Wave transmission lines and networks – Coupling networks – Wave filters including long line elements
Reexamination Certificate
2000-11-28
2003-02-11
Pascal, Robert (Department: 2817)
Wave transmission lines and networks
Coupling networks
Wave filters including long line elements
C428S692100
Reexamination Certificate
active
06518862
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetostatic wave element. More specifically, it relates to a magnetostatic wave element which, for example, converts microwaves into magnetostatic waves which propagate through a single crystal magnetic garnet film and further converts the magnetostatic waves into microwaves for output, as well as to a manufacturing method therefor.
2. Description of the Related Art
FIG. 1
is an illustrative view showing an example of a magnetostatic wave element which is art related to the present invention. A magnetostatic wave element
10
contains a non-magnetic substrate
12
. A gadolinium-gallium-garnet (GGG) substrate or the like is used as the non-magnetic substrate
12
, for example. A single crystal magnetic garnet film
14
is formed on the non-magnetic substrate
12
. An yttrium-iron-garnet (YIG) film or the like is used as the single crystal magnetic garnet film
14
. Furthermore, two microstrip lines
16
and
18
are formed on the single crystal magnetic garnet film
14
at a specific distance apart. Microstrip line
16
is used for signal input and microstrip line
18
is used for signal output.
When such an magnetostatic wave element
10
is used, a magnetic field H is applied, for example, in the direction parallel to the microstrip lines
16
and
18
. Accordingly, when a microwave signal is input at one of the microstrip lines such as microstrip line
16
, it is converted to a magnetostatic wave and the magnetostatic wave propagates through the single crystal magnetic garnet film
14
. Then it is converted to microwaves at the other microstrip line
18
and is output as a microwave output signal.
With such a magnetostatic wave element, when an input signal with an electric power Pin which is not less than Psh is input at a frequency f
o
, a signal with an electric power which is smaller than that of the input signal by the value of Pin-Psh is output only for the region of frequency f
o
as shown in
FIGS. 2A and 2B
. An S/N enhancer, a limiter, etc., may be manufactured utilizing this behavior.
Thus, this magnetostatic wave element provides an output signal with an electric power smaller than that of the input signal at frequency f
o
. There is also observed a phenomenon in which an output signal is suppressed for an input signal with an electric power smaller than Psh in a frequency region which is smaller or larger than f
o
. Although an output signal is preferably not suppressed for an input signal with an electric power not more than Psh in practice, there is such a phenomenon in reality, degrading the properties of a magnetostatic wave element.
In general, a magnetostatic wave element which has good properties has desirably a narrow bandwidth range in which an output signal is suppressed for an input signal with an electric power not more than Psh. That is, a magnetostatic wave element with a narrow bandwidth range Ba is preferable, when a bandwidth range in which an output signal is suppressed centering around frequency f
o
by 3 dB or more, is represented by Ba as shown in
FIGS. 2A and 2B
.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a magnetostatic wave element having a narrow bandwidth range Ba in which an output signal is suppressed centering around frequency f
o
by 3 dB or more for an input signal with an electric power not more than Psh, as well as to provide a manufacturing method therefor.
Various aspects of the present invention are described as follows.
(1) According to the present invention, a magnetostatic wave element comprising a single crystal magnetic garnet film is manufactured, wherein the film contains about 5 ppm or less by weight of Pb.
(2) In such a magnetostatic wave element, the single crystal magnetic garnet film can be formed on a non-magnetic substrate by the liquid phase epitaxial method.
(3) Furthermore, the single crystal magnetic garnet film can be formed by the liquid phase epitaxial method using a raw material comprising MoO
3
.
(4) Furthermore, the single crystal magnetic garnet film can be an yttrium-iron-garnet-based single crystal film.
(5) Furthermore, the single crystal magnetic garnet film can comprise two microstrip lines located on the film and approximately in parallel with each other with a specific distance therebetween.
(6) According to the present invention, such an element is manufactured by a method for manufacturing a magnetostatic wave element having a single crystal magnetic garnet film, comprising the steps of:
preparing a raw material by melting into a solvent having a molybdenum oxide as the principal component and being substantially Pb-free, a single crystal film forming component for forming the single crystal magnetic garnet film; and
bringing this raw material into contact with a seed substrate to grow a single crystal magnetic garnet film with a Pb content of about 5 ppm or less by weight on the seed substrate.
(7) According to the present invention, such an element is also manufactured by a method for manufacturing a magnetostatic wave element as set forth in the above-described (6), wherein the molybdenum oxide is MoO
3
.
(8) According to the present invention, such an element is also manufactured by a method for manufacturing a magnetostatic wave element as set forth in the above-described (6), wherein the solvent further comprises an alkali metal oxide.
(9) According to the present invention, such an element is also manufactured by a method for manufacturing a magnetostatic wave element as set forth in the above-described (8), wherein the solvent comprises about 50-90 mol % of the molybdenum oxide, and about 10-50 mol % of the alkali metal oxide.
(10) According to the present invention, such an element is also manufactured by a method for manufacturing a magnetostatic wave element as set forth in the above-described (6), wherein the single crystal film forming component is a component of an yttrium-iron-garnet system.
(11) According to the present invention, such an element is also manufactured by a method for manufacturing a magnetostatic wave element as set forth in the above-described (6), wherein the seed substrate is a non-magnetic substrate.
(12) According to the present invention, such an element is also manufactured by a method for manufacturing a magnetostatic wave element as set forth in the above-described (11), wherein the non-magnetic substrate is a substrate made of a gadolinium-gallium-garnet system.
(13) According to the present invention, such an element is also manufactured by a method for manufacturing a magnetostatic wave element as set forth in the above-described (6), wherein two microstrip lines are formed on the single crystal magnetic garnet film and approximately in parallel with each other at a specific distance therebetween.
A single crystal magnetic garnet film formed on a non-magnetic substrate by the liquid phase epitaxial method is mainly used for a magnetostatic wave element. To form a single crystal magnetic garnet film on a non-magnetic substrate, a solution of a single crystal film forming component melted as a solute in a solvent component is supersaturated, and the solution is brought into contact with a rotating non-magnetic substrate so as to grow a single crystal on the non-magnetic substrate. According to the most common methods, a Pb compound is used as one of the components for the solvent. Therefore, the single crystal magnetic garnet film thus manufactured comprises Pb which is not an element for constituting the magnetic garnet.
As a result of research to study the relationship between the content of Pb contained in a single crystal magnetic garnet film and the bandwidth range Ba in which an output signal was suppressed centering around frequency f
o
by 3 dB or more, it was found that Ba became narrower when there was a lower content of Pb, as shown in FIG.
3
. Thereupon, it was supposed that a magnetostatic wave element having good properties could be obtained if the single crystal magnetic garnet film was substantia
Fujino Masaru
Takagi Takashi
Chang Joseph
Dickstein Shapiro Morin & Oshinsky LLP.
Murata Manufacturing Co. Ltd.
Pascal Robert
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