JP4150809B2 - Bandpass filter for GHz band - Google Patents

Description

The present invention relates to a band-pass filter for GHz band used in a frequency region of several hundred MHz to several tens of GHz.

Today, radio waves in the frequency range of several hundred MHz to several tens of GHz are favorably used for familiar wireless communication means. For example, an 800 MHz (0.8 GHz) band or 1.5 GHz band for a cellular phone, a 1.9 GHz band for a PHS, a 5.8 GHz band for an ETC (automatic toll collection) device on a highway, and 2. for a wireless PAN. The band allocation is 4 GHz band or 5.2 GHz band, and 5.8 GHz band for DSRC (narrow band communication).

All of these frequency-domain radio waves are used in connection with the operation of automobiles or are highly likely to be received, so they are received by the same antenna, digitally processed and used together. Is being planned. Even in such a case, or when using radio waves of each frequency band alone, in order to process the data by cutting the noise caused by harmonics and reflected waves, it is necessary to have a predetermined bandwidth in each band. A band-pass filter that passes only the signal and cuts other signals is required.

The applicant has developed and put to practical use various electromagnetic shielding materials in which a soft magnetic substance powder is dispersed in a rubber or plastic matrix. The inventor has invented and already disclosed a low-pass (high-cut) filter using the electromagnetic wave absorbing shield material (Patent Document 1). The filter is a chip type, and in contact with a rectangular dielectric surface, one signal line made of a conductor and at least one GND line are parallel on one surface or front and back. It is characterized in that an electromagnetic wave absorber in which a soft magnetic substance powder is dispersed in a synthetic resin matrix is used as the dielectric. The product of the example shows an insertion loss of −5 dB for a high frequency of 1 GHz or more.
JP 2002-171104 A

The basic object of the present invention is for the GHz band having a sharp low-cut-high-cut characteristic, which is used in the frequency region of several hundred MHz to several tens of GHz, utilizing the knowledge of the above-described low-pass filter disclosed by the applicant. It is to provide a bandpass filter. An additional object of the present invention is to provide a notch GHz bandpass filter having at least one notch in the passband in the above bandpass filter for GHz band.

The band-pass filter for GHz band of the present invention that achieves the above basic object is provided with a conductor on the surface of a magnetic loss sheet (1) in which soft magnetic metal powder is dispersed in a sheet-like polymer matrix. An input signal line (2) and an output signal line (3), which are formed of strips and run in series, are arranged with a gap therebetween, and opposite ends of both lines are connected via capacitance means, and the back surface of the sheet have a structure provided with the GND line (4) to,
Capacitance means is formed by providing an intermediate line (7) made of a conductor strip on the input signal line (2) and the output signal line (3) through an insulating film (6). The number of lower intermediate lines that are opposed to at least one lower intermediate line (71a,...) Existing on the magnetic loss sheet with the insulating film (6) interposed therebetween. And the number of upper intermediate lines (72a, 72b,...) Obtained by adding 1 to
Select the value of the capacitance of the capacitor formed by the intermediate line (7) to determine the low cut characteristics,
By selecting the area (length in the case of the same width) where the input signal line and the upper intermediate line, the upper intermediate line and the lower intermediate line, and the upper intermediate line and the output signal line overlap, the passing attenuation amount is maximized. The notch frequency is determined, and the frequency characteristics of the pass attenuation amount by a combination of the notch frequency, the particle shape of the soft magnetic metal powder constituting the sheet and the filling rate in the matrix, and the sheet shape and thickness, etc. Based on the above , determine the high cut characteristics,
By combining the low-cut characteristics and high-cut characteristic, and wherein the determining the passband of the bandpass filter.
[The invention's effect]

The band-pass filter for GHz band of the present invention uses a sheet obtained by dispersing soft magnetic metal powder in a sheet-like synthetic resin matrix as a base material, and "input signal line-capacitance means-output signal line" on the surface thereof. And having a GND line on the back surface has a high-frequency bandpass characteristic that allows a signal in a desired band to pass in a frequency range of several hundred MHz to several tens of GHz and cuts other high-frequency signals.

On the other hand, when another aspect of the present invention is employed as the capacitance means, an intermediate line that overlaps the input / output signal lines is employed instead of the capacitor, as shown in the embodiments described later, and the degree of overlap is determined. By selecting, in addition to the above bandpass performance, a notch effect that attenuates a specific frequency can be obtained. In the past, wideband bandpass filters and notch filters could only be configured by combining various low-pass circuits and high-pass circuits in multiple stages, or they could be solved circuitically by smoothing pulse signals. According to the present invention, a desired notch filter can be realized with a simple circuit.

Therefore, the high-frequency bandpass filter for GHz band according to the present invention contributes to the integration of the above-mentioned automobile-related communication devices including mobile phones, car navigation systems, and ETCs, and also in various fields, for example, for UWB transmission. It is expected to be a useful device.

Bandpass filter GHz band according to the present invention, the first principle embodiment, as shown in FIGS. 1 and 2, the magnetic loss obtained by dispersing a powder of a soft magnetic metal in the sheet-like polymeric matrix On the surface of the sheet (1), an input signal line (2) and an output signal line (3), which are made of a strip of conductors and run in series, are arranged with a gap, and opposite ends of both lines are capacitance means. Is a high-frequency bandpass filter having a configuration in which a GND line (4) is provided on the back side of the sheet, using a chip capacitor (5) as a capacitance means, and selecting a capacitance value thereof And the impedance determined by the length, width, thickness and shape of the lines of the input signal line (2) and the output signal line (3). The high-cut characteristics are determined by selecting the magnetic loss characteristics determined by the particle shape and the filling rate in the matrix of the soft magnetic metal powder constituting the magnetic loss sheet and the sheet shape and thickness. This is a bandpass filter characterized in that the passband is determined by combining the characteristics and the high cut characteristics.

As shown in FIGS. 3 and 4, the second principle mode is that a conductor strip is formed on the surface of a magnetic loss sheet (1) obtained by dispersing soft magnetic metal powder in a sheet-like polymer matrix. The input signal line (2) and the output signal line (3) that run in the series direction are arranged with a gap therebetween, and the opposite ends of both lines are connected via a capacitance means, and a magnetic loss sheet ( 1) A high-frequency bandpass filter having a configuration in which a GND line (4) is provided on the back surface of 1), wherein a capacitance means is placed on an input signal line (2) and an output signal line (3) with an insulator film ( 6), an intermediate line (7) consisting of another strip of conductor is provided so as to overlap both the input signal line and the output signal line. Between the output line and the intermediate line, and by generating capacitance between the output signal line and the intermediate line, selecting the value of the capacitance to determine the low-cut characteristics, and The input signal line (2) and the output signal line (3) are selected from impedances determined by the length, width, thickness and shape of the line, and the particle shape and matrix of the soft magnetic metal powder constituting the magnetic loss sheet filling factor in, as well as to determine the high-cut characteristic by selecting the magnetic loss characteristics defined by the shape and thickness of the sheet, and wherein the determining the passband by combining the low-cut characteristics and high-cut characteristic, GHz This is a band-pass filter for bands.

In the embodiment shown in FIGS. 3 and 4 of the band-pass filter for GHz band of the present invention, the length of the portion where the input signal line (2) and the intermediate line (7) overlap, and the output signal line (3) By selecting the length of the portion where the intermediate line (7) overlaps, the capacitance value of the capacitor formed by each can be adjusted. Needless to say, the capacitance of the capacitor is determined by the area of the overlapping portion and the mutual distance. In FIG. 3, since the overlapping portions have the same width, the area is determined by the length.

Here, since the distance between the intermediate line and the input / output signal line is determined by the thickness of the insulating film (6), if a certain thickness is assumed, the capacitance will be influenced. The thing is the area of the overlapping part. It will be readily understood that the area of the overlapping portion is also determined solely by the overlapping length if the input and output signal lines, which are strips of conductors, and the intermediate line have a constant and constant width. If the area of the overlapping parts is the same, the capacitance is naturally determined by the dielectric constant and thickness of the insulator, and the bandpass characteristics can be changed by adjusting the thickness of the insulator. Will be obvious as well.

In this case, the two overlapping portions may have substantially the same area so that the capacitances of the two capacitors are the same, or the capacitances of the two capacitors are different from each other by having different sizes. It may be. As will be described later in the embodiment, the pass band and further the notch filter characteristic are determined by combining the selection of the capacitance value and the selection of the impedance of the input signal line and the output signal line.

In the example shown in FIG. 3 and FIG. 4 for the second aspect described above, there is one intermediate line that extends over the input signal line and the output signal line. Variations in the form of circuits employed in the invention are also possible. More specifically, as illustrated in FIG. 8, the intermediate line (7) is replaced with one lower intermediate line (72) existing on the magnetic loss sheet, and an insulator film (6). This is a modified embodiment composed of a set of three conductor pieces with two upper intermediate lines (71a, 71b) facing each other. As will be understood from this description, the middle line (7) can also consist of two lower middle lines and three upper middle lines. Examples are shown in later examples and FIG.

As can be understood from the above description, the high-frequency bandpass filter of the present invention provides low cut by the capacitance means, and high cut by the impedance of the input signal line-intermediate line-output signal line, and the soft magnetic metal powder. Is caused by the magnetic loss of the magnetic loss sheet formed by dispersing the resin in the sheet-like synthetic resin matrix. The impedance of the input signal line-intermediate line-output signal line is determined by the length, width, thickness and shape of the line, and the magnetic loss characteristics of the magnetic loss sheet (1) are mainly dispersed in the synthetic resin matrix. It is determined by the particle size of the soft magnetic metal powder and the filling rate in the matrix. The band to be passed by the band-pass filter is a combination of the high cut characteristic and the low cut characteristic, so the design is performed for each.

As described above, the high-frequency bandpass filter according to the present invention can obtain a notch effect in which a specific frequency is attenuated in a frequency range to be passed, and the notch frequency at which the pass attenuation amount of the notch filter is maximum is As described above, it is possible to control the intermediate line by adjusting the length of the conductors that are overlapped with each other with the insulator therebetween.

As a soft magnetic metal powder, a metal selected from Sendust, Fe, Fe-Si alloy, Fe-Ni alloy, Fe-Co alloy, Fe-Cr alloy, Fe-Cr-Al alloy, and Fe-Cr-Si alloy It is preferable to select a powder having an average particle diameter of 30 μm or less. A powder having an average particle size larger than 30 μm is disadvantageous in obtaining high cut characteristics because the sheet does not exhibit high magnetic permeability. The metal powder having a small average particle diameter as described above can be produced by atomizing a molten metal and subsequently performing classification if necessary.

As the synthetic resin used as the matrix of the magnetic loss sheet, those selected from nylon, polyphenylene sulfide, epoxy resin, and liquid crystal polymer (LCP) are preferable. In addition, a wide range of thermoplastic or thermosetting synthetic resins that can be molded by injection molding or extrusion molding can be used. Examples thereof include nylon, polyethylene, polypropylene, and phenol resin. The sheet-like body is advantageously formed by injection molding the kneaded product of the soft magnetic metal powder and the synthetic resin into a sheet-like body having a predetermined length.

Alternatively, the sheet can be formed by dispersing a soft magnetic powder in a curable liquid polymer and then curing the polymer liquid.

As described above, the characteristics of the magnetic loss sheet that are important for the high-cut characteristics of the high-frequency bandpass filter of the present invention are determined by the magnetic permeability and the dielectric constant of the magnetic loss sheet. It is the particle size and filling rate of the magnetic metal powder, and the sheet thickness. Generally speaking, at the same filling rate, the smaller the particle size, the higher the cutting frequency, and the same particle size, the higher the filling rate, the lower the tendency to cut the frequency There is.

The filling rate of the soft magnetic metal powder in the magnetic loss sheet is a factor that determines the thickness of the sheet to be used. The thinner the sheet thickness, the higher the cut frequency. Other factors include the flatness of the soft magnetic metal powder, but the flat powder is not very suitable on the high frequency side.

It has been found that the input signal line-intermediate line-output signal line impedance has an influence on the frequency at which the high cut is performed, and in particular, the length of the line has a great influence. The shorter the line, the higher the cut frequency. In practicing the present invention, the band-pass filter for the GHz band should be designed in consideration of the factors as described above.

The high-cut characteristics are difficult to express numerically for each factor, and often have to be determined empirically, but by supplementing some experiments as necessary with reference to the examples described later. Those skilled in the art should be able to arbitrarily control the high-cut characteristics of the high-frequency bandpass filter to be realized. In any case, the low-pass filter using the magnetic loss sheet containing the soft magnetic metal powder has frequency characteristics as shown in FIG.

In order to form the input / output signal lines of the high-frequency bandpass filter of the present invention, various methods such as etching (patterning) of a flexible substrate, pattern printing of conductive ink, metal plating or sputtering can be employed. The same applies when an intermediate line is provided. Of course, there is no problem in forming the input / output signal lines and the intermediate lines by different methods. The thickness of the signal line must be determined in consideration of the resistance value allowed for the circuit and the reliability of the circuit, and a foil with a thickness of several tens of μm is used in terms of ease of manufacturing work. Although there is a possibility of several μm in terms of performance. Therefore, when the mass production of the same standard is reached, a production method suitable for mass production may be selected and a thickness advantageous for the production method may be determined.

The capacitor shown in FIGS. 1 and 2 is a chip-type multilayer ceramic capacitor as a capacitor of the band-pass filter for GHz band. Since off-the-shelf products with various capacities and pressure resistances are commercially available, they can be arbitrarily selected and used. The low cut characteristic of a circuit including a capacitor is easier to formulate than the high cut characteristic. Now, considering FIG. 6 as an equivalent circuit of the low-cut component in the high-frequency bandpass filter of the present invention, the expression representing the attenuation A (ω) is as shown in the following expression 1, which is a curve of the form shown in FIG. .
[Formula 1]
A (ω) = Vout / Vin = R / {(1 / jωC) + R} = jωRC / (1 + jωRC)

Now, to obtain -3 dB attenuation, that is, 20 log ₁₀ {A (ω)} =-3 dB, A (ω) = √ (1/2).
ωRC = 2πf _c RC = 1
Get. f _c = 1 GHz (1000 MHz), R = 50Ω
Then, C≈3 pF.

3 and 4, that is, the high-frequency bandpass filter for the GHz band having an intermediate line, as described above, the length of the overlap between the intermediate line (7) and the input signal line (2), and The characteristics are influenced by the overlap length of the intermediate line (7) and the output signal line (3), and the degree of attenuation is increased at a specific frequency, and the performance as a notch filter is exhibited. The inventors investigated how the line overlap length L (mm) affects the notch frequency f (GHz), as shown in the reference examples and examples described later, and experimentally obtained a relational expression. Derived. By referring to these data and adding some experiments as necessary, a bandpass notch filter for the GHz band having a desired frequency characteristic can be realized.
[ Reference Example 1]

As the soft magnetic metal powder, Fe powder having an average particle diameter of 1.6 μm was used. A liquid crystal polymer was selected as the matrix material. The powder was filled and kneaded so that the filling rate was 10% by volume, and extruded from a die to obtain a magnetic loss sheet (1) having a thickness of 1 mm. A rolled copper foil (thickness 35 μm) was bonded to the back surface to provide a lining to be a GND line (4), and the whole was cut into strips having a width of 20 mm and a length of 50 mm. On the other hand, on the surface, two ribbons of the same rolled copper foil with a width of 2.0 mm and a length of 24 mm are disposed and bonded from both ends toward the center, and the input signal line (2) and the output signal line (3 ). A bandpass filter for the GHz band with the configuration shown in FIG. 1 is manufactured by bonding a chip capacitor (5) (chip type multilayer ceramic type, manufactured by Matsushita Electric) with a conductive adhesive across the central gap. did.

Using this “high frequency bandpass filter”, the insertion loss over the frequency range from 0.1 GHz (100 MHz) to 10 GHz was measured using a “network analyzer” (manufactured by Japan HP), and the graph of FIG. 9 was obtained. . According to this graph, the manufactured high-frequency bandpass filter gives an attenuation of -3 dB or more to a signal of 1 GHz or less and 3.3 GHz or more, and therefore a high frequency intended to pass a band of approximately 1 to 3 GHz. It is useful as a bandpass filter.
[ Reference Example 2]

The copper foil lining produced in Reference Example 1, that is, a sheet with a GND line (4) and having a width of 20 mm and a length of 50 mm was fixed on a phosphor bronze plate having a thickness of 5 mm for stability. A substrate obtained by etching from a flexible substrate (25 μm thick polyimide film + 35 μm thick copper foil, which is an insulator) is attached to the center in the longitudinal direction, and a copper film having a thickness of 35 μm × width 1.5 mm is attached. The input signal line (2) and the output signal line (3) were formed so that two ribbons existed at both ends with a distance of 1.0 mm. A double-sided adhesive tape with adhesive applied to both sides of a 25 μm-thick polyimide tape to be the insulator (6) is attached to it, and an intermediate line (7) made of copper foil with a width of 1.5 mm is further adhered. A band-pass filter for the GHz band having the mode shown in FIGS. 3 and 4 was manufactured.

The intermediate line (7) has an equal length on both sides with the gap of 1.0 mm, that is, between the intermediate line and the input signal line, and between the intermediate line and the output signal line. The length of one side of the superposition was changed from 12.5 mm to 2.5 mm increments to increase it to 45 mm.

The insertion loss S21 (dB) was measured over the range of 0.1 to 10 GHz for the prototype bandpass filter for GHz band. In the graph, plot the relationship between the frequency and insertion loss and the one-sided overlap length at the first position where the peak of the transmission coefficient starts from the lower frequency side (hereinafter referred to as “First Frequency”). Thus, the graph shown in FIG. 10 was obtained. The overlap length of the entire line is twice the overlap length on one side, and the relationship between the line overlap length and the first frequency is plotted to obtain the graph shown in FIG. From this graph, the following expression 2 was obtained as a relational expression between the notch frequency f [GHz] and the line overlap length L [mm].
[Formula 2]
f [GHz] = 75 × 1 / (k × L [mm])
(Here, k is a coefficient determined by the metal powder filling rate, the particle size, the material, etc. of the sheet, strictly speaking, the complex relative permeability and the complex relative permittivity. In the sheet of this embodiment, k = 0.354. is there.)

  Of the prototype bandpass filters, the frequency characteristics of the transmission coefficient for graphs with overlapping lengths of 10 mm, 30 mm, 50 mm, 70 mm and 90 mm are as shown in FIG. A notch effect in which the attenuation becomes significant at the frequencies shown in Table 1 was observed.

［参考例３］
Table 1

[ Reference Example 3]

In Reference Example 2, the length that the intermediate line (7) overlaps with the input signal line (2) is kept constant at 4 mm, while the length that the intermediate line (7) overlaps with the output signal line (3) is 15 mm. From 5mm to 5mm, it was increased to 85mm.

  Here, the transmission coefficient S21 (dB) was measured over the range of 0.1 to 10 GHz for the prototype bandpass filter for the GHz band. The relationship between the first frequency and the transmission coefficient in the graph was plotted, and the graph shown in FIG. 13 was obtained. Of the prototype bandpass filters, the frequency characteristics of the transmission coefficient for graphs with one-side overlap lengths of 10 mm, 30 mm, 50 mm, 70 mm, and 85 mm are as shown in FIG. In response to this, a notch effect was observed, in which the attenuation became significant at the frequencies shown in Table 2, respectively.

［実施例］
Table 2

[Example]

By etching the flexible substrate used in Reference Example 2 (copper foil of a polyimide film + the thickness 35 [mu] m thick 25 [mu] m), a thickness of 35 [mu] m × width 1.0 mm, in as respective lengths shown in FIG. 15, Four copper ribbons were prepared in which the distance between the ends was as shown in FIG. Two sheets at both ends of the copper ribbon are respectively an input signal line (2) and an output signal line (3), and two sheets in the middle thereof are lower intermediate lines. By etching the same flexible substrate, three copper ribbons having the same thickness and width as described above, each having the same length as shown in FIG. The thing which is shown in is prepared. These copper ribbons become the upper middle line.

In still the same manner as in Reference Example 2, the copper foil lining sheet prepared in Reference Example 1 (width 20 mm, length 50 mm, GND with lines) those fixed by adhering on the phosphor bronze plate having a thickness of 5mm as substrate First, an etching sheet having the above four copper ribbons is attached to the substantially center in the longitudinal direction, and both sides of a polyimide tape having a thickness of 25 μm to be an insulator (6) are used. A double-sided adhesive tape to which an adhesive was applied was pasted. Then, the etching sheet having the three copper ribbons was pasted. In FIG. 15, the length of the overlapping portion of the “X” portion, that is, the overlapping portion of the input signal line (2) and the upper intermediate line (71) at the end of the intermediate line is 12.45 mm and 12.85 mm. Or it was changed to 13.25 mm.

For band-pass filter for GHz bands produced in the manner described above, in the same manner as in Reference Examples 1 to 3, over the range of 0.1～10GHz, it was measured transmission coefficient S21 [dB]. Among them, for three cases where X is 12.45 mm, 12.85 mm and 13.25 mm, the relationship between the value of X [mm] and the frequency [GHz] at which the notch effect occurs is as shown in Table 3. is there.

A graph of the frequency characteristics of S21 in the case of X = 12.45 mm is shown in FIG. This bandpass filter can be referred to as a “bandpass filter for 3 to 10 GHz band with a 5 GHz notch”. When this graph is overlaid with a graph of regulation values of UWB (Ultra Wide Band) EIRP (Equivalent Isotropically Radiated Power) radiation levels, FIG. 17 is obtained. From this graph, it is clear that the above restriction can be cleared by using the bandpass filter for the GHz band of the embodiment.

The top view which shows one reference example of the band pass filter for GHz band which makes the foundation of this invention. The longitudinal cross-sectional view of the II band direction of the bandpass filter for GHz bands of FIG. The top view which shows another reference example of the band pass filter for GHz band which forms the foundation of this invention. The longitudinal cross-sectional view of the II-II direction of the bandpass filter for GHz bands of FIG. The graph which shows the frequency characteristic of a low-pass filter using the magnetic loss sheet | seat which disperse | distributes the soft magnetic metal powder in a polymer matrix. The figure which shows the equivalent circuit of the high pass filter which uses a capacitor | condenser. The graph which shows the frequency characteristic of the attenuation | damping which the circuit of FIG. 6 gives to a signal. The longitudinal cross-sectional view similar to FIG. 2 and FIG. 4 which shows the change aspect of the bandpass filter for GHz bands of FIG. The graph which shows the frequency characteristic of the transmission coefficient measured about the bandpass filter for GHz bands manufactured by the reference example 1 of this invention. The graph which shows the relationship between a 1st frequency and insertion loss based on the data obtained by measuring about the bandpass filter for GHz bands manufactured by the reference example 2 of this invention. In the reference example 2 of this invention, the graph which derived the relational expression of line overlap length and a 1st frequency. The graph which shows the frequency characteristic of the insertion loss measured about the bandpass filter for GHz bands manufactured by the reference example 2 of this invention. The graph similar to FIG. 10 which shows the relationship between a 1st frequency and insertion loss based on the data obtained by measuring about the bandpass filter for GHz bands manufactured by the reference example 3 of this invention. The graph similar to FIG. 12 which shows the frequency characteristic of the insertion loss measured about the bandpass filter for GHz bands manufactured by the reference example 3 of this invention. The conceptual diagram which shows the overlap length of the input signal line, the output signal line, and the intermediate | middle line in the bandpass filter for GHz bands manufactured in the Example of this invention. The graph similar to FIG.9,12 and 14 which shows the frequency characteristic of the insertion loss of the bandpass filter for GHz bands manufactured in the Example of this invention. FIG. 17 is a graph in which the graph of FIG. 16 is superimposed on the UWB (Ultra Wide Band) EIRP (Equivalent Isotropically Radiated Power) radiation level standard.

Explanation of symbols

1 Magnetic Loss Sheet 2 Input Signal Line 3 Output Signal Line 4 GND Line 5 Chip Capacitor 6 Insulator Film 7 Middle Line 71 (71a, 71b, 71c) Upper Middle Line 72 (72a, 72b) Lower Middle Line X Input Signal Line Where the upper middle line overlaps

Claims (6)

An input signal line (2) and an output signal line (3 ) which are made of a conductor strip and run in series on the surface of a magnetic loss sheet (1) obtained by dispersing soft magnetic metal powder in a sheet-like polymer matrix. ) was placed with a gap, the ends facing each other of both lines are connected via the capacitance means, have a structure in which a GND line (4) on the back surface of the sheet,
Capacitance means is formed by providing an intermediate line (7) made of a conductor strip on the input signal line (2) and the output signal line (3) through an insulating film (6). The number of lower intermediate lines that are opposed to at least one lower intermediate line (71a,...) Existing on the magnetic loss sheet with the insulating film (6) interposed therebetween. And the number of upper intermediate lines (72a, 72b,...) Obtained by adding 1 to
Select the value of the capacitance of the capacitor formed by the intermediate line (7) to determine the low cut characteristics,
By selecting the area (length in the case of the same width) where the input signal line and the upper intermediate line, the upper intermediate line and the lower intermediate line, and the upper intermediate line and the output signal line overlap, the passing attenuation amount is maximized. The notch frequency is determined, and the frequency characteristics of the pass attenuation amount by a combination of the notch frequency, the particle shape of the soft magnetic metal powder constituting the sheet and the filling rate in the matrix, and the sheet shape and thickness, etc. Based on the above , determine the high cut characteristics,
A band-pass filter for a GHz band , wherein a pass band as a band-pass filter is determined by combining the low-cut characteristic and the high-cut characteristic. By selecting the area of at least a part of the overlapping portion of the input signal line and the upper intermediate line, the upper intermediate line and the lower intermediate line, and the upper intermediate line and the output signal line, the passing attenuation amount in the band pass band can be reduced. 2. The bandpass filter for GHz band according to claim 1, wherein a notch frequency that is maximum is set and has a notch filter characteristic for a specific frequency within the bandpass band. As a soft magnetic metal powder, a metal selected from Sendust, Fe, Fe-Si alloy, Fe-Ni alloy, Fe-Co alloy, Fe-Cr alloy, Fe-Cr-Al alloy and Fe-Cr-Si alloy, The bandpass filter for GHz band according to claim 1 or 2 , wherein powder having an average particle diameter of 30 µm or less is used. By using a resin selected from nylon, polyphenylene sulfide, epoxy resin and liquid crystal polymer (LCP) as a synthetic resin for the magnetic loss sheet (1) as a matrix, and injection molding a mixture with a soft magnetic metal powder , claim 1 or bandpass filter 2 GHz band, characterized in that is obtained by forming a predetermined length of the sheet. The GHz according to claim 1 or 2 , wherein the magnetic loss sheet (1) is formed by dispersing a soft magnetic powder in a curable polymer liquid and then curing the polymer liquid. Bandpass filter for bands. 3. The bandpass filter for GHz band according to claim 1 or 2 , wherein the signal line is formed by etching a flexible substrate, pattern printing with conductive ink, metal plating or sputtering.

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