JPS62271501A - Magnetostatic wave nonlinear device - Google Patents

Abstract

PURPOSE:To attain broad band by decreaseing the magnetic field strength distribution applied to a YIG thin film device stepwise so as to specify the propagation direction of an electromagnetic wave. CONSTITUTION:A magnetic field having different uniformed strength distribution is fed to a YIG thin film 2 of a microstrip line 6 by a permanent magnet 12 having a large magnetic pole area, a permanent magnet 11 having a small magnetic pole area and a magnetic adjuster iron piece 13 so as to propagate an electromagnetic wave thereby reducing the magnetic field strength distribution stepwise from the strong magnetic field part of the strip conductor 5 toward the weak magnetic field part. Then the noise is attenuated more than the high frequency signal in the strong magnetic field part and both attenuations are less in the weak magnetic field part, the S/N is improved totally to attain broad band of a magnetostatic wave nonlinear device.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Field of Industrial Application] This invention relates to a microwave signal processing device using static magnetic waves.

[Prior art J II 9 diagrams are shown in, for example, Appl, Phya, Lat
t, 36 (6ha 15March 1980.pp
, 485-487 is a perspective view showing the magnetostatic wave nonlinear device shown in FIG. In the figure, (1) is a GGG (Gadolinic Mugalic Mugarnet) substrate, and (2) is a G
GG substrate (1) is a YIG (yttrium iron-garnet) thin film fabricated by liquid phase growth on the surface, (3) is a YIG
#! 1 (2) Absorber attached to both ends of the surface, (4)
Dielectric substrate with ground conductor closely attached to the back side of Fi, (5) is YI
G thin 111 (23 strip conductor close to the surface, (6
) tj microstrip line composed of the above dielectric substrate (4) and the above strip conductor, (η is the metal base, (8) is the permanent magnet, (9) is the a-blow, (lO) is the above permanent magnet (8) and the above-mentioned yoke (9).

Next, the operation will be explained. Here, YIG thin [(2
), the length direction of the strip conductor (5) is in the direction, and the surface of the YIG thin film (2) is! There will be 7 sides. This YIG#
A magnetic field HO uniform in the X direction is applied to N(2) by the magnetic circuit (10). This magnetic field Ho is a YIG thin film (2
) plane, and the ratio of the thickness of the YIG thin film (2) to the length in the Hil is equal to the applied magnetic field HO.

First, when a small power harmonic wave corresponding to noise etc. is incident on the microstrip mm(6), the frequency range f
YI close to the strip conductor (5) at il~fb1
A magnetostatic surface wave is excited in the G thin Ps(2) in proportion to the power of the electromagnetic wave. Here, fll<fhl, and YI
If the saturation magnetization of the G thin film (2) is 4πM8 and the gyromagnetic ratio is T, fll is T /H11 (H1t+4rMa),
fhl is expressed as T(H1l+2πMa). Due to the excitation of this magnetostatic surface wave, the power lost when a small power electromagnetic wave passes through the microstrip line (6) is proportional to the power of this electromagnetic wave and is equal to the power converted into a magnetostatic surface wave. When an electromagnetic wave with a large power equivalent to a signal etc. enters the microstrip line (6), if the electric power exceeds a certain power value pth and the wave number of the electromagnetic wave exceeds 2TH11, the electron spin aging, which is unique to magnetic materials such as YIG, will occur. A non-41 type effect of differential motion occurs, and the amount of magnetostatic surface waves excited is not proportional to the power of the electromagnetic wave, but saturates and becomes a constant value. Furthermore, when the above-mentioned nonlinear effect occurs, a wave called an f/2 spin wave is simultaneously excited, and this wave immediately after the excitation
! It is converted to lIK.

For this reason, the power lost when electromagnetic waves with large power greater than pth passes through the microstrip line (6) is:
The electric power converted to the magnetostatic surface plate by a certain value due to saturation,
It is equal to the sum of the powers converted into f/2 spin waves.

Therefore, when comparing the insertion loss determined by the ratio of the power lost when passing through the microstrip line (6) and the incident power in two cases, one in which a small power Ota technique and one in which a large electromagnetic wave of PTH or more is incident, it is generally found that Pth
The intrusion loss is smaller when a larger electric ini is incident than the above. Therefore, nonlinearity appears in that as the power of the incident electromagnetic wave increases, the intrusion loss of the microstrip line (6) decreases.

Conventional magnetostatic wave nonlinear devices utilize this property, and the noise of a small incident power is greatly attenuated.
Since high power signals are attenuated slightly, it has the function of expanding the signal-to-noise ratio.

[Problem that the invention seeks to solve]

Since the conventional magnetostatic wave nonlinear device makes the internal magnetic field in the YIGN expansion (2) uniform as described above, it is limited between the 11J working band JiiE width h T Hls (H1x + 4gM5) and 11' ()Iil + 2 + cMa). There was a problem that

This invention was made to solve the above-mentioned problems, and its purpose is to obtain a magnetostatic wave nonlinear device that can achieve a wide band.

Means for Solving Problem c] In the magnetostatic wave nonlinear device according to the present invention, %YI
In the G thin film, the intensity distribution of the magnetic field is gradually decreased in a stepwise manner in the direction along the microstrip conductor, from the strip conductor close to the YIG thin film to which a strong magnetic field is applied to the strip conductor close to the YIG thin film to which a weak magnetic field is applied. It is designed to propagate electromagnetic waves in the direction of the strip conductor.

[Effect]

In the magnetostatic wave nonlinear device of this invention, the frequency band width in which magnetostatic surface waves are excited is expanded by applying a step-like nonuniform magnetic field to the YIG thin film and specifying the propagation direction of electromagnetic waves. Moreover, deterioration of the reliability-to-noise ratio due to f/2 spin technique excitation caused by making the magnetic field non-uniform is suppressed, and a wide band can be realized.

[Embodiment 1] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1st
In the figure, (11) #-j permanent magnet with a small magnetic pole area, (12) H permanent magnet with a large magnetic pole area, (13) a magnetic shunt iron piece attached to the permanent magnet (11) with a small magnetic pole area, (14) ) are these permanent magnets (11), (12)
, a magnetic 9L circuit consisting of a magnetizing iron piece (13) and a yoke (9), (15) is an input terminal, and (16) is an output terminal.

Next, the operation will be explained. Here, in order to simplify the explanation, a case will be described in which the magnetic field strength distribution that sequentially decreases in a stepwise manner has a stepwise binary strength distribution. FIG. 2 shows the magnetic field strength distribution between the magnetic shunt iron piece (13) and the permanent magnet (12) with a large magnetic pole area. Since the two magnetic pole shapes of the magnetic circuit (14) are different, the magnetic field strength distribution is non-uniform. In addition, permanent magnets with a small magnetic pole area (1
For example, by making the tip of the magnetic shunt iron piece (13) attached to the magnetic field shunt iron piece (13) concave as shown in Fig. 1, the magnetic field strength distribution near this magnetic shunt iron piece (13) can be flattened. can. Inside the YIG thin film (2) placed in this magnetic field,
As mentioned above, the influence of the demagnetizing field is negligible, and there is an internal magnetic field equal to the strength of this magnetic field. Here, in order to simplify the following explanation, the intensity distribution of the internal magnetic field is approximated to a step-like distribution as shown in FIG. Further, the weaker one of these binary internal magnetic field strengths is designated as Hl2, and the stronger one is designated as Him. Furthermore, the internal magnetic field intensities Hi2 and Hlm are the respective internal magnetic field intensities Hi! , Hlm The operation band v of the silent magnetic wave flat linear device is determined so that fhl and flll of f12 to fh2 and flll to fh3 match. fffi
D fll, fhl, fls, fbs o large tJJl
Let fll<fhll=fll<fhl. FIG. 4 shows the relationship between the internal magnetic field strength and the operating band. Note that the shaded area in the figure indicates the operable chain plate of the magnetostatic wave nonlinear device. 5 and 6 show the insertion loss characteristics of a magnetostatic wave nonlinear device to which internal magnetic field strengths of Hlm and 1lil are applied independently, respectively. The magnetostatic wave nonlinear device according to the present invention can be regarded as a series connection of two magnetostatic wave nonlinear devices having the intrusion loss characteristics shown in FIGS. 5 and 6. However, in order to increase the signal-to-noise ratio in the fll - fhl frequency range, a weak magnetic field is applied from the strip conductor (5) close to the YIG thin film (2) to which a strong magnetic field is applied.
It is necessary to propagate electromagnetic waves in the direction of the strip conductor (5) close to G 4M (2). The reason for this will be explained below. In the following description, the YlG thin [(2)% microstrip line (6) to which the weak magnetic field H12 and the strong magnetic field H1s are applied will be referred to as the weak magnetic field section and the strong magnetic field section, respectively.

First, power loss due to f/2 spin waves outside the band where magnetostatic surface waves are excited will be explained. At frequencies higher than the band in which magnetostatic surface waves are excited, only the power loss converted to r/2 spin waves occurs in the microstrip line (6).
This contributes to the intrusion loss. However, the intrusion loss in this case increases as the power of the electromagnetic wave increases, and the signal-to-noise ratio decreases.

On the other hand, the frequency T v' Hl (H1
+4πMs) are almost the same in the normally used frequency band, so the influence of power loss due to f/2 spin waves does not appear at frequencies lower than the band in which magnetostatic surface waves are excited.

Therefore, the lower side f12 to f of the frequency band fll to fhll
In h2, the intrusion loss in the strong magnetic field part //i is almost 0 as shown in Figure 6, so the overall intrusion loss characteristic when the strong magnetic field part and the weak magnetic field part are connected in series is Even if electromagnetic waves are incident from the part where the magnetic field is applied, the insertion loss characteristics match the insertion loss characteristics of the weak magnetic field part. Therefore, since the effect of increasing the signal-to-noise ratio appears, there is no interval M.゛On the other hand, the high frequency side fil~f of the frequency band fllll~fhl
In h3, the weak magnetic field part has a signal-to-noise (Q
) acts to reduce the ratio. For this reason, the high frequency side f1m-
” In fhl, the effect of reducing the signal-to-noise ratio in the weak magnetic field portion and the effect of increasing the signal-to-noise ratio in the strong magnetic field portion are superimposed.In this frequency band, according to the configuration of the present invention, When the electric Wi wave is propagated in the direction of the weak magnetic field part, the effect of increasing the signal-to-noise ratio first occurs in the strong magnetic field part, and the signal is slightly attenuated and the noise is greatly attenuated.

Therefore, the power of the signal that enters the next weak magnetic field section is considerably smaller, and this signal and noise are hardly attenuated in the weak magnetic field section. Therefore, when an electromagnetic wave is propagated from a strong magnetic field part to a weak magnetic field part, the total intrusion loss of the strong magnetic field part and the weak magnetic field part is larger for noise than for the signal, and the signal-to-noise ratio is This has the effect of increasing the size. FIG. 7 shows the insertion loss characteristics of the magnetostatic wave nonlinear device according to the present invention that propagates electromagnetic waves from a strong magnetic field section to a weak magnetic field section. At frequencies flJ to fbj, the intrusion loss for faith becomes larger than the intrusion loss for noise, and the frequency f
The signal-to-noise ratio can be increased in l to fhs.

However, as above, the high plate side frequency band w, f11 to f
In ba, when electromagnetic waves propagate from the weak magnetic field part to the strong magnetic field part, contrary to the configuration of the present invention, the effect of reducing the signal-to-noise ratio is first exerted in the weak magnetic field part, and the signal is greatly attenuated. However, the noise is not attenuated. Therefore, the power of the signal incident on the next strong magnetic field section is reduced, and the signal g in the strong magnetic field section is greatly attenuated along with noise. Therefore, when electromagnetic waves are propagated from a weak magnetic field part to a strong magnetic field part, the total intrusion loss of the weak magnetic field part and the strong magnetic field part is
The effect of increasing both signal and noise and increasing the signal-to-noise ratio does not appear. FIG. 188 shows insertion loss characteristics in a case where electromagnetic waves are propagated from a weak magnetic field part to a strong magnetic field part, contrary to the configuration of the present invention. Frequency fl~fh
At 1, the insertion loss for the signal is on the same level as the noise, and the signal-to-noise ratio cannot be increased in this frequency band.

As described above, by applying a non-uniform magnetic field to YIG thin Al(2) and propagating electromagnetic waves from the strong magnetic field part to the weak magnetic field part, we can expand the frequency at which magnetostatic surface waves can be excited and increase the magnetic field. This has the effect of suppressing deterioration of the signal-to-noise ratio due to non-uniformity and achieving a wider band.

In addition, in the practical example above, the case of a step-like magnetic field strength distribution with almost two strong and weak values was explained, but it is also possible to
Even if the value exceeds this value, the same effect can be achieved as long as the electromagnetic waves are incident from the part to which a strong magnetic field is applied.

Effects of the Invention J As described above, according to the present invention, YIG thin-rolled (2) This has the effect of increasing the

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a magnetostatic wave nonlinear device according to an embodiment of the present invention, FIG. 2 is a magnetic field strength distribution diagram between magnetic poles of the magnetostatic wave nonlinear device according to the present invention, and FIG. 3 is a magnetic field shown in FIG. Modeling the intensity distribution12) Figures 9 and 4 are diagrams showing the relationship between the YIG thin film internal magnetic field strength and the operating band of the magnetostatic wave nonlinear device, Figure 5 is the insertion loss characteristic of the weak magnetic field portion, and Figure 6 7 is an insertion loss characteristic diagram of the strong magnetic field section, FIG. 7 is an intrusion loss characteristic diagram of the magnetostatic wave nonlinear device according to the present invention, and FIG. 8 is an insertion loss characteristic diagram when electromagnetic waves are propagated from a weak magnetic field section to a strong magnetic field section. , Figure 9 is
FIG. 2 is a perspective view showing a conventional magnetostatic wave nonlinear device. (2) is a Y-all membrane, (3) is an absorber,
(4) is a dielectric substrate, (5) is a strip conductor, (6)
is a microstrip line, and (14) is a magnetic circuit. In addition, in FIG. 1, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] A part of the electromagnetic waves propagating through a microstrip line having a strip conductor is nonlinearly converted into a static magnetic wave inside a YIG thin film placed near the strip conductor and subjected to a magnetic field in the length direction of the strip conductor. The above YIG
The intensity distribution of the magnetic field applied to the thin film is made to be a distribution that gradually decreases in an almost step-like manner in the length direction of the strip conductor, from YIG thin film to which a strong magnetic field is applied to YIG thin film to which a weak magnetic field is applied.
A magnetostatic wave nonlinear device characterized by having a configuration in which electromagnetic waves in a microstrip line are propagated in the direction of a thin film.