JPH0756922B2 - Magnetostatic wave device - Google Patents

Description

The present invention relates to a magnetostatic wave device, and more particularly to a magnetostatic wave device used as, for example, an MSW filter.

(Prior Art) A conventional magnetostatic wave device in which a YIG (yttrium, iron, garnet) thin film is formed on a GGG (gadolinium, gallium, garnet) substrate, and two antennas or transducers are formed on the YIG thin film. was there.

(Problems to be Solved by the Invention) However, in such a conventional magnetostatic wave device, since the electromagnetic wave radiated from one transducer to the other transducer becomes a loss, the insertion loss is large.

Therefore, the inventors of the present application have devised a magnetostatic wave device having a small insertion loss.

2A and 2B respectively show an example of a magnetostatic wave device which is the background of the present invention and which the inventors of the present invention have devised, FIG. 2A is an exploded perspective view thereof, and FIG. 2B is a sectional view thereof. Is. In this magnetostatic wave device 1, YIG (yttrium, iron, garnet) thin films 3a and 3b are formed on one main surface of two GGG (gadolinium, gallium, garnet) substrates 2a and 2b by epitaxial growth by a liquid phase method or the like. It Furthermore, on one YIG thin film 3a, transducers 4a and 4b are formed at intervals by a method such as vapor deposition, and further, a disk-shaped metal layer 5 is formed between the transducers 4a and 4b. There is. And those transducers 4a and
4b or the metal layer 5 is sandwiched between two YIG thin films 3a and 3b.

In this magnetostatic wave device 1, since the YIG thin films 3a and 3b are present on both sides of the transducers 4a and 4b, the loss of electromagnetic waves radiated from the transducer is reduced, and therefore the insertion loss is reduced to some extent. Further, in the magnetostatic wave device 1, since the metal layer 5 is present between the transducers 4a and 4b, the Q value at the resonance frequency is large and the spurious mode separation is improved as compared with the conventional magnetostatic wave device.

However, it is desired to further reduce the insertion loss in the magnetostatic wave device.

Therefore, a main object of the present invention is to provide a magnetostatic wave device having a smaller insertion loss.

(Means for Solving the Problem) The present invention relates to two YIG thin films to which a DC magnetic field is applied,
A low dielectric constant layer made of a low dielectric constant dielectric material formed between two YIG thin films, and two transducers formed at a distance between the two YIG thin films and the low dielectric constant layer, It is a magnetostatic wave device.

(Operation) In this magnetostatic wave device, the two transducers have two
Since it is sandwiched between the YIG thin film and the low dielectric constant layer, the propagation loss is small.

(Effect of the Invention) According to the present invention, since the propagation loss is reduced, the insertion loss of the magnetostatic wave device is further reduced.

According to the inventor's experiment, in the embodiment of the present invention, compared with the magnetostatic wave device shown in FIGS. 2A and 2B using YIG thin film of the same size, the propagation loss is reduced by 20 to 30%, Accordingly, the insertion loss also decreased.

The above-mentioned objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of the embodiments with reference to the drawings.

(Embodiment) FIGS. 1A to 1C respectively show an embodiment of the present invention, FIG. 1A is an exploded perspective view thereof, FIG. 1B is a plan view thereof, and FIG. FIG. 1B is a cross-sectional view taken along the line IC-IC of FIG. 1B.

The magnetostatic wave device 10 includes two thin rectangular YIG (yttrium, iron, garnet) thin films 12a and 12b. These YIG thin films 12a and 12b are GGG substrates 14a made of GGG (gadolinium, gallium, garnet) single crystal.
And 14b are formed on one main surface by epitaxially growing a YIG single crystal by a method such as a liquid phase method.

Further, a low dielectric constant layer 16 is formed between these YIG thin films 12a and 12b with a dielectric material having a low dielectric constant such as ceramics or resin.

Further, strip lines 18a and 20a are formed as antennas or transducers on the surface of one YIG thin film 12a or one main surface of the low dielectric constant layer 16 at intervals in the longitudinal direction thereof. A disk-shaped metal layer 22a is formed between 18a and 20a. These strip lines 18a, 20a and the metal layer 22a
Is formed by a method such as vapor deposition. Similarly, the strip lines 18a, 20a and the metal layer 22a are formed on the surface of the other YIG thin film 12b or the other main surface of the low dielectric constant layer 16.
Corresponding to strip lines 18b, 20b and metal layer 22b
Is formed.

Therefore, striplines 18a and 20a are
It is sandwiched between the YIG thin film 12a and the low dielectric constant layer 16, and the strip lines 18b and 20b are sandwiched between the other YIG thin film 12b and the low dielectric constant layer 16.

Further, the low dielectric constant layer 16 has a large number of through holes in the portions where the strip lines 18a and 18b are formed, the portions where the strip lines 20a and 20b are formed, and the portions where the metal disks 22a and 22b are formed. Holes 16a, 16b and 16c are formed, and connection electrodes are formed in the through holes 16a to 16c. And these through holes 16a-16c
The strip lines 18a and 18b, the strip lines 20a and 20b, and the metal layers 22a and 22b are electrically connected to each other through the internal connection electrodes.

Further, ground electrodes 24a and 24b made of, for example, metal are formed on the other main surfaces of the GGG substrates 14a and 14b, respectively.

In this magnetostatic wave device 10, for example, YIG thin films 12a and 12
A DC magnetic field is applied in a direction orthogonal to the main surface of b for use. And, for example, striplines 18a and 1
Strip line 18a and 18b
Volume forward magnetostatic wave (MSFV
W) is excited. Further, this volume-advancing magnetostatic wave is generated on the two YIG thin films 12a and 12b by the strip line 18a and
Propagation from 18b to the strip lines 20a and 20b side. The propagated volumetric magnetostatic wave is then received at striplines 20a and 20b. Therefore, in the magnetostatic wave device 10, compared with the conventional magnetostatic wave device, the electromagnetic wave generated from the transducer can be effectively used, so that the insertion loss becomes small and the Q value becomes large. Further, since the transmission loss of the transducer as a stripline is also reduced, there is an effect that the insertion loss is reduced.

According to the experiment by the inventor, in the magnetostatic wave device 10, the strip lines 18a, 18b, 20a and 20b have YIG thin films 12a and 12b.
Since it is sandwiched between b and the low dielectric constant layer 16, the propagation loss is 20 to 30% smaller than that of the magnetostatic wave device shown in FIGS. 2A and 2B using YIG thin films of the same size. And accordingly, the insertion loss also decreased.

Further, in the magnetostatic wave device 10 of this embodiment, similar to the magnetostatic wave device shown in FIGS. 2A and 2B, since the metal layers 22a and 22b are formed between the strip lines, such a metal layer The Q value at the resonance frequency is large and the separation of the spurious modes is improved as compared with the conventional magnetostatic wave device which does not have the same. However, in the present invention, such metal layers 22a and 22b or the through holes 16c for connecting them may not be formed.

The magnetostatic wave device 10 may apply a magnetic field in a direction parallel to the YIG thin films 12a and 12b and perpendicular to the propagation direction of the magnetostatic wave. In this case, the surface magnetostatic wave (MSSW) is propagated on the two YIG thin films 12a and 12b. Alternatively, the magnetic field may be applied in a direction parallel to the YIG thin films 12a and 12b and parallel to the magnetostatic wave propagation direction. In this case, the volume receding magnetostatic wave (MSBVW) is propagated on the YIG thin films 12a and 12b. In this way, the direction of the magnetic field applied to the magnetostatic wave device 10 may be arbitrarily changed.

[Brief description of drawings]

1A to 1C respectively show an embodiment of the present invention, FIG. 1A is an exploded perspective view thereof, FIG. 1B is a plan view thereof, and FIG. 1C is a line of FIG. 1B. It is sectional drawing in IC-IC. 2A and 2B respectively show an example of a magnetostatic wave device which is the background of the present invention and which the inventors of the present invention have devised, FIG. 2A is an exploded perspective view thereof, and FIG. 2B is a sectional view thereof. Is. In the figure, 10 is a magnetostatic wave device, 12a and 12b are YIG thin films, 16 is a low dielectric constant layer, and 18a, 18b, 20a and 20b are strip lines.

Claims (1)

[Claims] 1. A YIG thin film to which a DC magnetic field is applied, a low dielectric constant layer made of a dielectric material having a low dielectric constant formed between the two YIG thin films, and the two YIG thin films and the low dielectric constant. A magnetostatic wave device including two transducers spaced apart from a layer.