JPS62224101A - Magnetostatic wave filter bank - Google Patents

Abstract

PURPOSE:To obtain a mangetostatic wave filter bank operated at a minimized magnetic field by providing a magnetic circuit impressing a DC magnetic field perpendicular in the lengthwise direction of the strip of a strip shaped YIG thin film waveguide path and in parallel with the thin film face. CONSTITUTION:The magnetic field circuit 22 is constituted between permanent magnet plates 19 and 20 so as to apply the DC magnetic field perpendicular in the direction of the strip of the 1st-3rd strip YIG thin film conductor guide paths 1-3 and in parallel with the thin film face. Since the area of opposed magnetic poles of the two permanent magnet plates 19, 20 differs from each other, the DC magnetic field of the gap is ununiformized. Since the direction of the impressed DC magnetic field is within the YIG thin film face and the thickness of the strip YIG thin film is several tens of microns, which is mush smaller than the width and length, the effect of the anti-magnetic field is neglected and the strength of the DC magnetic field in the operation at a required frequency band is very small.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a microwave signal processing device using magnetostatic waves.

[Conventional technology]

Figure 2 shows, for example, engineering E E M T T -S D
igest(J, D, Adam, ” An E
pitaxial YIG 1O-Channel E
'1lter Bank'', 1982. p 78
79) is a perspective view showing the schematic structure of the conventional magnetostatic filter puncture shown in (1) to (3).
) are the first to third strip-shaped YIG (yttricum-scissor-garnet) thin film waveguides grown in liquid phase on a gadolinium-gallium-garnet substrate;
The input side transducers (6) to (8) are composed of microstrip lines having the function of 5) and intersect with one end of the first to third YIG thin film waveguides (1) to (3). These are first to third output side transducers configured by microstrip lines having tips (9) to (11). These first to third output side transducers (6) to (8) are connected to the first to third YIG thin film waveguides (
They are arranged so as to intersect with the other ends of 1) to (3), respectively. In addition, (12) is the input/output side transducer (
4), coaxial terminal connected to (6) to (8), (13)
is a dielectric substrate forming a microstripe line, (1
4) is the housing, (15) and (16) are the magnetic plates, (17)
Haat iron, (18) ID magnet plate (15), (16)
and a magnetic circuit consisting of a yoke (17).

Next, the operation will be explained. Due to the magnetic circuit (18) having a non-uniform magnetic field in the gap, the first to third strip-shaped YIG thin film waveguides (1) to (3) K have different directions in the direction perpendicular to the plane of these thin films. Magnetic field H1, Hl, H3
is applied.

For this reason, the first to third Y-type awi, film waveguides (1) to (
3), magnetostatic forward volume waves (
MSE'VW) propagates. The lower limit frequencies of the propagation band are T(Hl-N・4πM) and T(Hl-N
・4πM) IT (H3-N -4ycyr),
(Ht-1-(1-N)・4πM), T (Hl-
N・4πM) (H2+(1-N)・plane, T(H3
−N・4πM)(H3+(1−N)・4πM) Here, T is the gyromagnetic ratio, N is the demagnetizing field coefficient, 4π
M is the saturation magnetization of YIG. This band is usually IGH
z or more, and in order to use it as a filter puncture, it is necessary to make the pass band only a narrow frequency band near the lower limit frequency where the propagation loss of the magnetostatic forward volume wave is small. 6) The shapes of (7) and (8) have been adjusted.

Therefore, input side transducer (4) K constant OR
When the F constant power is input through the coaxial terminal (12) and the number of revolutions is swept, each output side transducer (6) to (8) has an RF constant of different revolutions in several bands, as shown in Figure 3. Power appears. Therefore, the input transducer (
When an RF signal of an unknown frequency is added to 4), the frequency band can be determined by which output transducer the RF constant power appears in. Further frequency bandwidth,
And increasing the resolution can be achieved by increasing the YIG thin film waveguide and adjusting the magnetic field strength, as well as adjusting the frequency response of the output transducer.

[Problem that the invention seeks to solve]

The conventional magnetostatic wave filter puncture is configured as described above, and in order to operate in the required frequency band, the demagnetizing field N.
It requires a large magnetic field that overcomes 4πM, and has the disadvantage that the permanent magnet used in the magnetic circuit must be an expensive one such as a rare earth magnet.

This invention was made to solve the above-mentioned problems, and aims to obtain a magnetostatic wave filter puncture that operates with as small a magnetic field as possible.

[Means for solving problems]

The magnetostatic wave filter puncture according to the present invention is perpendicular to the length direction of the strip of the strip-shaped YIG thin film special wave path,
The magnetostatic surface i (
Mssw) is used.

[Operation J] By using the magnetostatic wave filter puncture and the magnetostatic surface wave in this output 11c, the influence of the demagnetizing field in the YIG thin film is eliminated, and a magnetic circuit having a small DC magnetic field is constructed.

〔Example〕

An example of this origin will be described below with reference to the drawings. In Fig. 1, (19) and (20) are permanent magnet plates whose opposing magnetic poles have different areas, and (21) is a permanent magnet plate (
19) This is a yoke that together with (20) constitutes the magnetic circuit (22).

In the magnetostatic wave filter puncture according to the embodiment of the present invention, between the permanent magnet plates (19) and (20), the first to
Third strip-shaped YIG thin film waveguide (1) to (3)
A magnetic circuit (22) is configured to apply a direct current magnetic field perpendicular to the length of the strip and parallel to the thin film.

Further, since the areas of the opposing magnetic poles of the two permanent magnet plates (19) and (20) are different, the DC magnetic field in the gap becomes non-uniform. Assuming that the DC magnetic fields at the positions of the first to third YIG thin films (1) to (3) are respectively [1, [2, l(3)], the left permanent magnet plate (20) is compared to the right permanent magnet plate (20) in Fig. 1. Since the area of the permanent magnet plate (19) is increased, the magnetic flux density in the gap is smaller on the left side, and the relationship is Hl)Hl)H3.

With this configuration, the direction of the applied DC magnetic field is within the plane of the YIG thin film, and the thickness of the strip-shaped YIG thin film is several 10
The influence of the demagnetizing field can be ignored because it is very small compared to the width and length of microns. Each YIG thin film (1) to (3) has a lower limit frequency of T2H1+4πM), TZiii
A magnetostatic surface wave expressed as τi, r/1×17iη becomes possible to propagate. For example, 4πM of YIG is 1760 Gauss, and the lower limit direction it is 3.2. 3.0, 2.8
If you choose GHz, the applied DC magnetic field should be 550. 5
00. It should be 450 oersted. When using a conventional magnetostatic advancing body bond wave, the demagnetizing field coefficient N is about 0.5, and the applied DC magnetic field is 2020.1950.1800.
Since this is Oersted, the embodiment of the present invention can operate with about a quarter of the conventional applied DC magnetic field.

[Effect of the invention J As described above, since the magnetostatic wave filter bank according to the present invention uses magnetostatic surface waves, the strength of the DC magnetic field to operate in the required frequency band is small, and the magnetic circuit can be made at low cost. There is an effect that can be done.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing a magnetostatic filter bank according to an embodiment of the present invention, Fig. 2 is a perspective view showing a conventional magnetostatic filter bank, and Fig. 3 explains the operation of the conventional magnetostatic filter bank. Illustration for. (1) to (3) are the 1st to 30th YIG thin film waveguides, (4
) is the input side transducer, (6] to (8) are the first to
3 is the output side transducer, and (22) is the magnetic circuit. In addition, in the figure, the same symbol -8 indicates the same or equivalent part.

Claims (1)

[Claims] An input consisting of a plurality of YIG thin film waveguides having a strip shape through which magnetostatic waves can propagate, and one microstrip line arranged to intersect one end of all of the plurality of YIG thin film waveguides. side transducer;
An output side transducer, which is arranged to intersect with the other end of each of the plurality of YIG thin film waveguides, and is composed of the same number of microstrip lines as the plurality of YIG thin film waveguides; In a magnetostatic wave filter bank composed of magnetic circuits that apply different DC magnetic fields, a DC magnetic field perpendicular to the length direction of the YIG thin film waveguide and parallel to the thin film is applied, and a plurality of YIG thin film waveguides are What is claimed is: 1. A magnetostatic wave filter bank comprising: magnetic circuits having opposite magnetic poles having different shapes so as to apply different direct current magnetic fields to each magnetic circuit, and utilizing magnetostatic surface waves generated by the direct current magnetic fields.