JPH05199024A - Microwave resonator - Google Patents

Abstract

PURPOSE:To easily adjust a resonance frequency by arranging a resonance conductor in a way that a microwave propagating through the conductor is invaded in an electromagnetic field formed by the microwave and providing a conductor piece, a dielectric chip or a magnetic chip whose invasion quantity is adjusted to the resonator. CONSTITUTION:A brass made screw 60 is screwed through a cover 50b of a microwave resonator. A tip of the screw 60 is invaded up to the vicinity of a superconducting resonance conductor 10. The tip of the screw 60 is made close or remote to/from the superconducting resonance conductor 10 by turning the screw head. The electromagnetic field characteristic of the resonance circuit comprising the superconducting resonance conductor 10, the superconducting ground conductor 30 and the package 50a is changed by the turning of the screw 60. As a result, the resonance frequency of the microwave resonator is changed.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to microwave resonators. More specifically, the present invention relates to a novel structure of a microwave resonator including a conductor line formed of a composite oxide superconductor thin film.

[0002]

2. Description of the Related Art Electromagnetic waves having a wavelength of several tens of centimeters to several millimeters and called microwaves or millimeter waves are theoretically only a part of the electromagnetic spectrum, but from an engineering point of view, It is often considered independently because of the development of unique methods and devices for handling.

On the other hand, since it was reported in 1986 that [La, Ba] ₂ CuO ₄ exhibited a superconducting state at 30 K by Bednots, Mueller, etc., in 1987, the superconducting critical temperature Tc in the 90 K range was observed by Chu. YBa ₂ Cu ₃ O _y has been reported, and in 1988, Maeda et al. Reported a so-called Bi-based complex oxide superconducting material exhibiting a critical temperature of 100 K or higher. These series of complex oxide superconducting materials are
Since the superconducting phenomenon can be realized by cooling with inexpensive liquid nitrogen, the possibility of wider practical application of the superconducting technology has been suddenly investigated.

Microwave devices are no exception in that the phenomena peculiar to superconductivity act advantageously. That is, for example, in a strip line, the attenuation constant due to the resistance of the conductor increases in proportion to the square root of the frequency. Although the dielectric loss also increases in proportion to the increase in frequency, in the recent strip line, the loss of the strip line is due to the resistance of the conductor layer, especially in the region of 10 GHz or less due to the improvement of the dielectric material. Things make up the majority. Therefore, reducing the resistance of the conductor layer in the strip line significantly improves the performance of the microwave line.

Further, the strip line can be used not only as a simple transmission line but also as a microwave device such as an inductance element, a filter, a resonator, a delay line or the like by performing appropriate patterning. Therefore, the improvement of the strip line directly leads to the improvement of the characteristics of these microwave devices. Therefore, various microwave devices in which the conductor line is formed of an oxide superconductor have been proposed.

FIG. 2 is a diagram showing a configuration example of a microwave resonator using the above oxide superconductor.

As shown in FIG. 2 (a), this microwave resonator includes a first substrate 20 on which a superconducting resonance conductor 10 formed of an oxide superconductor thin film having a predetermined pattern is mounted, and also an oxide superconducting conductor. The second substrate 40 on which the superconducting ground conductor 30 formed of the body thin film is mounted,
After being housed in a stack, the package 50a is sealed by the covers 50b and 50c.

In this microwave resonator, the dimensions of the first substrate 20 and the second substrate 40 are different from each other, and a step 51 is formed on the inner surface of the package 50a correspondingly.
The second substrate 40 is larger than the first substrate 20 in size. Therefore, the superconducting ground conductor 30 mounted on the second substrate 40 is in contact with the step of the package 50a at its peripheral portion.

Although not shown, in practice, lead wires for introducing microwaves to the resonance conductor 10 are provided through the package 50a or the cover 50b.

FIG. 2B is a diagram showing a pattern of the superconducting resonance conductor 10 formed on the first substrate 20 used in the microwave resonator shown in FIG. 2A.

As shown in the figure, on the first substrate 20, a circular superconducting conductor 11 having a diameter of 12 mm, which serves as a resonator, and a pair for introducing or leading a microwave to or from the superconducting conductor 11. Superconducting conductor lines 12 and 13 are formed.
These superconducting resonance conductors 11 and superconducting conductor lines 12, 13
The superconducting ground conductor 30 on the second substrate 40 is made of Y-Ba-Cu.
It can be formed by an oxide superconductor thin film which is a complex oxide such as.

The microwave resonator having the above structure is
Depending on the characteristics of the superconducting resonance conductor 11, a specific resonance frequency f
_It has ₀ , and can be used for frequency control of a local oscillator of a microwave communication device.

[0013]

However, there is a problem that the resonance frequency f ₀ of the actually manufactured microwave resonator does not always meet the design specification. That is, a microwave resonator manufactured using an oxide superconductor thin film inevitably has characteristic variations due to mutual influences of slight changes in the characteristics of the oxide superconductor thin film and slight errors during assembly. Occurs.

Therefore, the present invention provides a novel microwave resonator capable of easily adjusting the resonance frequency in order to solve the above-mentioned problems of the prior art and to correct the characteristic variation as described above. The purpose is to do.

[0015]

According to the present invention, in a microwave resonator constituted by a superconducting resonance conductor formed of an oxide superconductor thin film and a superconducting ground conductor, a microwave flowing through the resonance conductor is Provided is a microwave resonator, which is arranged so as to be capable of penetrating into an electromagnetic field to be formed and is provided with a conductor piece, a dielectric piece, or a magnetic piece capable of adjusting the amount of penetration.

[0016]

The microwave resonator according to the present invention is characterized mainly in that it has a function of changing its resonance frequency f ₀ .

That is, when microwaves propagate through the microstrip line, an electric field is formed between the ground conductor and the conductor line, and at the same time, a magnetic field is formed around the conductor line. When a conductor, a dielectric or a magnetic material is inserted into this electromagnetic field, the electromagnetic characteristics of the resonator change.

The conductor piece, the dielectric piece or the magnetic piece for changing the resonance frequency is not particularly limited in shape and material as long as it is a conductor, a dielectric body or a magnetic body. It can be easily attached by using a package or cover. However, in order not to reduce the Q value of the resonator, it is advantageous to use a conductor piece made of a superconductor.

The superconducting conductor layer and the superconducting ground conductor layer in this microwave resonator can be formed of a composite oxide superconducting thin film of Y-based, Bi-based, Tl-based or the like.
Further, as the film forming method, any known film forming method such as a sputtering method and a laser vapor deposition method can be used.

Hereinafter, the present invention will be described in more detail with reference to examples, but the following disclosure is merely an example of the present invention and does not limit the technical scope of the present invention.

[0021]

[Embodiment 1] FIG. 1 is a diagram showing a specific configuration example of a microwave resonator according to the present invention. Note that FIG.
The common reference numerals are attached to the components common to the conventional microwave resonator shown in (a).

As shown in the figure, the microwave resonator is basically the same as the conventional microwave resonator shown in FIG. 2 (a), and a cover 59b is further penetrated. Then, a screw 60 that is screwed on is added.

Here, the screw 60 is made of brass, and its tip penetrates to the vicinity of the superconducting resonance conductor 10. Further, the screw 60 is configured such that the tip of the screw 60 can be moved toward or away from the superconducting resonance conductor 10 by rotating the screw head.

By operating the screw 60 as described above, the electromagnetic field characteristic of the resonance circuit constituted by the superconducting resonance conductor 10, the superconducting ground conductor 30 and the package 50b is changed, and the resonance frequency f ₀ of this microwave resonator is changed. Can be changed.

[Manufacturing Example 1] A microwave resonator having the structure shown in FIG. 1 was actually manufactured.

As the first substrate 20, a MgO substrate having a side of 18 mm and a thickness of 1 mm is used. The resonant conductor 10 has a thickness of
It was formed by a 5000Å Y-Ba-Cu composite oxide thin film.

Further, the superconducting resonance conductor 10 serving as a resonator is
A circular superconducting conductor disk 11 having a diameter of 12 mm was used, and the pair of superconducting conductor lines 12 and 13 had a width of 1.0 mm and a length of 1.5 mm. still,
The distance between the waveguides 12 and 13 and the resonator 11 was set to 1.5 mm at the closest point.

On the other hand, as the second substrate 40, a MgO substrate having a side of 20 mm and a thickness of 1 mm is used, and the thickness is 50 mm.
The ground conductor 30 was formed from a 00-Å Y-Ba-Cu composite oxide thin film.

The two substrates 20 and 40 as described above are housed in a brass package 50a, and a brass cover 50 is also used.
The package 50a was sealed by b and 50c.

Further, a screw hole for inserting the screw 60 is formed at the center of the cover 50a, and the M4 (ISO) brass screw 60 is attached to the screw hole.

The resonance frequency at 77K of the superconducting microwave resonator manufactured as described above was measured. The measurement result is shown in FIG.

[Embodiment 2] FIG. 4 is a view showing another preferred embodiment of the superconducting microwave resonator according to the present invention. In the figure, the same reference numerals are given to the constituent elements common to the first embodiment.

As shown in the same figure, this microwave resonator is the same as the microwave resonator shown in FIG.
A superconducting conductor piece (not visible in FIG. 1) and a cover 62 for holding the superconducting conductor piece are mounted.

FIG. 5 is an enlarged view of the screw 60 in the superconducting microwave resonator shown in FIG.

As shown in the figure, the superconducting conductor piece 61 uses a substrate 61b loaded with the same oxide superconducting thin film 61a as that constituting the microwave line 10 or 30. Also, the cover 62 is made of the same brass as the screw 60,
It has a function of fixing the superconducting conductor piece 61 to the tip of the screw 60 and at the same time electrically connecting the superconducting thin film 61a to the screw 60 for grounding.

With the above structure, the screw 60 is operated from the outside of the microwave resonator to change the amount of penetration of the superconducting conductor piece 61, so that the superconducting resonance conductor 10, the superconducting ground conductor 30 and the package 50b are controlled. The electromagnetic field characteristics of the constituted resonance circuit change, and the resonance frequency f ₀ of this microwave resonator can be changed.

[Manufacturing Example 2] A microwave resonator having the structure shown in FIGS. 4 and 5 was actually manufactured and its characteristics were measured.

As the superconducting conductor piece 61, Y ₁ Ba ₂ Cu ₃ O _{7-x is used.}
The MgO substrate 61b loaded with the thin film 61a was processed into a disk shape having a diameter of 8 mm. The Y ₁ Ba ₂ Cu ₃ O _7-x thin film 61a
For the film forming method, film forming conditions, film thickness, etc., refer to
It was the same as the oxide superconducting thin film constituting 10.

As the cover 62, a brass rod is used as a material, the inner diameter of the threaded portion is 10 mm, and the MgO substrate 61 is used.
The inner diameter of the tip portion that accommodates b is 8 mm, and the inner diameter of the flange portion formed at the lower end so that the MgO substrate 61b does not fall off
What was processed so that it might become 7.5 mm was used.

Further, as a comparative object for evaluating the performance of the microwave resonator according to the present invention, Y ₁ Ba ₂ Cu ₃ O is used.
A microwave resonator using an Au thin film instead of the _7-x thin film 61a was manufactured, and its characteristics were measured under the same conditions as in the above manufacturing example. The thickness of the Au thin film loaded on the substrate 61b was 10 μm.

In the pair of microwave resonators manufactured as described above, the Q value when the distance between the tip of the cover 62 and the microwave resonance conductor 10 is 8 mm and the Q value when the distance is 2 mm and the resonance frequency is 2 mm. The value and the resonance frequency were measured respectively. The measurement results are also shown in Table 1.

[0042]

[Table 1]

As can be seen from the measurement results shown in Table 1, when the superconducting conductor piece is used as the conductor piece to penetrate into the microwave resonator, the Q value is stable regardless of the change of the resonance frequency.

[0044]

As described above, the microwave resonator according to the present invention is constructed so that its resonance frequency f ₀ can be easily adjusted. Also, even if the resonance frequency is changed by using an appropriate conductor piece, Q
The value is stable.

Therefore, it can be very advantageously used for a local oscillator of a microwave communication device, for example.

[Brief description of drawings]

FIG. 1 is a diagram showing a specific configuration example of a microwave resonator according to the present invention.

FIG. 2 is a diagram showing a typical configuration of a conventional microwave resonator using an oxide superconductor thin film.

FIG. 3 is a graph showing the measurement results of the resonance frequency at 77K of the microwave resonator according to the present invention.

FIG. 4 is a view showing another preferred embodiment of the superconducting microwave resonator according to the present invention.

5 is an enlarged view showing a configuration of a screw 60 in the superconducting microwave resonator shown in FIG.

[Explanation of symbols]

10 superconducting resonance conductor, 20 first substrate, 30 superconducting ground conductor, 40 second substrate, 50a package, 60 screw

Claims (2)

[Claims] 1. A microwave resonator including a superconducting resonance conductor formed of an oxide superconductor thin film and a superconducting ground conductor, wherein the microwave can further penetrate into an electromagnetic field formed by a microwave flowing through the resonance conductor. A microwave resonator provided with a conductor piece, a dielectric piece, or a magnetic piece that is arranged and whose amount of penetration can be adjusted. 2. The microwave resonator according to claim 1, wherein the conductor piece whose penetration amount can be adjusted is a superconducting conductor piece connected to ground.