other matters] The structure of the coil electrode patterns 41 and 42 is not limited to those shown in the various embodiments above, and may be loop-shaped as shown in FIGS. 30 and 31, for example. .

[Effects of the Invention] As explained above, according to the present invention, the Q can be dramatically improved because of the so-called strip line structure and because the pattern pieces of the first electrode are not adjacent to each other. becomes possible. As a result, the insertion loss of the bandpass filter is reduced, and the skirt characteristics become sharper. Furthermore, since the first electrode has a loop shape, the dimensions of the element are reduced. In addition, the impedance can be adjusted by simply changing the distance between the lead terminal of the first electrode and the ground terminal, making it extremely easy to adjust the impedance. For these reasons, it is possible to provide an extremely excellent bandpass filter that has low insertion loss, is compact, and has input and output impedances that can be adjusted arbitrarily.

[Brief explanation of drawings]

FIG. 1 is a plan view of a bandpass filter according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view of a bandpass filter according to a first embodiment of the present invention.

FIG. 3 is a plan view of a dielectric sheet used in the present invention.

4 is a plan view showing a state in which a coil electrode pattern is formed on the dielectric sheet of FIG. 3; FIG.

5 is a plan view showing a state in which a ground electrode pattern is formed on the dielectric sheet of FIG. 3; FIG.

FIG. 6 is a front view when dielectric sheets are laminated.

FIG. 7 is a side view of stacked dielectric sheets.

FIG. 8 is a front view when the laminate is crimped.

FIG. 9 is a front view when external electrodes are formed.

10 is an equivalent circuit diagram of the bandpass filter shown in FIG. 1. FIG.

11 is a graph showing frequency characteristics of the bandpass filter shown in FIG. 1. FIG.

FIG. 12 is a plan view of essential parts of a bandpass filter according to a second embodiment of the present invention.

13 is a graph showing frequency characteristics of the bandpass filter shown in FIG. 12. FIG.

FIG. 14 is a plan view of essential parts of a bandpass filter according to a third embodiment of the present invention.

15 is a graph showing frequency characteristics of the bandpass filter shown in FIG. 14. FIG.

FIG. 16 is a plan view of essential parts of a bandpass filter according to a fourth embodiment of the present invention.

17 is a graph showing frequency characteristics of the bandpass filter shown in FIG. 16. FIG.

FIG. 18 is an exploded perspective view of a bandpass filter according to a fifth embodiment of the present invention.

FIG. 19 is a plan view of essential parts of a bandpass filter according to a fifth embodiment of the present invention.

20 is a graph showing frequency characteristics of the bandpass filter shown in FIGS. 18 and 19. FIG.

FIG. 21 is an exploded perspective view of a bandpass filter according to a sixth embodiment of the present invention.

22 is a graph showing frequency characteristics of the bandpass filter shown in FIG. 21. FIG.

FIG. 23 is an exploded perspective view of a bandpass filter according to a modification of the sixth embodiment.

24 is a graph showing frequency characteristics of the bandpass filter shown in FIG. 23. FIG.

FIG. 25 is an exploded perspective view of a bandpass filter according to another modification of the sixth embodiment.

26 is a graph showing frequency characteristics of the bandpass filter shown in FIG. 25. FIG.

FIG. 27 is an exploded perspective view of a bandpass filter according to a seventh embodiment of the present invention.

FIG. 28 is a plan view of essential parts of a bandpass filter according to a seventh embodiment of the present invention.

FIG. 29 is an exploded perspective view of a bandpass filter according to an eighth embodiment of the present invention.

FIG. 30 is a plan view of a main part showing a modification of the bandpass filter of the present invention.

FIG. 31 is a plan view of main parts showing another modification of the bandpass filter of the present invention.

FIG. 32 is an explanatory diagram showing a conventional stripline dielectric resonator.

FIG. 33 is an explanatory diagram showing a conventional stripline dielectric resonator.

FIG. 34 is an explanatory diagram showing a conventional coil pattern dielectric resonator.

[Explanation of symbols]

1 Dielectric layer 5 Earth electrode pattern 6a　Earth terminal pattern 6b Ground terminal pattern 7a Exit electrode pattern 7b Extraction electrode pattern 8a　Earth terminal pattern 8b Ground terminal pattern 33 Floating electrode pattern 34 Floating electrode pattern 41 Coil electrode pattern 42 Coil electrode pattern 101 Dielectric sheet

Claims (4)

[Claims] Claim 1: A bandpass filter, in which two first electrodes are arranged on one main surface of a plate made of a dielectric material, and a second electrode is arranged on the other main surface. Both of the first electrodes have a loop shape, and each of the first electrodes is arranged in a magnetically coupled state, and one of the first electrodes is arranged in a magnetically coupled state.
an extraction terminal and a ground terminal drawn out from the electrode toward the end of the plate at intervals having a predetermined impedance; and an interval having a predetermined impedance from the other first electrode toward the end of the plate. A band pass characterized in that an extraction terminal and a ground terminal are drawn out to different sides, the second electrode has a planar shape, and the ground terminal is drawn out toward an end of the plate body. filter. 2. Two first electrodes are arranged between one main surface of two plates made of a dielectric material, while at least one of the other main surfaces of the two plates is arranged between two first electrodes. This is a bandpass filter in which second electrodes are respectively arranged on the main surface, the first electrodes are arranged in a loop shape, each of the first electrodes is arranged in a magnetically coupled state, and one of the first electrodes is arranged in a loop shape. A take-out terminal and a ground terminal are drawn out from the first electrode toward the end of the plate body at intervals having a predetermined impedance, and a predetermined impedance is drawn from the other first electrode toward the end of the plate body. The extraction terminal and the ground terminal are drawn out at different intervals, and the second electrode has a planar shape, and the ground terminal is drawn out toward the end of the plate. bandpass filter. 3. Two first electrodes are disposed between one main surface of two plates made of dielectric material, while a second electrode is disposed on the other main surface of the two plates. A bandpass filter in which electrodes are respectively arranged, the first electrodes both forming a loop shape, each of the first electrodes being arranged in a magnetically coupled state, and from one first electrode to the above. An extraction terminal and a ground terminal are drawn out at intervals having a predetermined impedance toward the end of the plate, and an extraction terminal is drawn out from the other first electrode at intervals having a predetermined impedance toward the end of the plate. The terminal and the ground terminal are drawn out to different sides, and furthermore, at least one of the second electrodes is divided into two so that it has a slightly larger shape than the first electrode, and A bandpass filter characterized in that each ground terminal is drawn out toward the end of the plate. 4. A third electrode having the same shape as the first electrode is formed between the first electrode and at least one of the second electrodes. Section 3
Bandpass filter as described.