JP2011055328A - Crossing structure of transmission line - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crossing structure of transmission lines in which the transmission lines can be sufficiently isolated, the structure is simplified and costs are reduced. <P>SOLUTION: In a crossing structure of the transmission lines for crossing microstrip lines 1, 2, each of the microstrip lines 1, 2 is a transmission line of a planar structure type, and a point A on the microstrip line 1 separated from the center of a crossing part of the microstrip lines 1, 2 only for a predetermined first distance s1 and a point B on the microstrip line 2 separated from the center only for a predetermined second distance s2 are connected by a lead wire 4 having a length (d). When a center frequency of a frequency band to be used is defined as fc, the distances s1 and s2 are made minute relative to a wavelength at the center frequency fc, parasitic capacitance between the microstrip lines 1, 2 at the crossing part is defined as C and the equivalent inductance of the lead wire 4 is defined as L, the length (d) is adjusted to such a length that the center frequency fc becomes almost 1/(2π(LC)<SP>0.5</SP>), and determined. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a crossing structure of transmission lines, and more particularly to a crossing structure of transmission lines used for crossing planar structure type high-frequency transmission lines without coupling.

  When crossing a planar structure type high-frequency transmission line such as a microstrip line, there is a problem that isolation between transmission lines cannot be obtained due to parasitic capacitance generated between the transmission lines.

  As a conventional example for solving this problem, there has been proposed a method of reducing the coupling between lines by partially narrowing the line width of the part where the transmission lines intersect (see, for example, Patent Document 1).

  As another conventional example, there is a method of reducing coupling between transmission lines by installing a ground layer between the transmission lines at the intersection of the transmission lines (see, for example, Patent Documents 2 and 3).

Japanese Patent No. 3455995 Japanese Patent No. 3263919 JP 2002-368507 A

  However, in the crossing structure of the transmission lines in Patent Document 1, when the transmission lines are close to each other at the crossing portion, the isolation between the transmission lines cannot be sufficiently obtained even if the line width is narrowed. There was a point.

  Further, in the crossing structure of the transmission lines in Patent Documents 2 and 3, since an extra ground layer is required between the transmission lines, the structure becomes complicated, and both the material cost and the manufacturing cost increase. It was.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a transmission line crossing structure with sufficient isolation, simple structure, and low cost. .

In the crossing structure of the transmission line that crosses the first transmission line and the second transmission line, the first transmission line and the second transmission line are planar structure type transmission lines, A point A on the first transmission line that is a predetermined first distance s1 away from the center of the intersection between the first transmission line and the second transmission line, and a predetermined second distance s2 from the center. The point B on the second transmission line separated by a distance is connected by a conducting wire having a length d, the center frequency of the used frequency band is fc, and the distances s1 and s2 are compared with the wavelength at the center frequency fc. The parasitic capacitance between the first transmission line and the second transmission line at the intersection is C, the equivalent inductance of the conductor is L, and the length d is the center frequency fc. Adjusted to a length of about 1 / (2π (LC) ^0.5 ) It is a crossing structure of transmission lines characterized by being arranged.

In the crossing structure of the transmission line that crosses the first transmission line and the second transmission line, the first transmission line and the second transmission line are planar structure type transmission lines, A point A on the first transmission line that is a predetermined first distance s1 away from the center of the intersection between the first transmission line and the second transmission line, and a predetermined second distance s2 from the center. The point B on the second transmission line separated by a distance is connected by a conducting wire having a length d, the center frequency of the used frequency band is fc, and the distances s1 and s2 are compared with the wavelength at the center frequency fc. The parasitic capacitance between the first transmission line and the second transmission line at the intersection is C, the equivalent inductance of the conductor is L, and the length d is the center frequency fc. Adjusted to a length of about 1 / (2π (LC) ^0.5 ) Since the crossing structure of the transmission lines is characterized by being arranged, the transmission lines can be sufficiently isolated, the structure is simple, and the cost can be reduced.

It is a block diagram which shows the structure of the crossing structure of the transmission line which concerns on Embodiment 1 of this invention. It is explanatory drawing which showed the operation | movement mechanism of the crossing structure of the transmission line which concerns on Embodiment 1 of this invention. It is a block diagram which shows the structure of the crossing structure of the transmission line which concerns on Embodiment 2 of this invention. It is a block diagram which shows the structure of the crossing structure of the transmission line which concerns on Embodiment 3 of this invention. It is a block diagram which shows the structure of the crossing structure of the transmission line which concerns on Embodiment 4 of this invention. It is a block diagram which shows the structure of the crossing structure of the transmission line which concerns on Embodiment 5 of this invention.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a crossing structure of transmission lines according to Embodiment 1 of the present invention. FIG. 1A is a top view, and FIG. 1B is a cross-sectional view taken along the line DD in FIG. FIG. 2 is an explanatory diagram showing an operation mechanism of the transmission line intersection structure according to Embodiment 1 of the present invention.

  A crossing structure of transmission lines according to Embodiment 1 of the present invention will be described with reference to FIG. In FIG. 1, a substantially rectangular flat dielectric 11 serving as a substrate is provided. As shown in FIG. 1B, a planar ground conductor is provided below the dielectric 11 (on the −z direction side). 21 is provided. A flat dielectric 12 is disposed between the dielectric 11 and the ground conductor 21.

  Further, both the microstrip line 1 and the microstrip line 2 are formed substantially in a straight line, and they are arranged in directions crossing each other. As shown in FIG. 1B, the microstrip line 1 is formed on the surface of the dielectric 11 at a portion other than the intersection with the microstrip line 2, and the back surface of the dielectric 11 at the intersection. Is formed. A portion formed on the surface of the dielectric 11 of the microstrip line 1 is denoted by 1a, and a portion formed on the back surface of the dielectric 11 is denoted by 1b. On the other hand, the microstrip line 2 is formed on the surface of the dielectric 11 over the entire length.

  The microstrip line 1a formed on the surface of the dielectric 11 and the microstrip line 1b formed on the back surface of the dielectric 11 are through-holes provided through the dielectric 11 at both ends of the microstrip line 1b. They are connected via holes 3. That is, the microstrip line 1a and the microstrip line 1b have a portion that overlaps with the dielectric 11 in the horizontal direction (x direction) at the connection portion. A flat dielectric 12 is provided so as to contact the back surface of the dielectric 11 and the microstrip line 1b. Further, a point A on the microstrip line 1 that is separated from the center of the intersection of the microstrip line 1 and the microstrip line 2 by a predetermined distance s1, and a microstrip that is separated from the center of the intersection by a predetermined distance s2. A point B on the line 2 is connected by a conducting wire 4. At this time, if the center frequency of the used frequency band is fc, the width of the microstrip line 1a is w1, and the width of the microstrip line 2 is w2, the distance s1 is w2 / 2 by about 1/100 of the wavelength at the frequency fc. It is appropriately determined so as to be larger and smaller. The distance s2 is appropriately determined to be a minute value larger than w1 / 2 by about 1/100 of the wavelength at the frequency fc. In addition, the conducting wire 4 is formed on the surface of the dielectric 11 so as to have a U shape, for example.

  In FIG. 1, there are a port 101 and a port 102 at both ends of the microstrip line 1, and a port 103 and a port 104 at both ends of the microstrip line 2.

  Here, a case where a high frequency is transmitted to both the microstrip line 1 and the microstrip line 2 or a case where a high frequency is transmitted to either the microstrip line 1 or the microstrip line 2 is considered. In the latter case, for example, it may be possible to transmit direct current to a microstrip line that does not transmit high frequency. The center frequency of the used frequency band at this time is fc.

  Next, the operation will be described. FIG. 2 shows the operation mechanism. At the intersection between the microstrip line 1b and the microstrip line 2, a parasitic capacitance C (31 in FIG. 2) is generated between these lines. Further, the length d of the conductive wire 4 installed between the microstrip line 1a and the microstrip line 2 acts as an inductance L (32 in FIG. 2). Therefore, it can be considered that a parallel resonant circuit is installed between the microstrip line 1 and the microstrip line 2.

The resonance frequency _{f r} of the parallel resonant circuit is expressed as ^{1 / (2π (LC) 0.5} ). If R is a resistance connected in parallel to L and C, Q (quality factor of the resonant circuit) is expressed as 2πf _r CR. Since the magnitude of the impedance of the parallel resonant circuit at the resonant frequency f _r is maximum, if fc ≒ f _r, it is possible to reduce the coupling between the microstrip line 1 and the microstrip line 2 in fc vicinity .

Therefore, if the length d of the conducting wire 4 is determined by adjusting so that fc is about 1 / (2π (LC) ^0.5 ), sufficient isolation between the microstrip line 1 and the microstrip line 2 is ensured. can do.

  In the transmission line intersection structure according to the first embodiment shown in FIG. 1, the microstrip line 1 and the microstrip line 2 are described as being orthogonal to each other, but these are not necessarily orthogonal. You don't have to.

  In the crossing structure of the transmission lines according to the first embodiment, the microstrip line 1a, the microstrip line 2, and the conductor 4 are formed on the surface of the dielectric 11, and the microstrip line 1b is formed on the back surface of the dielectric 11. The operation principle is not limited to this case, but the microstrip line 1a, the microstrip line 2, and the conductive wire 4 are formed on the back surface of the dielectric 11, and the microstrip line 1b is formed on the surface of the dielectric 11. The same effect can be obtained.

Further, the conductive wire 4 need not be formed on the surface of the dielectric 11. Further, although the lead wire 4 has a U-shape in FIG. 1, the length d may be set so that fc is about 1 / (2π (LC) ^0.5 ), and the shape is arbitrary.

  The dielectric 11 may be a film substrate. Since the film substrate is thin, the characteristic impedances of the microstrip line 1a and the microstrip line 1b are substantially equal, and the amount of reflection at each port can be further reduced. Furthermore, the dielectric 11 does not need to be rectangular, and can be any shape such as a circle or a polygon. Further, the microstrip line 1 and the microstrip line 2 do not have to be in a straight line, and may be in a linear shape such as a curve.

As described above, in the present embodiment, the microstrip lines 1 and 2 are connected by the conductive wire 4 in the vicinity of the intersection of the microstrip lines, and the length d of the conductive wire 4 is set to the microstrip lines 1 and 2. When the parasitic capacitance between the microstrip lines 1 and 2 is C and the equivalent inductance of the conductor 4 is L, the center frequency fc of the used frequency band is about 1 / (2π (LC) ^0.5 ). By determining in this way, there is an effect that the microstrip lines 1 and 2 can be sufficiently isolated, and the structure is simple and a low-cost transmission line crossing structure can be obtained.

Embodiment 2. FIG.
The second embodiment shows an embodiment in which the microstrip line is a triplate line in the transmission line crossing structure according to the first embodiment. FIG. 3 is a diagram showing a crossing structure of transmission lines according to Embodiment 2 of the present invention. 3A is a top view seen from the line EE in FIG. 3B, and FIG. 3B is a cross-sectional view taken along the line DD in FIG.

  The crossing structure of the transmission line in FIG. 3 is the same as the crossing structure of the transmission line in FIG. 1 except that a planar ground conductor 22 is installed above the microstrip line 1 and the microstrip line 2 (on the + z direction side). The line 1 and the microstrip line 2 are triplate lines. A flat dielectric 13 is provided between the microstrip line 1 a and microstrip line 2 and the ground conductor 22.

  As described above, the difference in configuration between the present embodiment and the first embodiment is simply that the dielectric 13 and the ground conductor 22 are added in the present embodiment. Since it is the same as the first embodiment, the description thereof is omitted here.

As in the present embodiment, even if the microstrip line 1 and the microstrip line 2 are triplate lines, the operation principle is the same as that of the first embodiment, and the length of the conductive wire 4 is about 1/1 /. If the adjustment is made so that (2π (LC) ^0.5 ), the isolation between the lines can be sufficiently secured.

  As described above, in the present embodiment, the planar ground conductor 22 is installed above the microstrip line 1 and the microstrip line 2, and the microstrip line 1 and the microstrip line 2 are triplate lines. In the vicinity of the intersection of the triplate lines, by connecting the conductive wires 4 whose lengths are adjusted between the triplate lines, sufficient isolation can be obtained between the triplate lines, the configuration is simple, and the transmission line is low in cost. This has the effect that a crossing structure is obtained.

Embodiment 3 FIG.
In the third embodiment, in the crossing structure of the transmission lines according to the first embodiment, the conductive wire 4 is not provided, but instead a chip inductor is installed between the microstrip lines 1 and 2. Indicates. FIG. 4 is a diagram showing a crossing structure of transmission lines according to Embodiment 3 of the present invention. 4A is a top view, and FIG. 4B is a cross-sectional view taken along the line DD in FIG. 4A.

  The transmission line crossing structure of FIG. 4 is the same as the transmission line crossing structure of FIG. 1 except that the conductive wire 4 is removed and the microstrip is separated from the center of the crossing part of the microstrip line 1 and the microstrip line 2 by a predetermined distance s1. A point A on the line 1 and a point B on the microstrip line 2 separated from the center of the intersection by a predetermined distance s 2 are connected via a chip inductor 5.

  Since other configurations are the same as those of the first embodiment, description thereof is omitted here.

Even if the chip inductor 5 is used in place of the conductive wire 4, the operation principle is the same as that of the first embodiment, the inductance of the chip inductor 5 is L, and the center frequency fc of the used frequency band is about 1 / (2π If the value of L is adjusted so that (LC) ^0.5 ), the isolation between the microstrip lines 1 and 2 can be sufficiently secured.

  Further, by using the chip inductor 5, the cross structure of the transmission line can be further reduced in size. In order to connect the chip inductor 5 and the point A on the microstrip line 1, a conductive wire having a length of about 1/100 to 1/50 of the wavelength at the frequency fc is provided between the chip inductor 5 and the point A. It is also possible. Similarly, in order to connect the chip inductor 5 and the point B on the microstrip line 2, a lead wire having a length of about 1/100 to 1/50 of the wavelength at the frequency fc is connected between the chip inductor 5 and the point B. It is also possible to provide it.

  As described above, in the present embodiment, between the microstrip lines 1 and 2 by connecting the microstrip lines 1 and 2 via the chip inductor 5 in the vicinity of the intersection of the microstrip lines 1 and 2. Therefore, it is possible to obtain a transmission line crossing structure that is sufficiently isolated, small in size, simple in configuration, and low in cost.

Embodiment 4 FIG.
In the fourth embodiment, the transmission line crossing structure according to the first embodiment shows an embodiment in which the line width at the crossing portion is narrowed. 5 is a diagram showing a crossing structure of transmission lines according to Embodiment 4 of the present invention. 5A is a top view, and FIG. 5B is a cross-sectional view taken along the line DD in FIG. 5A.

  In the crossing structure of the transmission lines in FIG. 5, the line widths of the microstrip line 1a and the microstrip line 2 are made narrower at the crossing portions than at the crossing portions.

As described in the first embodiment, the Q of the parallel resonant circuit existing equivalently between the microstrip line 1 and the microstrip line 2 is expressed as 2πf _r CR. Therefore, as the parasitic capacitance C is reduced, Q is reduced and the bandwidth is increased. That is, by narrowing the line width of the microstrip line 1 and the microstrip line 2 at the intersection and reducing the parasitic capacitance C, the frequency band in which the line-to-line coupling can be reduced can be further widened.

  Since other configurations are the same as those in the first embodiment, description thereof is omitted here.

  As described above, in the present embodiment, a conductor whose length is adjusted is connected between the microstrip lines 1 and 2 near the intersection of the microstrip lines 1 and 2, and the microstrip lines 1 and 2 are connected. By narrowing the width of these lines at the intersection of the two, the effect that the isolation between the microstrip lines 1 and 2 can be sufficiently obtained over a wide band, the configuration is simple, and a low-cost transmission line intersection structure is obtained. Have

Embodiment 5 FIG.
In the fifth embodiment, an embodiment in which a tip open line is connected in parallel to a microstrip line in the crossing structure of transmission lines according to the fourth embodiment will be described. FIG. 6 is a diagram showing a crossing structure of transmission lines according to Embodiment 5 of the present invention. 6A is a top view, and FIG. 6B is a cross-sectional view taken along the line DD in FIG. 6A.

  In the crossing structure of the transmission lines in FIG. 6, the open end line 41 and the open end line 42 are connected in parallel with the microstrip line 1a in the crossing structure of the transmission line in FIG. The open end line 43 and the open end line 44 are connected in parallel to the microstrip line 2.

  The open end lines 41, 42, 43, 44 are formed on the surface of the dielectric 11. The open end lines 41, 42, 43, and 44 are installed at positions where the electrical length from the center of the intersection of the microstrip lines 1 and 2 is equal to or less than a half wavelength at the center frequency fc of the used frequency band. Further, the open-end lines 41, 42, 43, and 44 have an electrical length of ¼ wavelength or less at fc.

  In FIG. 6, two open-ended lines are connected to each of the microstrip lines 1 and 2, but this is not a limitation, and the number of open-ended lines is not limited to the fourth embodiment. Absent.

  Since other configurations are the same as those in the fourth embodiment, description thereof is omitted here.

  Thus, in this Embodiment, the amount of reflections in each port can be made smaller by installing the open-end lines 41, 42, 43, and 44. That is, the passage loss between the port 101 and the port 102 and the passage loss between the port 103 and the port 104 can be reduced.

  As described above, in the present embodiment, the conductor 4 whose length is adjusted is connected between the microstrip lines 1 and 2 near the intersection of the microstrip lines 1 and 2, The width of the microstrip lines 1 and 2 is narrowed at the intersection of the two, and a plurality of open end lines 41, 42, 43, and 44 are provided in parallel with the microstrip lines 1 and 2, thereby There is an effect that the isolation between 1 and 2 can be sufficiently obtained over a wide band, the loss is small, the configuration is simple, and a low cost transmission line crossing structure is obtained.

  In the first to fifth embodiments described above, the examples in which the dielectrics 11 and 12 and the microstrip lines 1 and 2 are stacked in layers on the planar ground conductor 21 have been described. However, the present invention is not limited thereto. The ground conductor 21 may be curved, such as a cylinder, and the dielectrics 11 and 12 and the microstrip lines 1 and 2 may be installed in layers on the ground conductor 21, and even in that case, generally the same effect can be obtained. it can.

  1, 1a, 1b, 2 Microstrip line, 3 Through hole, 4 Conductor, 5 Chip inductor, 41, 42, 43, 44 Open-ended line, 11, 12, 13 Dielectric, 21, 22 Ground conductor, 101, 102 , 103, 104 ports.

Claims (7)

In the crossing structure of the transmission line that crosses the first transmission line and the second transmission line,
The first transmission line and the second transmission line are planar transmission lines,
A point A on the first transmission line that is a predetermined first distance s1 away from the center of the intersection of the first transmission line and the second transmission line, and a predetermined second distance from the center. The point B on the second transmission line separated by s2 is connected by a lead wire of length d,
The center frequency of the used frequency band is fc,
The distances s1 and s2 are minute compared to the wavelength at the center frequency fc,
A parasitic capacitance between the first transmission line and the second transmission line at the intersection is C,
Let L be the equivalent inductance of the conducting wire.
The transmission line intersection structure, wherein the length d is adjusted to a length at which the center frequency fc is about 1 / (2π (LC) ^0.5 ). A planar first dielectric;
A planar ground conductor disposed opposite the first dielectric;
A plate-like second dielectric provided between the first dielectric and the ground conductor;
A first microstrip line formed on a surface of the first dielectric;
Second and third microstrip lines disposed in a direction intersecting the first microstrip line;
A conducting wire having a length d provided on the surface of the first dielectric,
The second microstrip line is formed in a portion other than the intersection with the first microstrip line, and is formed on the surface of the first dielectric,
The third microstrip line is formed at the intersection, and is formed on the back surface of the first dielectric.
The second microstrip line and the third microstrip line are connected by a through hole provided through the first dielectric,
The point A on the first microstrip line that is separated from the center of the intersection by a predetermined first distance s1, and the second microstrip that is separated from the center of the intersection by a predetermined second distance s2. Point B on the track is connected by the conducting wire,
The center frequency of the used frequency band is fc,
The distances s1 and s2 are minute compared to the wavelength at the center frequency fc,
A parasitic capacitance between the first microstrip line and the third microstrip line at the intersection is C,
Let L be the equivalent inductance of the conducting wire.
The transmission line intersection structure, wherein the length d is adjusted to a length at which the center frequency fc is about 1 / (2π (LC) ^0.5 ). A plate-shaped third dielectric is installed on the opposite side of the first microstrip line and the second microstrip line from the first dielectric,
The transmission line crossing structure according to claim 2, wherein a planar second ground conductor is disposed on the opposite side of the third dielectric to the first microstrip line and the second microstrip line. A planar first dielectric;
A planar ground conductor disposed opposite the first dielectric;
A plate-like second dielectric provided between the first dielectric and the ground conductor;
A first microstrip line formed on a surface of the first dielectric;
Second and third microstrip lines disposed in a direction intersecting the first microstrip line;
A chip inductor provided on the surface of the first dielectric,
The second microstrip line is formed in a portion other than the intersection with the first microstrip line, and is formed on the surface of the first dielectric,
The third microstrip line is formed at the intersection, and is formed on the back surface of the first dielectric.
The second microstrip line and the third microstrip line are connected by a through hole provided through the first dielectric,
The point A on the first microstrip line that is separated from the center of the intersection by a predetermined first distance s1, and the second microstrip that is separated from the center of the intersection by a predetermined second distance s2. The point B on the line is connected by the chip inductor,
The center frequency of the used frequency band is fc,
The distances s1 and s2 are minute compared to the wavelength at the center frequency fc,
A parasitic capacitance between the first microstrip line and the third microstrip line at the intersection is C,
Let L be the inductance of the chip inductor.
The crossing structure of a transmission line, wherein the inductance L is adjusted to a value at which the center frequency fc is about 1 / (2π (LC) ^0.5 ). The width of the first microstrip line at the intersection is narrower than the portion other than the intersection,
5. The transmission line crossing structure according to claim 2, wherein a width of the third microstrip line at the crossing portion is narrower than a width of the second microstrip line. 6. . A plurality of open-ended lines are installed on the surface of the first dielectric,
The open end of the leading end is connected to the first microstrip line or the second microstrip line at an unopened end.
The electrical length between the connection portion and the center of the intersection is not more than a half wavelength at the center frequency fc,
6. The transmission line intersection structure according to claim 2, wherein the electrical length of the open-ended line is ¼ wavelength or less at the center frequency fc. The ground conductor is curved,
The crossing of the transmission line according to any one of claims 2 to 6, wherein the second dielectric and the first dielectric are layered on the curved ground conductor. Construction.

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