JP2508281B2 - High temperature superconducting microstrip line - Google Patents

Description

The present invention relates to a microstrip line using a high temperature superconductor.

[Conventional technology]

In recent years, the discovery of high-temperature superconductors has led to active research and development on various applications of these superconductors. In the field of microwave and millimeter wave, development of a microstrip line using a high temperature superconductor is in progress in order to reduce the loss of the transmission line.

FIG. 2 is a diagram showing a conventional high temperature superconducting microstrip line, in which (a) is a sectional view and (b) is a perspective view. Such a conventional example is shown, for example, in the 1989 IEICE Spring National Conference Proceedings 5-67 (lecture number C-67). In FIG. 2, a microstrip conductor 2 made of YBa ₂ Cu ₃ O _{7 is formed} on a substrate 1 made of MgO or SrTiO ₃ .
And the ground electrode 3 made of YBa ₂ Cu ₃ O ₇ is provided on the lower surface of the substrate 1. Not only yttrium-based, but also thallium-based and bismuth-based high-temperature superconductor thin films can be obtained as good thin films on MgO or SrTiO ₃ substrates. However, the dielectric loss tangent of these substrates is 1 × 10 ^{−5 to} 5 × 10 ^−4.
There is a degree.

[Problems to be Solved by the Invention]

In the case of the microstrip line having the structure shown in FIG. 2, the conductor loss is extremely small because the conductor is a superconductor, but the electric flux lines 4 are present in the substrate 1, so that a large dielectric loss is caused. Cause Therefore, a strip line with low transmission loss could not be obtained.

It is an object of the present invention to provide a microstrip line having extremely low dielectric loss by using a substrate made of MgO or SrTiO _{3 which} can form a good high temperature superconductor thin film.

[Means for solving the problem]

High-temperature superconducting microstrip line of the present invention, the first high-temperature superconductor and the thin film, a second substrate made of MgO or SrTiO ₃ formed in stripes on a first substrate made of MgO or SrTiO ₃ The second high temperature superconductor thin film formed on the first high temperature superconductor thin film, the first high temperature superconductor thin film and the second high temperature superconductor thin film facing each other with a constant distance. A substrate supporting the substrate and the second substrate, wherein the first high-temperature conductor thin film is used as a microstrip conductor, and the second high-temperature superconductor thin film is used as a ground conductor. It has a feature.

[Action]

In the present invention, since the superconducting microstrip conductor and the superconducting ground conductor face each other with air or the like interposed therebetween,
Dielectric loss can be made extremely small. As a result, for example, regarding a microstrip line having a characteristic impedance of 50Ω, a transmission loss of 0.001 dB or less per cm at 10 GHz can be realized.

〔Example〕

FIG. 1 is a diagram showing a high temperature superconducting microstrip line of an embodiment of the present invention, (a) is a sectional view and (b) is a perspective view. In FIG. 1, YBa ₂ Cu ₃ O ₇ formed in a stripe shape in contact with a substrate 11 made of MgO or SrTiO ₃
The high-temperature superconductor thin film 13 made of Y and the high-temperature superconductor thin film 14 made of YBa ₂ Cu ₃ O ₇ formed in contact with the substrate 12 made of MgO or SrTiO ₃ face each other with the air 16 interposed therebetween. These substrates 11 and 12 are supported by a side surface support insulator 15.

In the high temperature superconducting microstrip line having such a structure, the high temperature superconductor thin film 13 constitutes a microstrip conductor, the high temperature superconductor thin film constitutes a ground conductor, and the electric force lines 17 are present in the air 16. ing. The characteristic impedance Z _o of this microstrip line is It is expressed as In the equation (1), W is the width of the microstrip conductor 13, S is the distance between the microstrip conductor 13 and the ground conductor 14, μ _r is the relative magnetic permeability, μ _o and ε _o are the magnetic permeability in vacuum and the dielectric constant, respectively. The ratio, T is the thickness of the high temperature superconductor thin films 13 and 14, and λ is the penetration length of London. In equation (1)
T / λ >> 1, μ _r = 1, ε _r = 1, S = 100 μm, W = 700 μm, λ = 0.15
If μm, then Z _o ≈50Ω.

In the above examples, YBa ₂ Cu ₃ O ₇ which is a high temperature superconductor was used for the superconductor thin film, but the superconductor is not limited to the yttrium system, and the thallium system and the bismuth system also contain MgO and SrTiO 3. it is possible to grow a good thin film ₃ on a substrate, it may of course be used these superconductors.

The space between the superconducting strip conductor and the ground conductor may not be air, may be vacuum, or may be filled with liquid nitrogen or the like.

[Advantages of the Invention] In the high-temperature superconducting microstrip line of the present invention, the electric lines of force are present in the air, for example, so that the dielectric loss is extremely small, and in addition, since the superconductor is used, the conductor loss is also extremely small. There is. Therefore, a transmission loss of 0.001 dB or less per cm can be realized, which is of great significance for microwave and millimeter wave engineering.

[Brief description of drawings]

FIG. 1 shows a high temperature superconducting microstrip line according to an embodiment of the present invention, and FIG. 2 shows a conventional high temperature superconducting microstrip line. 1,11,12 …… Substrate 2,3,13,14 …… High temperature superconductor thin film 4,17 …… Line of electric force 15 …… Side support insulator 16 …… Air

Claims (1)

(57) [Claims] 1. A first high temperature superconductor thin film formed in stripes on a first substrate made of MgO or SrTiO ₃ and a second high temperature superconductor thin film made on a second substrate made of MgO or SrTiO ₃ . Said high temperature superconductor thin film, said first high temperature superconductor thin film and said second high temperature superconductor thin film face each other with a constant distance.
A substrate for supporting the second substrate and a support for supporting the second substrate, wherein the first high temperature conductor thin film is used as a microstrip conductor, and the second high temperature superconductor thin film is used as a ground conductor. High-temperature superconducting microstrip line.