JP3950794B2 - Transmission line structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transmission line structure, and more particularly to a transmission line structure that can provide a desired characteristic impedance.
[0002]
[Prior art]
In the high-frequency planar circuit, impedance matching is performed so that the characteristic impedance becomes a constant value. In a microstrip circuit in which signal wiring is formed on the front surface side of the dielectric substrate and ground wiring is formed on the back surface side, the line width and the thickness of the dielectric substrate are adjusted so that, for example, the characteristic impedance is 50Ω. The material of the transmission line is not limited to a good electrical conductor such as Cu, Ag, Au, or Al, but an oxide high temperature superconductor is also used. When using an oxide high temperature superconductor layer for a transmission line, it is necessary to cool the transmission line. When the transmission line structure is cooled, the characteristic impedance also changes due to temperature changes. When the characteristic impedance deviates from a desired value, the transmission characteristic is deteriorated. In order to obtain desired characteristics, it is necessary to re-create the transmission line structure.
[0003]
Hereinafter, an example of a conventional microstrip transmission line structure will be described.
The structure shown in FIG. 5A is the most well-known structure in a microstrip circuit using a good electrical conductor. A signal wiring 105 is formed on the surface of the dielectric substrate 100, and a ground (ground) layer 106 is formed on the back surface.
[0004]
FIG. 5B shows a shape example of the signal wiring. In the figure, a signal wiring 105 bent in a zigzag shape is formed on the surface of a dielectric substrate 100 to constitute a delay circuit. The ground layer 106 is formed on the entire back surface.
[0005]
When a high-temperature oxide superconductor layer is used as the material for the transmission line instead of the good electrical conductor, it is possible to form a high-performance high-frequency circuit with lower loss than the good electrical conductor. In the structure of FIG. 5A, the signal wiring 105 and the ground layer 106 can be formed of an oxide high-temperature superconductor layer. However, forming an oxide superconductor layer on both surfaces of a dielectric substrate is extremely difficult to manufacture as compared to forming an oxide superconductor layer on one surface.
[0006]
5C to 5E show configuration examples suitable for manufacturing a microstrip circuit using an oxide superconductor layer. As shown in FIG. 5C, the signal wiring 105 of the oxide superconductor layer is formed on the surface of the first dielectric substrate 101.
[0007]
As shown in FIG. 5D, a ground layer 106 of an oxide superconductor layer is formed on the entire surface of another second dielectric substrate 102.
As shown in FIG. 5 (E), and the rear surface of the first dielectric substrate 101, bonding the back surface of the second dielectric substrate 102 and the single substrate 103. Then, a structure in which the signal wiring 105 is disposed on the front surface of the dielectric substrate 103 and the ground layer 106 is disposed on the back surface can be obtained.
[0008]
In the structure shown in FIG. 5E, when an air gap is generated between the first and second dielectric substrates 101 and 102, the characteristics of the dielectric substrate are disturbed, and the reproducibility of the frequency characteristics is impaired.
[0009]
In addition, the transmission line structure shown in FIG. 5E also needs to be cooled during use, and the characteristics of the transmission line change due to cooling. Even when the cooling temperature deviates from the design temperature, the characteristics of the transmission line deviate from the design values. When the characteristic deviates from the desired value, it is necessary to start from the design again in order to obtain the desired characteristic.
[0010]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-209722 [Patent Document 2]
Japanese Patent Laid-Open No. 2002-64312
[Problems to be solved by the invention]
An object of the present invention is to provide a transmission line structure capable of adjusting characteristic impedance.
[0012]
[Means for Solving the Problems]
According to one aspect of the present invention,
A first circuit board with signal wiring formed on the surface using a superconductor layer ;
A second circuit board provided with a ground layer formed using a superconductor layer on the surface, and arranged so that the back surface of the first circuit board and the ground layer face each other;
An adjustment mechanism capable of changing a characteristic impedance of a transmission line by adjusting a distance between the first circuit board and the second circuit board;
A package containing the first circuit board and the second circuit board, including at least two coaxial connectors, and a conductor formed of a normal metal;
There is provided a transmission line structure having a notch portion that is partially deleted so that the second circuit board does not collide with the coaxial connector even if the second circuit board moves relative to the package. The
[0013]
Since the characteristic impedance of the transmission line can be adjusted, it becomes easy to obtain a desired characteristic impedance. Even when the transmission line is cooled, the in-situ adjustment is possible, so that it is easy to obtain a desired characteristic impedance.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1A is a schematic cross-sectional view showing a configuration of a basic embodiment of the present invention. A signal wiring 5 such as a meander line is formed on the surface of the first dielectric substrate 1 to constitute a first substrate 11. A ground conductive layer 6 is formed on the entire surface of the second dielectric substrate 2 to form a second circuit substrate 12. The ground layer 6 of the second circuit board 12 is disposed so as to face the back surface of the dielectric substrate 1 of the first circuit board 11. An adjusting mechanism 13 that adjusts the distance between the first circuit board 11 and the second circuit board 12 is disposed on the back side of the second circuit board 12.
[0015]
According to such a configuration, the dielectric layer between the signal wiring 5 and the ground layer 6 is configured by the first dielectric substrate 1 and the air layer (or vacuum layer) 3. The effective relative dielectric constant of the dielectric layer between the signal wiring 5 and the ground layer 6 is determined by the dielectric substrate 1 and the air layer 3.
[0016]
When the thickness of the air layer 3 is reduced, the effective relative permittivity is increased, and when the thickness of the air layer 3 is increased, the effective relative permittivity is decreased. By moving the second circuit board 12 up and down by the adjusting mechanism 13, the thickness of the air layer 3 can be changed and the effective relative dielectric constant of the dielectric layer can be adjusted. The characteristic impedance can be adjusted by adjusting the effective relative dielectric constant.
[0017]
The wiring layers 5 and 6 may be formed of a good electrical conductor or an oxide superconductor. When the oxide superconductor layer is used, the thickness is preferably 0.5 μm or more in order to reduce loss and suppress damage that may occur during assembly of the package.
[0018]
The dielectric substrate 1 is formed of a dielectric having excellent high frequency characteristics. When the signal wiring 5 is an oxide superconductor layer, the substrate 1 can epitaxially grow an oxide superconductor layer thereon, and has a high dielectric constant and low loss magnesium oxide (MgO), lanthanum aluminum. Nate (LaAlO ₃ ), sapphire (Al ₂ O ₃ ) or the like is preferably used. When a hexagonal sapphire substrate is used, it is preferable to provide a buffer layer such as CeO ₂ between the substrate 1 and the superconductor layer.
[0019]
Since the substrate 2 is outside the electric field distribution region defined by the signal wiring 5 and the ground layer 6, it is not necessarily made of a dielectric. For example, magnesium oxide, lanthanum aluminate, sapphire, strontium oxide, cerium oxide, titanium oxide, silver, gold, nickel, nickel oxide, nickel alloy, etc. are selected from materials capable of epitaxially growing an oxide superconductor layer thereon. be able to.
[0020]
Any mechanism can be used as the adjusting mechanism 13 as long as the mechanism can drive the second substrate up and down. When the transmission line is cooled and used, it is desired to operate in a vacuum at a low temperature, and a simple configuration is preferable. A combination of a screw and a spring, a piezoelectric element, or the like can be used. When the transmission line is used at room temperature, a stepping motor or a mechanism using a gas or liquid medium pressure can also be used.
[0021]
1B to 1E are a perspective view and a cross-sectional view illustrating an example of the transmission line structure illustrated in FIG.
FIG. 1B shows a configuration example of the first circuit board 11 having signal wiring. For example, a meander line 5 of an oxide superconductor layer formed from Y—Ba—Cu—O (YBCO) is formed on the (100) plane of the MgO substrate 1. The oxide superconductor layer is a layer epitaxially grown on the MgO substrate.
[0022]
FIG. 1C shows a configuration example of the second circuit board 12. For example, the oxide superconductor layer 6 made of YBCO is formed on the surface of the (100) MgO substrate 2 to constitute a ground layer. In the configuration shown in the figure, a notch 9 is formed in a portion connected to the coaxial connector.
[0023]
FIG. 1D shows a state in which the first circuit board 11 and the second circuit board 12 are accommodated in the high-frequency package 18. The high frequency package 18 has two coaxial connectors 20 for high frequency input and high frequency output. A central conductor of the coaxial connector 20 is connected to the signal wiring 5.
[0024]
FIG. 1E shows an arrangement example of the coaxial connector 20 and the second circuit board 12. The coaxial connector 20 has a center conductor 21 and a ground conductor 22. The second circuit board 12 includes the dielectric substrate 2 and the ground conductor 6, but a notch 9 is formed at a portion facing the coaxial connector 20. The notch 9 prevents the ground conductor 22 of the coaxial connector 20 and the second circuit board 12 from colliding with each other.
[0025]
The width of the notch 9 can be selected to achieve a desired range of movement of the second circuit board 12, but is preferably narrower than the diameter of the outer conductor 22. If the diameter is larger than the diameter of the outer conductor 22, the path of the current flowing through the ground conductor 6 is circulated, and parasitic inductance is generated.
[0026]
2A to 2G show a method for manufacturing the first and second circuit boards 11 and 12 shown in FIG.
As shown in FIG. 2A, for example, (100) plane MgO substrates 1 and 2 having a diameter of 2 inches and a thickness of 0.5 mm are prepared. The thickness of the substrates 1 and 2 is preferably selected from 0.2 mm to 0.5 mm. The substrates 1 and 2 are mounted on a substrate holder, heated to about 700 ° C., and a Y-Ba—Cu—O (YBCO) oxide superconductor having a thickness of about 0.9 μm using a laser deposition method in an oxygen pressure of 240 mTorr. Body layers 5 and 6 are formed. After the film formation, oxygen 200 Torr is introduced, and the substrates 1 and 2 are cooled. Note that sputtering can be used instead of laser vapor deposition. In the case of sputtering, reactive sputtering is performed in an oxygen atmosphere using a YBCO target.
[0027]
As shown in FIG. 2B, in the signal wiring substrate, the oxide superconductor layer 5 formed on the MgO substrate 1 is patterned using photolithography and etching, and the meander line 5 Form. Etching is performed by wet etching or Ar ion milling. The wiring width is selected so as to obtain a desired characteristic impedance, for example, 50Ω. When the thickness of the substrate 1 is 0.5 mm, a characteristic impedance of 50Ω is obtained by a wiring having a line width of 0.5 mm. The substrate is processed into a desired size using a dicing saw. Since the (100) plane MgO substrate has a strong cleavage property, it can also be cleaved by scratching the end of the substrate with a diamond cutter.
[0028]
As shown in FIG. 2 (C), an electrode layer 7 of an electrically normal conductive good conductor is formed at the end of the meander line 5 of the signal wiring board 11. For example, an electrode layer 7 of Ag or Au is formed to facilitate later electrical connection.
[0029]
FIG. 2D shows the configuration of the ground layer substrate 12. The ground layer 6 does not need to be patterned, and after processing the substrate to a desired size, the good conductor layer 8 for electrical connection is formed on the ground layer 6 and the side surface of the substrate 2. Since the adhesion between the dielectric substrate and Ag or Au is poor, it is preferable to form a Pd (or Pt) / Cr (or Ti) stack as a lower layer and to form an upper layer of Ag or Au thereon.
[0030]
FIG. 2E shows an arrangement example of the electrical good conductor layer 8. The good conductor layer 8 is formed in the peripheral region of the substrate 2. However, the substrate is not formed in a region where the substrate is not cut later, but a mark for the substrate notch region is formed, and the substrate deleting step is facilitated. The good conductor layer 8 is preferably formed by sputtering or vapor deposition using a metal mask or a resist mask. A good conductor layer having a smooth surface can be obtained without deteriorating the oxide superconductor layer.
[0031]
As shown in FIG. 2F, two cuts 13 are formed in the second circuit board 12 using a dicing saw. Scratches 14 are made with a diamond cutter so as to correspond to the tip of the cut. The region surrounded by the cut portion 13 and the scratch 14 is cleaved and removed. Prior to this removal step, it is preferable to spin coat a resist layer on the surface. The resist layer serves to protect the oxide superconductor layer and the conductor layer. If the conductor layer 8 is present in the cleavage region, peeling may occur during cleavage. When the resist layer is applied, the resist is removed with acetone or the like after the cleavage step.
[0032]
FIG. 2G shows the planar shape of the obtained second circuit board 12. In the drawing, cuts 9 are formed on two opposing sides of the second circuit board 12, and a conductor layer 8 is formed so as to cover the oxide superconductor layer 6 on the periphery of the substrate excluding the cuts 9.
[0033]
3A to 3C show an example of two circuit boards housed in a high frequency package. 3A is a longitudinal sectional view, FIG. 3B is a bottom view, and FIG. 3C is a sectional view taken along line IIIC-IIIC in FIG. 3A. The high-frequency package 18 includes two coaxial connectors 20 and defines a closed space. A lifting mechanism including a screw 30 and a nut 31 is attached to one surface of the high-frequency package 18.
[0034]
The first circuit board 11 is arranged so that the signal layer 5 is connected to the center conductor 21 of the coaxial connector 20. The center conductor 21 and the signal layer 5 are connected by a bonding wire 23. Instead of the bonding wire 23, a connection conductor such as indium solder or gold tape can be used.
[0035]
A second circuit board 12 is disposed below the board 1. The board 2 of the second circuit board 12 is coupled to an adjustment mechanism having screws 30 and nuts 31. The conductor layer 8 at the periphery of the second circuit board 2 is disposed near the wall surface of the high-frequency package 18 and is in electrical contact with the wall surface of the high-frequency package 18 by a spring 24 such as phosphor bronze disposed thereon. . In place of the spring 24, indium solder or the like can be used.
[0036]
In use, the board 2 can be moved up and down by driving the screw 30. By driving the board 2 and adjusting the distance between the first circuit board 11 and the second circuit board 12, the effective relative dielectric constant between the signal wiring 5 and the ground layer 6 is changed, and the characteristic impedance is adjusted. can do.
[0037]
FIG. 6A shows an example of electrical connection using indium solder instead of the spring 24 of FIG. Indium solder 25 is formed on the side surface of the good conductor layer 8 of the second circuit board 12 to form an electrical connection with the high frequency package 18. The substrate 2 is pushed up by a coil spring 28 and pulled down by a screw. A metal invar layer 26 is formed on the contact surface between the coil 28 and the substrate 2. The metal invar layer 28 prevents damage due to contact between the coil spring 28 and the substrate 2.
[0038]
FIG. 6B shows another configuration example of the adjusting mechanism. A piezoelectric element 32 is disposed on the bottom surface of the high-frequency package 18, and the second circuit board 12 is supported on the piezoelectric element 32. By applying a voltage from the variable voltage source 33 to the piezoelectric element 32, the thickness of the piezoelectric element 32 can be changed, and the gap between the first circuit board and the second circuit board 12 can be adjusted.
[0039]
FIG. 4A shows a configuration example of a transmission line structure including a high frequency filter. The high frequency package 34 has two coaxial connectors 35 as in the above-described configuration. One coaxial connector 35 is a high frequency input terminal, and the other coaxial connector 35 is a high frequency output terminal. A first circuit board 11 in which a plurality of oxide superconductor layer patterns are electrically coupled is accommodated in the package. The oxide superconductor layer 5 on the first circuit board 11 constitutes a tunable three-stage bandpass filter. The second circuit board 12 is disposed below the first circuit board 11 and the height of the second circuit board 12 is adjusted by the screw 30 in the same manner as described above.
[0040]
FIG. 4B is a schematic perspective view showing a form in which the transmission line structure of FIG. 4A is actually used. A cold plate 41 is disposed in the vacuum container 30, and the high frequency package 34 shown in FIG. 4A is placed on the cold plate 41 in a vertically inverted state. The vacuum container 30 may be connected to a vacuum placement device, and may be sealed together with a getter in a state where it is evacuated. The cold plate 41 is connected to the refrigerator 42 and is cooled by the refrigerator 42. The refrigerator 42 is connected to the compressor 43 and receives supply of compressed refrigerant. Input / output terminals of the high-frequency package 34 are connected to input / output ports 37 and 38 via cables.
[0041]
While the vacuum container 40 is evacuated, the refrigerator 42 cools the cold plate 41 and the high-frequency package 34 thermally bonded thereto. After cooling to a desired temperature, the characteristic impedance is adjusted to an optimum value using the screw 30. A circuit in which a high-performance filter is connected between the input / output ports 37 and 38 is formed.
[0042]
Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. As oxide superconductors, in addition to YBCO, Bi (Pb) -Sr-Ca-Cu-O, Re-Ba-Cu-O (RE: La, Nd, Sm, Eu, Gd, Du, Er, Tm , Yb, Lu) or the like can also be used.
[0043]
The oxide superconductor layer can be formed by a coating method instead of laser vapor deposition or sputtering. In this case, a liquid phase oxide superconductor material layer is applied on the substrate and fired at a high temperature. The thickness of the oxide superconductor layer is preferably 0.5 μm or more as described above. Similar to the delay circuit and the filter, the resonator can be configured by a transmission line having a certain length.
[0044]
As the electrical conductor material, a good electrical conductor such as Cu, Ag, Au, Al, or a superconductor can be used. Other materials may be used as the oxide superconductor. It will be apparent to those skilled in the art that other various modifications, improvements, and combinations can be made.
[0045]
The features of the present invention will be described below.
(Appendix 1) (1) a first circuit board having signal wiring on the surface;
A second circuit board provided with a ground layer on the front surface, the rear surface of the first circuit board and the ground layer disposed so as to face each other;
An adjustment mechanism capable of changing a characteristic impedance of a transmission line by adjusting a distance between the first circuit board and the second circuit board;
A transmission line structure having:
[0046]
(Supplementary note 2) (2) The transmission line structure according to supplementary note 1, wherein the adjustment mechanism includes a mechanism for pushing up a back surface of the second circuit board.
(Supplementary note 3) (3) The transmission line structure according to Supplementary note 1 or 2, wherein the signal wiring and the ground layer are formed of any one of a superconductor, Au, Ag, and Cu.
[0047]
(Appendix 4) (4) The transmission line structure according to any one of appendices 1 to 3, wherein the adjustment mechanism includes a push screw or a piezoelectric element.
(Additional remark 5) (5) The said signal wiring and a ground layer are formed using a superconductor layer, Furthermore,
Housing the first circuit board and the second circuit board, including at least two coaxial connectors, and having a package in which a conductor is formed of a normal metal;
The transmission line structure according to appendix 1 or 2, wherein a part of the second circuit board is deleted so as not to collide with the coaxial connector even if the second circuit board moves relative to the package.
[0048]
(Additional remark 6) Furthermore, the vacuum vessel which accommodates the said package,
A cold stage thermally coupled to the package in the vacuum vessel and capable of cooling the package;
The transmission line structure according to appendix 5, wherein
[0049]
(Appendix 7) (6) The transmission line structure according to Appendix 5, wherein the signal wiring and the ground layer include a normal metal layer formed on at least a part of the surface of the superconductor layer.
(Supplementary Note 8) (7) said first and second circuit board MgO, LaAlO _3, transmission line structure according to Supplementary Note 5-7, wherein are formed using any of the underlying substrate of sapphire.
[0050]
(Supplementary note 9) (8) The transmission line structure according to supplementary note 8, wherein the base substrate has a thickness of 0.2 to 0.5 mm.
(Appendix 10) (9) The transmission line structure according to any one of appendices 5 to 9, wherein the superconductor layer has a thickness of 0.5 μm or more.
[0051]
(Additional remark 11) (10) The said adjustment mechanism has a spring which pushes up the said 2nd circuit board back surface, The said 2nd circuit board has the metal invar layer which receives the said spring in the back surface of Additional remarks 5-10 The transmission line structure of any one of Claims.
[0052]
(Supplementary note 12) The transmission line structure according to any one of supplementary notes 5 to 10, wherein the adjustment mechanism includes a piezoelectric element coupled to the back surface of the second circuit board.
(Supplementary Note 13) (a) A first circuit board having a signal wiring on the surface, a ground layer on the surface, and the back surface of the first circuit board and the ground layer are arranged to face each other. A transmission line structure comprising: a second circuit board; and an adjustment mechanism capable of changing a characteristic impedance of the transmission line by adjusting a distance between the first circuit board and the second circuit board. A preparation process;
(B) adjusting the characteristic impedance by adjusting the adjustment mechanism;
(C) applying a high frequency signal to the signal wiring;
A method of operating a transmission line structure including:
[0053]
(Supplementary note 14) The operation method of the transmission line structure according to supplementary note 13, further comprising a step of cooling the first and second circuit boards before the step (b).
(Supplementary Note 15) (a) forming a signal wiring on the surface of the first substrate and creating a first circuit board;
(B) forming a ground layer on the surface of the second substrate and creating a second circuit substrate;
(C) adjusting the distance between the first circuit board and the second circuit board to change the characteristic impedance of the transmission line; Accommodating the first circuit board and the second circuit board so that the back surface and the ground layer on the second substrate face each other;
A method for manufacturing a transmission line structure including:
[0054]
(Supplementary note 16) The supplementary note 15, wherein the package has a coaxial connector, and the step (b) includes a step of deleting a part of the second circuit board so as to prevent a collision with the coaxial connector. A method for manufacturing a transmission line structure.
[0055]
(Additional remark 17) The manufacturing method of the transmission line structure of Additional remark 15 or 16 in which the said process (a), (b) forms a superconducting layer, and forms the normal conductive good conductor layer for a connection on it.
[0056]
(Additional remark 18) The manufacturing method of the transmission line structure of Additional remark 17 with which the said normal conductive good conductor layer is formed by sputtering or vapor deposition using a mask.
[0057]
【The invention's effect】
As described above, according to the present invention, a transmission line structure capable of adjusting characteristic impedance is provided.
[Brief description of the drawings]
1A and 1B are a perspective view and a sectional view showing a transmission line structure according to an embodiment of the present invention.
2A and 2B are a cross-sectional view and a plan view showing main steps of a manufacturing method for manufacturing the transmission line structure shown in FIGS.
FIG. 3 is a cross-sectional view showing an example of mounting a transmission line structure.
4 is a perspective view showing an application example of the transmission line of FIGS. 1 and 2. FIG.
FIG. 5 is a cross-sectional view and a plan view showing an example of a transmission line structure according to a conventional technique.
FIG. 6 shows a modification of the high frequency package.
[Explanation of symbols]
1 First substrate ((100) MgO substrate)
2 Second substrate ((100) MgO substrate)
3 Air layer (vacuum layer)
5 Signal wiring (pattern of oxide superconductor layer)
6 Ground layer 7 Good conductor layer 8 Good conductor layer 9 Notch 11 First circuit board 12 Second circuit board 18 High frequency package 20 Coaxial connector 21 Center conductor 22 Ground conductor 23 Bonding wire 24 Spring 25 Indium solder 26 Metal invar layer 28 Spring 30 Screw 31 Nut 32 Piezoelectric element 33 Variable voltage source 34 High frequency package 35 Coaxial connector 37 Input port 38 Output port 40 Vacuum vessel 41 Cold plate 42 Refrigerator 43 Compressor 101 Dielectric substrate 102 Dielectric substrate 103 Bonding dielectric substrate 105 Signal Wiring 106 Ground layer

Claims (9)

A first circuit board with signal wiring formed on the surface using a superconductor layer ;
A second circuit board provided with a ground layer formed using a superconductor layer on the surface, and arranged so that the back surface of the first circuit board and the ground layer face each other;
An adjustment mechanism capable of changing a characteristic impedance of the transmission line by adjusting a distance between the first circuit board and the second circuit board;
A package containing the first circuit board and the second circuit board, including at least two coaxial connectors, and a conductor formed of a normal metal;
A transmission line structure having a cutout part that is partially deleted so that the second circuit board does not collide with the coaxial connector even if the second circuit board moves relative to the package .   The transmission line structure according to claim 1, wherein the adjustment mechanism includes a mechanism that pushes up a back surface of the second circuit board. Wherein the adjustment mechanism, the transmission line structure of claim 1 or 2, wherein including a push screw or a piezoelectric element. The transmission line structure according to claim 1, wherein a width of the notch is smaller than a diameter of an outer conductor of the coaxial connector. The signal lines and the ground layer, the transmission line structure of claim 1, further comprising a normal metal layer formed on at least a part of the surface of the superconductor layer. Said first and second circuit board MgO, LaAlO _3, transmission line structure of claim 4 or 5, wherein are formed using any of the underlying substrate sapphire. The transmission line structure according to claim 6 , wherein the base substrate has a thickness of 0.2 to 0.5 mm. The transmission line structure according to any one of claims 4 to 7 , wherein the superconductor layer has a thickness of 0.5 µm or more. Wherein the adjustment mechanism comprises a spring for pushing up the second circuit substrate rear surface, said second circuit board, according to any one of claims 4-8 having a metal invar layer for receiving said spring on the back Transmission line structure.

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