JPH039384Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a filter bank consisting of a plurality of filters provided in a receiving section of a radar or the like.

Conventional filter banks of this type, for example,
As shown in the figure, a signal received by an antenna 1 is mixed with a signal from a local oscillator 3 via a mixer 2, and converted into an IF signal.
It was configured to pass through a plurality of surface acoustic wave filters 4.

That is, in the conventional filter bank of this kind, since the upper limit of the frequency band of the surface acoustic wave filter 4 is 1 to 2 GHz, it is necessary to convert the signal received by the antenna 1 into an IF signal and process it. Therefore, a local oscillator 3, a mixer 2, etc. are required, resulting in a large number of parts and a complicated configuration.

This device includes a magnetostatic wave excitation strip 6 on a magnetostatic wave propagation medium 5, and a plurality of strips that reflect the magnetostatic wave excited by the excitation strip 6 in a direction different from the magnetostatic wave propagation direction. A reflector 7 and a plurality of receiving strips 8 for receiving the magnetostatic waves reflected by the reflector 7 are provided, and a DC magnetic field is applied in a direction perpendicular to the surface of the magnetostatic wave propagation medium 5 to form a filter bank. By constructing the
A detailed explanation will be given below using an example shown in FIG.

FIG. 2 shows an example of a filter bank according to this invention, and 5 shows YIG (yttrium, ion ion) formed on GGG (gadolinium, gallium, garnet) using liquid phase epitaxial growth technology. It is a magnetostatic wave propagation medium such as a thin film (garnet). 6 is a strip for magnetostatic wave excitation formed on the magnetostatic wave propagation medium 5.
Although the excitation strip 6 is shown with an open end, it may be short-circuited.

Now, YIG forming the magnetostatic wave propagation medium 5 mentioned above.
If a bias magnetic field is applied to the thin film in the perpendicular direction as shown by the arrow in the figure, the strip 6
MSFVW (Magneto Static Forward)
A magnetostatic wave in a mode called volume wave is excited and propagates in a direction perpendicular to the excitation strip 6. 7 is a reflector that reflects the magnetostatic wave excited by the excitation strip 6 in a direction different from the propagation direction. The reflector 7 is
It consists of a plurality of metal linear arrays provided on the magnetostatic wave propagation medium 5, or a plurality of linear groove arrays formed on the surface of the magnetostatic wave propagation medium 5 by ion beam processing, etc. . Reference numeral 8 denotes a receiving strip for receiving the magnetostatic waves reflected by the reflector 7, and although the strip is shown with an open end, it may also be short-circuited at the end.

Now, a plurality of the reflectors 7 are provided on the magnetostatic wave propagation medium 5, but the pitch of the linear array constituting the reflectors 7 can be made different for each reflector 7. For example, each reflector 7 can reflect static magnetic waves in different frequency bands. Therefore, the plural receiving strips 8 provided corresponding to the reflectors 7 receive magnetostatic waves of different frequency bands.
That is, a filter bank can be formed with the above configuration.

By the way, since the filter bank according to this invention is constructed using static magnetic waves as described above,
It can operate at frequencies in the 1-20 GHz band. Therefore, in the filter bank according to this invention, there is no need to convert the received signal from the antenna 1 into an IF signal as in the conventional case. Therefore, there is an advantage that the configuration is simpler than the conventional one.

Furthermore, in this invention, as shown in FIG. 2, a DC magnetic field is applied perpendicularly to the surface of the YIG thin film. This produces the effects described below. If a DC magnetic field is applied in the direction along the surface of the YIG thin film, the propagation characteristics of the magnetostatic wave depend on the propagation direction. Therefore, mode conversion will occur due to the reflector 7. For this reason, for example, if a magnetostatic wave propagating along the surface of the YIG thin film is converted into a magnetostatic wave propagating along the back side of the YIG thin film, and it becomes impossible to receive it with the receiving strip provided on the surface, This causes problems such as a reduction in reflection efficiency due to mode conversion. In contrast, in the embodiment shown in FIG. 2, a DC magnetic field is applied perpendicularly to the surface of the YIG thin film. As a result, the propagation characteristics of the magnetostatic wave become uniform within the plane regardless of the propagation direction. Therefore, the reflector 7 acts only to convert the magnetostatic wave in the propagation direction, and no mode conversion occurs between the magnetostatic wave incident on the reflector 7 and the magnetostatic wave reflected by the reflector 7. Therefore, the structure in which the magnetostatic wave excitation strip 6 and the receiving strip 8 are both provided on the same surface of the YIG thin film has the advantage that the level of the magnetostatic wave signal received by the receiving strip can be increased. in this way,
The configuration in which both the excitation strip and the reception strip are provided on the same surface of the YIG thin film has the advantage that both can be fabricated with only one etching process. Furthermore, since the configuration does not involve mode conversion, there is an effect that the reflection efficiency of the reflector 7 can be increased.

Furthermore, in the filter bank according to this invention, the frequency of the precession of electron spins can be changed by changing the magnitude of the DC magnetic field, so the frequency of the signal received by each receiving strip 8 can be varied. It is possible. In other words, there is also the effect of obtaining a tunable filter bank.

Although the above description has been made regarding the embodiment shown in FIG. 2, the present invention is not limited to this, and the excitation strip 6 and reception strip 8 may be loop-shaped or meander line-shaped. , a grating shape, etc. may be used.

As described above, in the filter bank according to this invention, a DC magnetic field is applied to the magnetostatic wave propagation medium in a direction perpendicular to the surface of the propagation medium, and
A magnetostatic wave excitation strip is disposed on the propagation medium, a plurality of reflectors that reflect the magnetostatic wave excited by the excitation strip in a direction different from the propagation direction of the magnetostatic wave, and the reflector Since the filter bank is configured with multiple receiving strips that receive the static magnetic waves reflected by the filter, it can operate up to high frequencies, and equipment such as mixers and local oscillators is not required, making the configuration simple. This has the advantage that mode conversion due to change in the propagation direction of the magnetostatic wave does not occur, and the level of the magnetostatic wave signal received by the receiving strip can be increased.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a conventional filter bank, and FIG. 2 is a diagram showing an embodiment of the filter bank according to this invention. In the figure, 1 is an antenna, 2 is a mixer, 3 is a local oscillator, 4 is a surface acoustic wave filter, 5 is a magnetostatic wave propagation medium, 6 is an excitation strip, 7 is a reflector, and 8
is the receiving strip. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

Claims (1)

[Scope of utility model registration request] A DC magnetic field is applied to the magnetostatic wave propagation medium in a direction perpendicular to the surface of the propagation medium, and magnetostatic wave excitation strips are formed on the propagation medium in a linear array, each having a different pitch. , a plurality of reflectors arranged obliquely with respect to the propagation direction of the magnetostatic waves excited by the excitation strip, and reflecting the magnetostatic waves in a direction different from the propagation direction of the magnetostatic waves; and the reflectors. 1. A filter bank comprising a plurality of receiving strips for receiving static magnetic waves reflected by a filter bank.