JPH0731607Y2 - Magnetostatic wave delay element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention is, for example, a VCO (voltage-controlled oscillator:
Magnetostatic wave (MSW… magne) used for voltage controlled oscillators, etc.
The present invention relates to improvement of a magnetostatic wave delay element used in a delay device.

<Prior Art> First, the magnetostatic wave and the magnetostatic wave delay element will be briefly described.

Magnetostatic wave: All electron spins in a magnetic substance are aligned in the direction when a magnetic field is applied from the outside. When a local magnetic field is applied to it, the spin also fluctuates, and the fluctuation propagates to the spins in the vicinity and propagates in the magnetic material one after another. This is called a magnetostatic wave, and its propagation speed is about 1/1000 of the speed of light, but it changes according to the strength of the magnetic field.

Magnetostatic wave delay element: When a high-frequency current is passed through one of the two transducers, the spin in the magnetic material near it propagates as a magnetostatic wave and propagates, and in the other transducer, a high-frequency induced current due to spin fluctuations. Flows. Since the propagation speed of spin fluctuations changes according to the strength of the magnetic field, the device has a variable delay time.

FIG. 7 is a perspective view showing an example of a conventional magnetostatic wave delay element. In the figure, 1 is a first substrate made of, for example, GGG (gadolinium-gallium-garnet), and 2 is a YIG (yttrium-iron-garnet) thin film formed on the front surface (back surface in the figure) of this substrate. Reference numeral 3 is a second substrate made of, for example, alumina having a slightly larger area than the first substrate, and 4a and 4b are provided on one side of this substrate with a predetermined distance (shorter than the longitudinal direction of the first substrate). It is a microstrip transducer (hereinafter, simply referred to as a transducer) composed of a conductor (thin film or coil) formed separately. These two substrates are fixed by contacting the YIG thin film 2 and the side on which the transducers 4a, 4b are formed. In the figure, the arrow indicated by H ₀ indicates the direction of the applied magnetic field, and the waveform arrow indicates the traveling direction of the magnetostatic wave. Reference numeral 5 is a ground film formed on the other surface of the second substrate. It is also possible to obtain a magnetostatic surface wave (MSSW ... Y direction) or volume backward wave (MSBVW ... X direction) by moving the position of the substrate and setting the direction of the magnetic field applied to the magnetostatic wave delay element to X or Y. However, here, only the volume forward wave (MSFVW) when a magnetic field is applied in the Z direction is targeted.

<Problems to be Solved by the Invention> When a DC magnetic field is applied from the Z (H ₀ ) direction to the magnetostatic wave delay element having the above configuration and a microwave is applied to the input transducer, the volume forward wave travels in two directions. That is, as shown by the arrow, it goes from the input transducer to the output transducer side and is captured here. It travels in the opposite direction as shown by the arrow, is reflected at the end, and is captured by the output transducer. As shown by the arrow, there is one that passes through the output transducer once and is reflected by the end and caught.

Only the volume forward wave can be effectively extracted as a signal, which causes a problem that nearly half of the microwave energy input is wasted.

In addition, the forward wave indicated by the arrow, causes ripples in the propagation characteristics.

FIG. 8 shows a magnetic field applied by a magnetic field applying device (not shown) by connecting the input / output terminals of a network analyzer (not shown) to the input / output transducer using the conventional magnetostatic wave delay element prototyped by the applicant. Is applied to propagate the volume forward wave, and its propagation characteristics are displayed on the CRT.

The size of the first prototype board (see Fig. 7) is the width l ₁
= 6 mm, length l ₂ = 13 mm, and thickness 0.5 mm, and the second substrate had a width L ₁ = 10 mm, a length L ₂ = 20 mm, and a thickness 0.63 mm. Also,
The width of the input / output transducers (strip line) was 0.05 mm, the interval L ₃ was 10 mm, and the transducers and the ground film were formed by vapor deposition of gold. The applied magnetic field was set to about 2500 (Oe).

According to the figure, the volume forward wave is captured near 1.95 GHz, 2.05, 2.15, 2.25, and 2.33 GHz, but its waveform has many ripples (the dotted line is the ideal waveform when there is no ripple). However, there is a problem that it cannot serve as a filter. Further, in the magnetostatic wave delay element having such a structure, if the delay time is to be doubled, the distance between the input transducers must be doubled, but if the shape is increased, a magnet for applying a magnetic field is also required. There was also the problem that the weight had to be increased because it had to be large.

The present invention has been made in view of the above problems of the prior art.
It is an object of the present invention to provide a magnetostatic wave delay element whose shape is relatively small even when the amount of delay is increased by reducing insertion loss and ripple.

<Means for Solving the Problems> The structure of the present invention for solving the above problems has a first substrate having a YIG thin film formed on one surface and an input / output transducer formed on one surface. Consisting of a second substrate,
The first and second substrates are fixed so that the input / output transducer and the YIG thin film are in contact with each other, and a magnetic field is applied from a direction perpendicular to the surfaces of the first and second substrates to generate a magnetostatic volume forward wave. In the magnetostatic wave delay element configured to obtain
The input / output transducers formed on the substrate are separately and linearly arranged, and the first substrate is arranged so as to straddle the input / output transducer so that the microwave input to the input transducer is It is characterized in that it is formed so as to become a magnetic wave, and a magnetostatic wave propagating from the left and right of the input transducer is reflected at the end of the first substrate and propagates to the output transducer through different paths.

<Embodiment> The present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of a magnetostatic wave delay element of the present invention. In the drawing, the same elements as those in FIG. 7 are designated by the same reference numerals and their duplicate description will be omitted, but in the present embodiment, the second substrate 3
Is formed in a substantially square shape, and input / output transducers 4a, 4b are formed in series in a diagonal direction thereof. 4c and 4d are terminal connecting portions formed at one end of the transducers. Reference numeral 10 is a through hole formed in the second substrate, and the other end of the input / output transducer is connected to the ground film formed on the back surface through this hole.

1 is a first substrate, which is formed in an octagon in this example,
The parallel planes indicated by b and a'are perpendicular to the input / output transducer, and the planes indicated by b and b'are parallel to the transducer.
The parallel planes indicated by c and c ′ are 45 ° to the transducer.
It has been fixed to be.

In the above structure, when a magnetic field is applied vertically to the substrate and microwaves are input to the input transducer as in the conventional example, the volume forward wave travels from both sides of the input transducer 4a toward the end of the first substrate. , And Ha ',
It is reflected by the H'side and goes to the output transducer. In this case, even if some of the waves pass through the output transducer like the forward wave shown in the conventional example, the capture rate of this transducer is improved. In addition, the path of the forward wave is longer than when the transducers are arranged in parallel.

FIG. 2 (a to e) shows a prototype of the magnetostatic wave delay element having the above-mentioned configuration, and the propagation characteristics are displayed on the CRT of the network analyzer by applying a magnetic field similar to the conventional one. The size of the first prototype board (see Fig. 1) is the width l ₃ =
The second substrate had a width L ₃ = 10 mm and a thickness of 0.63 mm. The width of the input / output transducers (strip line) was about 0.05 mm.

FIG. 2 (a) shows the output when the center of the side ii 'of the first substrate is placed at the center of the input / output transducer. According to this figure, the undulation is gentle and almost no ripple is observed. Absent. (B) to (c) show the first substrate in the third position.
As shown in the figure, the characteristic at each position is displayed by gradually moving in the direction of the arrow while keeping the reflection surface for the transducer at 45 °. In these figures, the number of peaks of the propagation characteristic increases as the first substrate 1 moves,
It shows that the filter characteristics can be changed arbitrarily.

4 to 6 show another embodiment. FIG. 4 shows a multi-line input / output transducer, and the generated wavelength can be specified to some extent by the width of the line interval. FIG. 5 shows a donut-shaped first substrate, and FIG. 6 shows a transducer having a desired angle so that the propagation characteristics can be changed.

Although the first substrate is illustrated as an octagon and the second substrate is illustrated as a substantially square in the present embodiment, the shape of each substrate is not limited to the illustrated example and can be changed as appropriate.

<Effects of the Invention> As described above, according to the present invention, the input / output transducers formed on the second substrate are formed individually and linearly, and the first substrate is spread over the input / output transducers. The microwave input to the input transducer becomes a magnetostatic wave, and the magnetostatic waves propagating from the left and right sides of the input transducer are reflected at the ends of the first substrate and propagate to the output transducer through different paths. Therefore, (1) If the area is the same, the propagation path can be made longer than in the conventional case, and a large delay amount can be obtained.

(2) By changing the first and second fixed positions, the filter characteristics according to the interference pattern can be arbitrarily changed even after the device is manufactured.

(3) Since forward waves propagating in two directions can be captured, power loss can be reduced.

(4) Ripple due to reflection can be reduced.

And so on.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a magnetostatic wave delay element according to the present invention, FIG. 2 is a view showing propagation characteristics by the magnetostatic wave delay element of the present invention, and FIG. 3 is a first substrate and a second board. Showing the arrangement relationship of the substrates, FIGS. 4 to 6 are diagrams showing other embodiments, and FIG.
FIG. 8 is a perspective view of a conventional magnetostatic wave delay element, and FIG. 8 is a diagram showing propagation characteristics of the conventional magnetostatic wave delay element. 1 ... First substrate, 2 ... YIG thin film, 3 ... Second substrate, 4a ...
… Input transducer, 4b …… Output transducer,
10 ... Through hole.

Claims (1)

[Scope of utility model registration request] 1. A first substrate having a YIG thin film formed on one surface thereof and a second substrate having an input / output transducer formed on one surface thereof, wherein the input / output transducer and the YIG thin film are in contact with each other. In the magnetostatic wave delay element in which the first and second substrates are fixed to and a magnetic field is applied from a direction perpendicular to the surfaces of the first and second substrates to obtain a magnetostatic volume forward wave, I / O transducers formed on the second substrate are formed individually and linearly, and
The first substrate is arranged so as to straddle the input / output transducer, the microwave input to the input transducer becomes a magnetostatic wave, and the magnetostatic wave propagating from the left and right of the input transducer is an edge of the first substrate. A magnetostatic wave delay element, characterized in that the magnetostatic wave delay element is formed so that it is reflected by a portion and propagates to the output transducer through different paths.