JP2003229702A - Microstrip line and high-frequency filter substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-frequency filter substrate having reliable shielding effects and a structure by which the substrate can be easily mounted on a microstrip line, and to provide a microstrip line mounted with this substrate. <P>SOLUTION: In the microstrip line 200 mounted with the freely mountable high-frequency filter substrate 100 or the substrate 100 to be mounted, the front surface of the substrate 100 having a high-frequency filter circuit 102 is mounted on the front surface of the mounting part of the line 200, an input part 102(1) and an output part 102(5) of the line 200 are connected to a high-frequency strip line 202 of the line 200 side, and a grounding conductor 105 of the substrate 100 side is connected to a grounding conductor 205 of the mounting part side. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency filter substrate and a microstrip line in which a wearable high-frequency filter substrate is freely mounted to reduce high-frequency radiation and loss.

[0002]

2. Description of the Related Art In recent years, with the development of an advanced information society, a wireless LAN forming a wireless communication network in a certain area.
Communication systems that utilize satellite communication and communication base stations, such as systems (regional wireless communication networks) and cellular phone systems for mobile phones and car phones are expanding. In these communication systems, high frequency radio waves of 1 GHz (gigahertz) or higher such as microwave band and millimeter wave band are used as carriers.

High frequency filters such as low pass filters (LPFs), high pass filters (HPFs) and band pass filters (BPFs) used in these communication systems are usually designed as distributed constant circuits rather than lumped constant circuits. It

The lumped constant circuit is a circuit in which the physical shape of the elements forming the circuit is sufficiently smaller than the wavelength of the electric signal. In addition, the distributed constant circuit is a microstrip line.
(Microstrip line) is used.
In the distributed constant circuit using the microstrip line or the like, various wiring patterns having a length that is about the same as the wavelength of the electric signal or in the vicinity thereof are used as circuit elements of the high frequency filter.

Here, the microstrip line is an elongated strip line for high-frequency transmission (hereinafter referred to as a high-frequency strip line), which is made of a conductor such as metal such as copper on a substrate (surface) made of a dielectric material. ) Is provided and the grounded conductor is arranged on the back side of the substrate, the name of the distributed capacitance line.

An example of a distributed constant circuit using this microstrip line will be described below with reference to FIG.
FIG. 6 is a plan view showing a configuration of the bandpass filter (BPF) formed by planarly forming the high frequency stripline pattern. The BPF shown in FIG. 6 constitutes a filter circuit on the surface of a substrate 301 made of a dielectric material such as a printed circuit board or a ceramic substrate. This filter circuit
For example, it has a structure in which a plurality of high-frequency strip lines 302 (1) to 302 (5) having a minute width and made of a conductor such as a metal such as copper are arranged in parallel with each other with a predetermined gap therebetween.

The high frequency strip line 302 (1)
-302 (5) itself can be formed simultaneously in the wiring pattern forming step on the surface layer of the wiring substrate performed by the printing method or the lithography method.

In the filter circuit, adjacent high frequency strip lines 302 (1) to 302 (5) are arranged so that portions having a length of about one quarter of the high frequency wavelength λ desired to pass overlap each other. It is arranged so as to be offset in each longitudinal direction. And these high frequency strip lines 302
(2) to 302 (4) have a length of about one half of the high frequency wavelength λ desired to pass, and are designed to resonate with a signal of wavelength λ.

Here, when the wavelength of the radio wave in space is λ 0 and the effective permittivity of the substrate is ε _E , the wavelength λ to be passed is given by the following equation 1. λ = λ0 / √ε _Eー (1)

In such a BPF, the high frequency radio wave RF1 (wavelength λ) input from the end of the high frequency strip line 302 (1) is used.
In (0), while passing through the high-frequency strip lines 302 (1) to 302 (4) sequentially, the component of the wavelength λ of the wavelength λ0 to be passed is hardly attenuated. On the other hand, the resonance frequency (wavelength λ)
The wavelength components other than are attenuated and removed. Therefore, only the high frequency signal RF2 of the desired wavelength λ is output from the end of the high frequency strip line 302 (5).

However, in such a conventional BPF, since the high frequency strip lines 302 (1) to 302 (5) resonate with the signal of the desired wavelength λ, so to speak, they also function as a transmitting antenna. As a result, the high frequency strip line
302 (1) to 302 (5) also have a function of radiating a part of a signal having a desired wavelength λ to the outside as a radio wave. Therefore, BPF
In the conventional distributed constant circuit using the microstrip line, a part of the signal of the wavelength λ leaks to the outside as a radio wave, causing radiation loss.

This radiation loss tends to increase as the relative permittivity ε of the dielectric substrate decreases, the thickness t of the dielectric substrate increases, and the wavelength λ decreases. For example, when the relative permittivity ε is 4, the thickness t of the dielectric substrate is 0.51 mm, and the wavelength λ (frequency) is 24 GHz, the radiation loss of the conventional BPF is as large as about 3 dB.

Further, the high frequency strip line 302 (1)
302 (5) acts as a receiving antenna as well as the transmitting antenna. For this reason, even if another signal having an undesired wavelength λ enters from outside as a radio wave, it will be received. As a result, there is also a problem in that the received signals of the undesired wavelength λ are mixed with the originally necessary signals as spurious signals.

Therefore, in a distributed constant circuit using a microstrip line such as BPF, the periphery and the periphery of the filter circuit are shielded with a conductive metal or the like,
It is necessary to prevent the radiation loss and signal reception from the outside.

As such a shield, it is possible to enclose the filter circuit with a metal plate having an appropriate size. However, when the metal plate approaches the plane pattern of the filter circuit, the resonance frequency is lowered, and the frequency characteristics of the filter are deteriorated.
In order to prevent this and exhibit the above-mentioned shielding effect, it is necessary to place a metal plate or the like with a gap of 10 to 20 times the substrate thickness from the dielectric substrate. Therefore, this method has a problem that the outer size of the shield becomes large and the mounting cost becomes high.

For this reason, Japanese Patent Application Laid-Open No. 2000-252716 discloses a shield structure also called a triplate structure as shown in a perspective view in FIG. This shield structure includes a first substrate 411a made of a dielectric material and a pair of conductor patterns 415 formed on the first substrate 411a.
(1), 415 (2) and this pair of conductor patterns 415 (1), 415
The second substrate 411b is laminated on the first substrate 411a so as to sandwich (2). That is, it is a high frequency strip line in which a plane circuit pattern is provided between two ground conductors and a dielectric.

In the case of such a triplate structure,
Both sides of the planar circuit pattern are filled with a dielectric material, and the surrounding area is further shielded by a ground conductor. For this reason,
The radiation loss is significantly reduced and the reception of undesired signals is prevented without increasing the outer dimensions of the shield or increasing the mounting cost.

[0018]

However, the filter circuit having the triplate structure is a method of incorporating the filter structure in advance when the microstrip line itself is manufactured. Then, in this triplate structure, the planar circuit pattern is inevitably buried in the substrate. Therefore, in order to connect to the peripheral circuit, it is necessary to provide a connection portion via a through hole of the ground conductor and take out a signal to the surface layer of the substrate.

However, there is a problem that the radiation loss is inevitably generated in the connection portion necessary for extracting the signal and the frequency characteristic is distorted, so that the frequency characteristic as designed cannot be obtained. In addition, when the microstrip line itself is manufactured by adding the filter circuit having the triplate structure, it is more difficult to manufacture a printed circuit board composed of a plurality of layers with higher accuracy than in the normal microstrip line manufacturing. Therefore, the cost of manufacturing the microstrip line itself is significantly increased, and there is also a practical problem that it is not profitable unless it is manufactured in an excessively large amount.

The present invention has been made in consideration of these circumstances, and its purpose is to have a reliable shield effect and to be easily attached to a microstrip line, which is applicable, adaptable, and adaptable. (EN) Provided are a high frequency filter substrate having a rich structure, and a microstrip line provided with the high frequency filter substrate.

[0021]

In order to achieve the above-mentioned object, the subject matter of claim 1 of the present invention is a microstrip line on which a freely mountable high-frequency filter substrate is mounted. The substrate is a substrate made of a dielectric material, a high frequency strip line made of a conductor formed on the front surface of the substrate, an input section, an output section and a high frequency filter circuit formed on the high frequency strip line, and at least the back surface of the substrate. On the other hand, the microstrip line is formed on a substrate made of a dielectric material, a high frequency stripline made of a conductor formed on the front surface of the substrate, and at least a part of the back surface of the substrate. And a mounting part on which the high-frequency filter substrate is mounted. The front side of the high-frequency filter substrate is mounted on the front side of the mounting portion of the microstrip line, and the input section and the output section of the high-frequency filter board are connected to the high-frequency strip line on the microstrip line side, respectively. In addition, the ground conductor on the side of the high-frequency filter substrate is connected to the ground conductor on the side of the mounting portion.

Similarly, the subject matter of claim 2 of the high-frequency filter substrate of the present invention is a high-frequency filter substrate which can be mounted on the microstrip line of the above-mentioned claim 1, and is a substrate made of a dielectric material and formed on the substrate surface. A high frequency strip line made of a conductor, an input part, an output part and a high frequency filter circuit formed on the high frequency strip line, and a ground conductor formed on at least a part of the back surface of the substrate. is there.

In the present invention, as described above, the distributed constant circuit type high frequency filter substrate itself has a structure that can be mounted (mounted) on the surface of the parent substrate of the microstrip line body. At the same time, the high-frequency filter substrate and the microstrip line body are structured to have a reliable shield effect.

As a result, the radiation loss, which is a problem peculiar to the distributed constant circuit type high frequency filter using the microstrip line, is significantly reduced, and the reception of an undesired signal is prevented. Moreover, these effects can be realized without increasing the outer dimensions of the shield, increasing the attachment cost, and adversely affecting the microstrip line main body and the main body manufacturing.

The high-frequency filter substrate of the present invention may be mounted on an existing microstrip line body later and used, or may be mounted in advance when the microstrip line body is manufactured and used. Note that the configurations of the microstrip line and the high-frequency filter substrate of the present invention are not limited to the configurations of only the requirements described in the above-mentioned claims, and will be described in the following embodiments or otherwise, and are necessary for practical use. Naturally, addition of requirements and means is allowed.
Therefore, the meaning of "consisting" described in the above claims is meant to include each requirement recited in the claims, and does not mean to be configured only from each requirement recited in the claims. .

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. An embodiment of the high-frequency filter substrate of the present invention is shown in a perspective view in FIG. Further, FIG. 2 is a perspective view showing an embodiment of the microstrip line main body on which the high frequency filter substrate of FIG. 1 is mounted.

In FIG. 1, the high frequency filter substrate 100 of the present invention is a substrate different from the parent substrate 201 of the microstrip line main body 200 of FIG. 2, and the high frequency strip lines 102 (1) ... 102 (5) is formed and constitutes a bandpass filter (BPF). Thus, in the present invention, characteristically, the high-frequency filter substrate 100 is formed or configured so as to be separated from the parent substrate 201 in advance.

By mounting this child board 101 on the surface of the parent board 201 as shown in FIG. 2, the band pass filter (BPF) in the microstrip line main body 200 of FIG. 2 is made to function.

Of the high frequency strip lines on the surface of the child board 101, the strip lines 102 (2) to 102 (4) form a plane circuit pattern to form a high frequency filter circuit. Further, among the high frequency strip lines, the input section 102 (1) and the output section 102 (5) are arranged so as to be respectively connectable to the high frequency strip line 202 on the surface of the parent substrate 201 in FIG.

The high frequency strip line 102
(1) to 102 (5) are shielded (shielded) by at least the ground conductor 105 provided on the entire rear surface of the child board 101, and more preferably together with the ground conductor 105. The point that it has is also characteristic.
That is, the ground conductors provided on both sides of the surface of the child board 101.
The ground conductors 105 provided on the entire surfaces of the rear surfaces of the 103, 103 and the child board 101 are high-frequency strip lines 102 (1) -102.
(5) is shielded from the side surface and the back surface side of the daughter board except for the strip line front surface portion (width a). However, the strip line surface portion is also substantially shielded by the ground conductor by mounting the child substrate 101 on the surface of the parent substrate 201, which will be described later. Further, the ground conductors 103 1, 103 have a large number of through holes 104 1, 104 arranged at intervals.

On the other hand, in FIG. 2, the microstripline main body 200 of the present invention is constructed by forming high-frequency striplines 202 (1) to 202 (2) on the surface of the parent substrate 201. And with the high frequency strip line 202 (1)
Between 202 (2), the high frequency filter substrate 100 of the present invention.
As a part for mounting the high frequency filter substrate 10
An interval corresponding to a length of 0 is provided. Further, a connection portion (output portion) 202a and a connection portion (input portion) 202b are provided at the end of the high frequency strip line 202 (1) and the end of the high frequency strip line 202 (2), respectively.
Is provided. The ground conductors 203 and 203 are provided on both sides of the high frequency strip lines 202 (1) and 202 (2) on the front surface of the parent board 201, and the ground conductors are provided on the back surface of the parent board 201.
205 are provided respectively.

When mounting such a high-frequency filter substrate 100 on the microstrip line main body 200, as shown in FIG.
As shown in FIG. 3, the high frequency filter substrate 100 of FIG. 1 is mounted upside down with the back surface side up (the ground conductor 105 side up). As a mounting method, a known method for mounting a circuit such as soldering or an adhesive is appropriately selected.

At this time, as shown in FIG. 2, the input section 102 (1) and the output section 102 (5) on the high frequency filter substrate 100 side are
The connection part (output part) 202a and the connection part of the high-frequency stripline 202 (1) on the microstripline main body 200 side
(Input unit) Each is connected to 202b. With this connection, the high frequency filter substrate 100 is
It functions as a bandpass filter (BPF) at 200.

As described above, in the present invention, the input section 102 (1) and the output section 102 (5) on the high frequency filter substrate 100 side are the same as the parent substrate 201 on the microstrip line main body 200 side.
It is directly exposed on the surface. Therefore, an unnecessary connection portion for signal extraction, such as the filter circuit having the triplate structure, is unnecessary. Therefore, the radiation loss does not occur at such a connecting portion, and the distortion of the frequency characteristic does not occur.

Further, since the input section 102 (1) and the output section 102 (5) are directly exposed on the surface of the parent substrate 201, a surface mount type active element is provided around the high frequency filter substrate or the high frequency filter circuit. There is also a secondary effect that microwave and forward millimeter-wave circuits can be easily implemented.

Further, in the high frequency filter substrate of the present invention, if the precision of at least only the planar circuit pattern portion as the filter circuit is partially increased including the substrate,
The frequency accuracy can be increased. Therefore, unlike the filter circuit of the triplate structure, it is not necessary to accurately manufacture the substrate of the microstrip line body itself, and there is also an advantage that the manufacture including the microstrip line body is relatively easy.

On the other hand, when mounting the high frequency filter substrate 100 on the microstrip line main body 200 described above,
The ground conductors 103, 103 on the high frequency filter substrate 100 side,
Reference numeral 105 denotes the ground conductors 203, 203 provided in advance on the surface of the parent substrate 201 on the microstrip line main body 200 side.
Also, it functions as a ground conductor by being connected to the ground conductor 205 provided in advance on the back surface of the parent board 201.

The through-holes 104, 104 of the ground conductors 103, 103 are also connected by connecting the ground conductors to each other.
Similarly, the ground conductors 203 1, 203 and 205 on the parent board 201 side are also connected and communicated with through holes 204 1, 204 provided in advance to function as through hole conductors. These through holes are formed by attaching a conductive metal material such as copper to the inner wall surface of a plurality of vertically extending cylindrical through holes on each dielectric substrate by plating or the like. .

Therefore, in order for these ground conductors on the high-frequency filter substrate 100 side to exhibit the shield function, it is necessary to connect them to the ground conductors and through holes which are previously provided on the microstrip line main body 200 side. The ground conductor 205 provided on the back surface of the parent substrate 201 may be partially provided only in a region corresponding to the mounting portion of the high frequency filter substrate 100, and the microstrip line main body 20
In order to obtain a shield effect of 0, the back surface of the main substrate 201 (the microstrip line main body 20
It is preferable to provide the entire surface or a part of the back surface). However, in any case, the ground conductor 205 provided on the back surface of the parent substrate 201 needs to have at least an area corresponding to the high frequency filter substrate 100 in order to exert the shield function.

As described above, by mounting the high frequency filter substrate 100 on the microstrip line main body 200, the high frequency strip line of the high frequency filter substrate 100 can be obtained.
102 (1) to 102 (5) are the ground conductors 103, 103, 105 and the main board.
It is shielded (enclosed) by the ground conductors 203 1, 203, and 205 on the 201 side to form a shield around and around the filter circuit of the high-frequency filter substrate 100. As a result, it is possible to prevent radiation loss that occurs in the conventional high-frequency filter circuit and signal reception from the outside.

Next, more specific embodiments of the respective constituents of the high frequency filter substrate 100 and the microstrip line body 200 of the present invention will be described.

The parent board 201 of FIG. 2 and the child board 101 of FIG. 1 are made of a known dielectric material in which resin, a mixture of resin and ceramics, or ceramics alone is appropriately selected. The width and thickness of these substrates and dielectrics are determined, for example, by the relationship between the frequency of signals required for the wireless LAN system and the loss of high frequencies. For example, in a standard indoor WLAN system such as an office, 0.1
Thickness of ~ 2.0mm and width of 10 ~ 50mm.

Here, it is preferable to increase the dielectric constant of the dielectric in order to reduce the radiation loss in the high frequency loss from the microstrip line. This dielectric constant is determined by the dielectric constant of the dielectric material itself that constitutes the dielectric and the thickness of the dielectric.

If the dielectric material of the child substrate is selected so that the dielectric constant becomes high, the wavelength on the child substrate can be shortened, so that the high frequency filter substrate itself can be miniaturized. For example, when an inexpensive dielectric material (substrate) having a dielectric constant of about 4 is selected for the parent substrate and a ceramic powder-containing dielectric material (substrate) having a dielectric constant of about 10 is selected for the child substrate, the high frequency filter substrate itself Can be significantly miniaturized.

On the other hand, when the frequency handled by the high-frequency filter substrate is high and the wavelength is extremely short, conversely, if the dielectric material and thickness of the sub-substrate are selected so that the dielectric constant becomes low, the wavelength on the sub-substrate will be Therefore, the processing accuracy of the high frequency filter substrate itself can be relaxed.

Furthermore, since the dielectric loss from the microstrip line is determined by the dielectric material itself constituting the dielectric, it is preferable to select a low dielectric loss material from known resin dielectric materials and ceramics dielectric materials.

The material and thickness of the parent board 201 and the child board 101 may be the same, and the material and thickness of the board may be changed depending on the difference in function between the microstrip line main body 200 and the high frequency filter board 100. May be different.

Further, the high frequency strip lines 102 (1) to 102 (5) of the high frequency filter substrate 100 and the high frequency strip lines 202 (1) to 20 of the microstrip line main body 200.
2 (2) or ground conductor on the high-frequency filter board 100 side
Conductive materials such as 103, 103 (front side of substrate), 105 (back side of substrate) and ground conductors 204, 204 (front side of substrate), 205 (back side of substrate) of the microstrip line main body 200 side are
Conductive metals such as copper, aluminum, tin, gold, nickel and solder, and other conductive materials are appropriately selected. Then, a conductor used by using these conductive materials alone or in combination or in combination can be appropriately used.
For forming the high-frequency strip line, the ground conductor, and the like on the surface of the substrate, known methods such as laminating of conductive material foils, sticking or plating, a printing method, and a lithographic method can be applied.

Next, a mode of the high frequency filter circuit of the high frequency filter substrate 100 will be described. The high frequency filter circuit of the high frequency filter substrate 100 constitutes a distributed constant circuit using a microstrip line as described above. As a concrete example of this, in FIG. 1, the filter circuit has three high-frequency strip lines 102 (2) to 102 (4) of a minute width made of a conductor such as the metal, which are spaced apart from each other by a predetermined distance. It has a structure in which they are spaced apart and arranged in parallel with each other.

The high frequency strip lines 102 (2) to 102
The individual length and width of (4) (shape and size of the high-frequency strip line) determine the pass frequency characteristic and bandwidth of the high-frequency filter substrate 100 of the present invention. The present invention high-frequency filter substrate 10
0 is, so to speak, separated and independent from the high frequency strip line 202 of the main substrate, so that the high frequency strip line 202 of the main substrate can be used for the filter function such as the frequency characteristic.
Another characteristic is that it is not easily affected by the side.

That is, the adjacent high frequency strip lines 10
2 (2) to 102 (4) are arranged so as to be offset in each longitudinal direction so that portions having a length of about ¼ of the high frequency wavelength λ to be passed overlap each other. The high frequency strip lines 102 (2) to 102 (4) have a length of about ½ of the high frequency wavelength λ desired to pass and are designed to resonate with a signal of the wavelength λ.

Such a high frequency filter circuit has the above-mentioned BP
As described in the function of F, for the high frequency radio wave RF1 (wavelength λ0) input from the high frequency strip line 202 (1) on the microstrip line body 200 side, only the high frequency signal RF2 of the desired wavelength λ is supplied to the high frequency strip line. It has the function of outputting to 202 (2).

More specifically, the high frequency radio wave RF1 (wavelength λ0) propagating through the high frequency strip line 202 (1) on the side of the microstrip line main body 200 is surface-contacted via the connection portion (output portion) 202a. The signal is input to the high frequency strip line 102 (2) through the input unit 102 (1) on the high frequency filter substrate 100 side. High frequency radio wave RF1 is high frequency strip line
While sequentially passing through 102 (2) to 102 (4), the component of the wavelength λ of the wavelength λ0 to be passed is hardly attenuated. On the other hand, wavelength components other than the resonance frequency (wavelength λ) are attenuated and removed. As a result, the high frequency strip line 20 that is in surface contact with the output section 102 (5) on the high frequency filter substrate 100 side.
Only the high-frequency signal RF2 having a desired wavelength λ is output to the high-frequency strip line 202 (2) through the 2 (2) connection section (input section) 202b.

The function (function) and structure of the high frequency filter circuit of FIGS. 1 and 2 will be further described with reference to the explanatory diagram of the relationship between the pass loss of the high frequency filter substrate and the wavelength of FIG. Microstrip line main unit 200 high frequency strip line
When the signal a input from 202 (1) sequentially passes through the three high frequency strip lines 102 (2) to 102 (4), it is attenuated with a pass loss characteristic b 1 according to its wavelength.

Further, in order to make the pass band width c narrower, the number of the high-frequency strip lines 102 (2) to 102 (4) is changed from the current three, assuming that the high frequency strip lines 102 (2) to 102 (4) are arranged in the same manner.
Increase the number to 4 or more, for example, to arrange 5 or 7. On the contrary, in order to make the pass bandwidth wider than b, the high frequency strip lines 102 (2) to 102
The arrangement itself of (4) is the same, but the number is reduced to one.

However, the high frequency strip line 102 (2)
As the number of ~ 102 (4) is increased to narrow the pass band width of the high frequency filter circuit of FIGS. 1 and 2, the loss amount of the high frequency radio wave becomes large as shown in d of FIG.

Further, as described above, since the frequency characteristics of the filter are determined by the individual length and width of the high frequency strip line 102, it is required that the high frequency strip line 102 has a high processing accuracy for the length and width. Therefore, the narrower the pass bandwidth, the higher the processing cost.

Therefore, the high frequency strip line 10
The design number of 2 (2) to 102 (4) is determined from various points such as the relationship between the desired wavelength of the high frequency signal and the allowable loss of the high frequency radio wave, and the allowable manufacturing cost.

The high-frequency filter circuit in the high-frequency filter substrate of the present invention is not limited to the embodiment shown in FIGS. 1 and 2 depending on the wavelength to be removed or the wavelength to be taken out, but a distributed constant circuit using a microstrip line. The planar circuit pattern itself can be appropriately or freely selected within the range of the configuration.

For example, another embodiment of the high frequency filter circuit in the high frequency filter substrate of the present invention is illustrated in FIGS. The filter circuit 102 (6) in FIG. 4 has a fan shape in plan view, and is connected to the high-frequency strip line 102b at the root of the fan shape. Further, the filter circuit 102 (7) in FIG. 5 has a rectangular shape (rectangular shape) in the same plane as the high frequency strip line 102b, and is connected to the high frequency strip line 102b at one end portion in the longitudinal direction. There is. These filter circuits 102 (6) and 102 (7) in Figures 4 and 5
Contrary to the case of FIG. 3, is used for removing a signal of a specific wavelength.

As described above, the high-frequency filter circuit in the high-frequency filter substrate of the present invention has an advantage that the high-frequency signal can be freely selected according to the wavelength to be removed or the wavelength to be taken out at an appropriate portion of the microstrip line body. is there.

In addition, these plane circuit patterns are different,
Alternatively, there is an advantage in that it is possible to freely select and combine high frequency filter circuits having the same planar circuit pattern, mount them at desired locations on the microstrip line body, and further freely select high frequency signals. For example, when making devices with different frequencies (microstrip line body), the parent board is common and only the child board of the high frequency filter circuit is replaced, so that the frequency of the filter can be changed to accommodate different frequencies. The device can be provided at low cost.

Therefore, the present invention can realize a high-frequency filter substrate and a microstrip line which are rich in applicability, adaptability and adaptability due to these effects. In the above embodiment, the band pass filter (BPF) is mainly described among the filters designed as the distributed constant circuit. However, the configuration of the present invention can be appropriately applied to other high frequency filters such as a low pass filter (LPF), a high pass filter (HPF), and a band rejection filter.

[0064]

As described above, according to the present invention,
A high-frequency filter substrate that has a reliable shielding effect and can be easily attached to a microstrip line and has a wide range of applicability, adaptability, and adaptability. It is possible to provide a microstrip line that is highly versatile.

[Brief description of drawings]

FIG. 1 is a perspective view showing one embodiment of a high-frequency filter substrate of the present invention.

FIG. 2 is a perspective view showing an embodiment of a microstrip line main body of the present invention on which the high frequency filter substrate of FIG. 1 is mounted.

FIG. 3 is an explanatory view showing the operation of the high frequency filter substrate of the present invention.

FIG. 4 is a plan view showing another embodiment of the high-frequency filter circuit according to the present invention.

FIG. 5 is a plan view showing another embodiment of the high frequency filter circuit according to the present invention.

FIG. 6 is a plan view showing the configuration of a conventional bandpass filter.

FIG. 7 is a perspective view showing a conventional filter shield structure having a triplate structure.

[Explanation of symbols]

100: High frequency filter substrate, 101: Substrate, 102 (1) to 10
2 (5): High frequency strip line, 102 (1): Input section, 102
(5): output part, 103, 103, 105: ground conductor, 104: through hole 200: microstrip line body, 201: parent board,
202 (1) to 202 (2): High frequency strip line, 203: Ground conductor, 204: Through hole, 205: Ground conductor,

Claims (2)

[Claims] 1. A microstrip line on which an attachable high-frequency filter substrate is mounted, the high-frequency filter substrate being a substrate made of a dielectric material, and a high-frequency strip line made of a conductor formed on the surface of the substrate. The microstrip line is composed of an input part, an output part, a high-frequency filter circuit formed on the high-frequency strip line, and a ground conductor formed on at least the back surface of the substrate, while the microstrip line includes a substrate made of a dielectric material. A high frequency strip line made of a conductor formed on the front surface of the substrate, and a ground conductor formed on at least a part of the back surface of the substrate, and has a mounting portion on which the high frequency filter substrate is mounted. , The surface side of the high-frequency filter substrate is mounted on the surface side of the mounting portion of the microstrip line. In addition, the input section and the output section on the high-frequency filter substrate side are respectively connected to the high-frequency strip lines on the microstrip line side, and the ground conductor on the high-frequency filter substrate side is connected to the ground conductor on the mounting portion side. A microstrip line characterized by being connected. 2. A high-frequency filter substrate which can be mounted on the microstrip line according to claim 1, wherein the substrate is made of a dielectric material, a high-frequency strip line is made of a conductor formed on the surface of the substrate, and the high-frequency strip line is made. An input section and an output section and a high-frequency filter circuit formed in
A high-frequency filter substrate, comprising: a ground conductor formed on at least a part of the back surface of the substrate.