JPH0685507A - Magnetstatic microwave device - Google Patents

Abstract

PURPOSE:To provide the high-performance device provided with a high Q value without lowering the entire impedance by using a magnetostatic resonance element which is slender vertically in the current direction of microwaves and is provided with a ratio between the long side and the short side larger than a specified value. CONSTITUTION:This device is composed of a magnetostatic wave resonating element 1 in the shape of a rectangular thin plate, microstrip line 2 which terminal is short- circuited, and ground conductor 3. Then, an external magnetic field Hext is vertically impressed to the plane of the thin plate so as to generate ferrimagnetic resonance. In this case, the ratio between the long side and short side of the magnetostatic wave element 1 in the shape of the rectangular thin plate is set >=1.5. This is because the change of a ferrimagnetic resonance half value width is considerable on the condition of W/Lo <1.5, when the length of the magnetostatic wave element in the microwave current direction is defined as Lo and the width is defined as W, and the change is turned to an almost fixed low value on the condition of W/Lo >=1.5. Thus, the magnetostatic wave element 1 can be regarded as a centralized constant element for the microwave circuit, and the YIG film of large volume can be built across so as to provide the high impedance while keeping the high Q value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetostatic wave microwave device having a magnetostatic wave element utilizing ferrimagnetic resonance and means for exciting the magnetostatic wave.

[0002]

2. Description of the Related Art As a magnetostatic wave microwave device, GGG is used.
Liquid phase epitaxial growth of YIG (yttrium, iron, garnet) thin film, which is a ferrimagnetic material, on a (gadolinium, gallium, garnet) non-magnetic substrate (hereinafter referred to as LPE).
The processed YIG thin film is processed into a desired shape such as a circular shape or a rectangular shape by selective etching or mechanical processing using fattolithography technology, and by utilizing these ferrimagnetic resonance, a magnetostatic wave microwave device such as a filter or an oscillator is used. Are proposed. These magnetostatic microwave devices have an advantage that a microwave integrated circuit can be manufactured using a microstrip line or the like as a transmission line, and hybrid connection with other microwave integrated circuits can be easily performed. . Further, the magnetostatic wave device by ferrimagnetic resonance of the YIG thin film is
Since it can be produced by LPE and processing techniques as described above, it is excellent in mass productivity. As described above, the magnetostatic wave microwave device using the YIG thin film magnetostatic wave element is the same as the conventional YIG thin film magnetostatic wave device.
It has many practical advantages compared to those using spheres. That is, the performance of the magnetostatic wave microwave device using the ferrimagnetic resonance of the YIG thin film is greatly influenced by the geometrical shape of the YIG thin film. In particular,
In order to obtain a large impedance, a large YIG thin film having a large area and a large film thickness is required. This is a big design problem when not only miniaturizing the microwave circuit but also maintaining high performance. FIG. 6 is a structural diagram of a magnetostatic wave microwave device using a rectangular thin plate magnetostatic wave element 1 according to the related art. The rectangular thin magnetostatic wave element 1 is mounted between the microstrip line 2 and the ground conductor 3 which are short-circuited at the terminal end. An external magnetic field Hext is applied perpendicularly to the plane of the thin plate to cause ferrimagnetic resonance. In the prior art, the size relationship between the two sides Lo and W of the rectangular type is almost the same, and most of them are close to a square. A part of the already-published article (USP4782312) describes an elongated shape, but the importance of the relationship between the long side and the short side is not mentioned at all. In the configuration so far, when an attempt is made to increase the impedance R at the time of resonance seen from the input side of the microstrip line,
A method has been adopted in which the dimensions Lo, W, and t of the magnetostatic wave device 1 are increased at the same time. Originally, as shown in FIG. 8, the magnetostatic wave element 1 is an ideal equivalent circuit in which a lumped constant type LC parallel resonator is connected to a portion separated from the input terminal by d. However, in the conventional method for obtaining high impedance, the length of Lo cannot be ignored with respect to the wavelength, and as shown in FIG. 9, an equivalent circuit in which innumerable resonators are distributed and connected between Lo. Becomes This corresponds to observing a plurality of resonators excited by microwaves having different phases at the same time, which leads to the drawback that the original high Q value of the magnetostatic wave resonant element cannot be extracted to the outside. On the contrary, if Lo, W, and t are reduced at the same time in order to obtain a high Q value, the Q value is improved, but the energy of the magnetostatic wave element with respect to the total microwave energy is reduced.
This is not preferable because the minutes are reduced. That is, in terms of an electric circuit, this corresponds to a significant decrease in impedance at resonance. FIG. 7 is a structural diagram of a magnetostatic wave microwave device using a circular thin plate magnetostatic wave element according to the related art. Even in this configuration, the relationship described above does not change. That is, when the outer diameter D and the thickness t are increased in order to obtain the impedance at the time of high resonance, the Q value of the magnetostatic wave element decreases and the high Q
If D and t are reduced in order to obtain the desired value, the impedance at resonance is reduced.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and provides a magnetostatic microwave device capable of realizing a high impedance while maintaining a high Q value. It is intended to be provided.

[0004]

According to the magnetostatic wave microwave device of the present invention, the rectangular thin plate magnetostatic wave element has a ratio of the long side to the short side of 1.5 or more, and the magnetostatic wave It is characterized in that the direction of the current flowing through the outer conductor provided on the element is orthogonal to the long side.

[0005]

According to the above construction, the magnetostatic wave element can be regarded as a lumped element on the microwave circuit, and a large volume YI is required to obtain a high impedance while maintaining a high Q value.
A G membrane can be mounted.

[0006]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a diagram for explaining the basic configuration of the present invention. In the figure, the rectangular-shaped 1 is a magnetostatic wave resonance element, Lo is the length of the magnetostatic wave element 1 in the microwave current direction, and W is its width. 2 is a microstrip line for terminating short circuit, 4 is the direction of microwave current flowing therethrough, 3 is a ground conductor, and 4'is the direction of microwave current flowing through the ground conductor. An external magnetic field Hext is applied perpendicular to the plane of the thin plate in order to generate ferrimagnetic resonance. As shown in the figure, in the configuration of the present invention, W is about 2 of Lo, unlike the prior art of FIG.
There is almost double the width. FIG. 2 is a diagram showing an embodiment of the present invention. As the magnetostatic wave element 1, a YIG thin film 1'is formed on a GGG substrate by LPE. Figure 3
Is the area of the YIG thin film 1'with the configuration of FIG.
5G when changing W / Lo with 0 mm ² kept constant
It is the measurement result of the ferrimagnetic resonance half-value width ΔH in the Hz band. The YIG thin film 1'has a constant film thickness of 20 μm.
When W / Lo is 1 or less, ΔH increases to 20 Oe, but ΔH tends to decrease as W / Lo increases. In particular, when W / Lo <1.5, the change in ΔH is large. However, it can be seen that when W / Lo ≧ 1.5, the material properties are close to a substantially constant low value ΔH = 0.75 Oe. The ΔH described here corresponds to the reciprocal of the Q value of the magnetostatic wave microwave device of the present invention, and the smaller the ΔH is, the higher the Q value is obtained. Therefore, the range of the present invention is W / Lo.
It can be understood from FIG. 3 that ≧ 1.5 can be defined. Figure 4
Shows another embodiment of the present invention. YIG film 1'having a large W / Lo, that is, elongated in the direction perpendicular to the microwave current
In order to improve the coupling of the microwaves, a plurality of electrode fingers 7 are distributed in the width direction on the YIG film 1 ', and a metal thin film electrode having pads 6 and 6'at the ends is formed. The input microstrip line 2a is connected to the pad 6, and the short-circuited microstrip line 2b is connected to the pad 6 '. With this configuration, a high impedance magnetostatic wave microwave device having a higher Q value can be realized. FIG. 5 shows another embodiment of the present invention. An open stub 8 is connected instead of the short-circuited microstrip line 2b.
This is designed so that the electrical length from the center of the wide YIG thin film 1 ′ to the open end of the open stub 8 is λ / 4. As a result, the center of the wide YIG thin film 1'is always electrically maximum in current, that is, equivalent to a short circuit state.

[0007]

According to the present invention, as compared with the prior art, since the magnetostatic wave resonant element elongated in the direction perpendicular to the current direction of the microwave is used, the overall impedance is not lowered. A high-performance magnetostatic wave microwave device having a high Q value can be provided.

[Brief description of drawings]

FIG. 1 is a structural diagram showing an embodiment of the present invention.

FIG. 2 is a structural diagram showing an embodiment of the present invention.

FIG. 3 is a structural diagram showing an embodiment of the present invention.

FIG. 4 is a structural diagram showing an embodiment of the present invention.

FIG. 5 is a structural diagram showing an embodiment of the present invention.

FIG. 6 is a structural diagram of a prior art.

FIG. 7 is a structural diagram of a prior art.

FIG. 8 is a diagram showing an equivalent circuit of a magnetostatic wave device.

FIG. 9 is an equivalent circuit diagram illustrating a problem of the conventional technique.

[Explanation of symbols]

 1 rectangular thin plate magnetostatic wave element 1'YIG thin film 2 microstrip line 3 ground conductor 4 microwave current direction 5 GGG substrate 6 pad 7 electrode finger 8 open stub

Claims (2)

[Claims] 1. A rectangular thin plate magnetostatic wave device having a ratio of a long side to a short side of 1.5 or more, and a direction of a current flowing through an external conductor provided on the magnetostatic wave device. Is orthogonal to the long side, a magnetostatic wave microwave device. 2. The magnetostatic wave microwave device according to claim 1, wherein the thin plate magnetostatic wave element is a ferrimagnetic thin film containing YIG (yttrium, iron, garnet) as a main component.