JP2919031B2 - Magnetostatic wave S / N enhancer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION (Industrial application field) The present invention relates to an S / N enhancer using a magnetostatic wave device, and in particular, utilizes the fact that a magnetostatic wave filter has a frequency-selective nonlinear amplitude limiting characteristic. , Microwave propagation S /
The present invention relates to a magnetostatic wave S / N enhancer with improved N.

(Summary of the Invention) The present invention relates to an S / N enhancer using a magnetostatic wave device for improving a ratio (S / N) of a desired wave of microwaves and a disturbing wave (noise). By operating the magnetic wave filters at different input levels, utilizing the frequency-selective amplitude limiting effect of the magnetostatic wave filter, adjusting the two output levels at the output side and then synthesizing them in opposite phases, It is designed to improve the ratio between the high-level desired wave signal component and the low-level interfering wave (noise) component. Can now be obtained.

(Prior art) Conventionally, this type of S / N enhancer converts YIG (yttrium / gallium / garnet / garnet) formed on GGG (gadolinium gallium garnet) on a microstrip line or slot line to convert electromagnetic waves into magnetostatic waves. This was realized by a structure in which thin films were placed face to face. (References (1), (2)) FIG. 2 shows a typical structure example of this type of conventional S / N enhancer.

Microstrip line 13 input from input terminal 11
The electromagnetic wave propagating above is converted into a magnetostatic wave according to its level, and the magnetostatic wave propagates through the YIG thin film 14 and is absorbed by the absorber 18. Therefore, the energy of the electromagnetic wave at the output terminal 12 is attenuated by the amount converted to the magnetostatic wave. But the third
As shown, the amount to be converted into the magnetostatic wave is saturated when exceeding the threshold level where there is an electromagnetic wave level of the (third illustrated P _th), input-output characteristics of the magnetostatic wave filter is subjected to nonlinear amplitude limiting Therefore, the energy of the electromagnetic wave does not attenuate much, and the input energy appears at the output terminal 12 almost as it is. That is, due to this saturation phenomenon, the insertion loss is small for a high-level electromagnetic wave and conversely large for a low-level electromagnetic wave.

In addition, since the magnetostatic wave saturation phenomenon is frequency-selective,
By utilizing these properties, even when a plurality of signals are input at the same time, the insertion loss is determined according to each signal level, so that it can function as an S / N enhancer.

References (1) For example, JDAdam “Broadband Microwave Signal-
to-Noise Enhancer (Broadband microwave S / N enhancer), IEEE Trans. Vol. MAG-16, No. 5, pp. 1168-1170
(1980).

(2) JDAdam "A Slot-Line Magnetostatic Wave Signal-to-Nois
e Enhancer (slot line magnetostatic wave S / N enhancer), I
EEE Trans. Vol. MAG-21, No. 5, pp. 1794-1796 (1985).

(Problems to be solved by the invention) However, FIG. 5 shows a conventional S / N showing its input / output characteristics.
In the enhancer, the minimum input signal level (P _L ) at which the S / N improvement starts is -6 dBm, and the maximum improvement level, that is, the input level (P _H ) required to saturate the improvement level is +15 dBm. The input / output characteristics were slowly changing. As a result, there is a defect that a sufficient improvement effect cannot be obtained especially for a signal having a poor S / N.

The horizontal axis in FIG. 5 shows the input level in dBm, and the vertical axis shows the relative output level (dB). The linear input / output characteristic 24 is, for example, a magnetostatic wave conversion function on the microstrip line shown in FIG. The input / output characteristics of this device when the device is not provided, and the curve input / output characteristics 25 show the input / output characteristics of the device when the device is provided with a magnetostatic wave conversion function.

Therefore, an object of the present invention is to solve the above-described drawbacks of the conventional example,
In particular level P _H level significantly reduce the, by reducing the level difference between the level P _L and level P _H, is realized rapidly changing input and output characteristics, its also for S / N bad input signal It is an object of the present invention to provide a magnetostatic wave S / N enhancer capable of sufficiently improving the S / N.

(Means for Solving the Problems) In order to achieve this object, the magnetostatic wave S / N enhancer according to the present invention exhibits a linear input / output characteristic that is not subject to amplitude limitation for a low-level high-frequency input signal, A magnetostatic wave S / N enhancer using a magnetostatic wave filter having a frequency-selective and non-linear input / output characteristic exhibiting a saturation input / output characteristic subjected to an amplitude limitation for a high-level high-frequency input signal, the enhancer includes: Distribution means for distributing a high-frequency input signal into the high-level high-frequency input signal and the low-level high-frequency input signal; a first magnetostatic wave filter that receives the high-level high-frequency input signal as input; A second magnetostatic wave filter having a high-frequency input signal as input and having substantially the same input / output characteristics as the first magnetostatic wave filter; a noise component output of the first magnetostatic wave filter and a second magnetostatic wave A synthesizing means for synthesizing the high-frequency outputs of the first magnetostatic wave filter and the second magnetostatic wave filter such that the noise component output of the filter has the same amplitude and opposite phase and cancel each other. It is.

(Embodiment) The gist of the present invention is that two dual magnetostatic wave filters having the same characteristics are used, and one filter is set at a level such that the amplitude is restricted, and the other filter is not subjected to the amplitude restriction. (Input / output characteristics are linear range) level,
For two low-level signals such as noise, the two filter outputs below the level that perform linear operation are subjected to equal-amplitude and opposite-phase synthesis to eliminate signal components such as low-level noise. .

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a structural block diagram of an embodiment of an S / N enhancer using two magnetostatic wave films according to the present invention. Here, the dual refers to a filter in which two magnetostatic wave filters are formed on, for example, the same substrate and undergoes the same change in physical properties with respect to disturbance. This is a filter that once converts into a magnetostatic wave according to the output characteristics, and then converts again into a microwave in a linear relationship.

The microwave signal input from the input terminal 1 is distributed to different power ratios by the directional coupler 5 or the combination of the power distributor and the attenuator. The low level signal is input to the magnetostatic wave filter. In this case, the input level of the filter 4 is within the level range where the input / output characteristics are always linear, that is, the input level P in the input / output characteristics of the magnetostatic wave filter shown in FIG.
It is set to the level below _th .

Further, for a low-level input signal within a range in which the two filters 3 and 4 perform linear operation, the output signal passing through both filters is attenuated by the directional coupler 6 so as to be synthesized with equal amplitude and opposite phase. In the case of the magnetostatic wave S / N enhancer of the present invention, since the delay device 7 and the delay line 8 (or a phase shifter are also possible) are adjusted, in such a case, they are eliminated in the directional coupler 6 and the low level to the enhancer is reduced. The input signal of the level is output terminal 2 of the enhancer.
Only a very low level signal appears.

However, the high-level input signal to the enhancer, the input signal having the level _Pth or more in the third illustrated input / output characteristic, the amplitude of the output signal is limited by the saturation characteristic of the filter 3, and the directional coupler 6 has equal amplitude and opposite phase. And the signal passed through the filter 4 appears at the output terminal 2 almost as it is. That is, the embodiment according to the present invention has a function as an S / N enhancer in which the lower the level of the input signal, the larger the insertion loss, and the higher the level, the smaller the insertion loss.

FIG. 4 shows a measurement example of the input / output characteristics of the S / N enhancer according to the present invention obtained by setting the degree of coupling of the directional coupler 6 to -30 dB. 4th linear input / output characteristic 22 and curve input / output characteristic 23
Have the same relationship as those shown in FIG.

Now, comparing the characteristics of FIG. 4 and FIG.
In the S / N enhancer, the level P _L (−6
dBm) and the level P _H (+15 dBm) because the level difference (21 dB) is large, the input / output characteristics change slowly during this period, whereas the level P _{L in the} S / N enhancer according to the present invention.
(-20 dBm) and the level P level difference between _H (-14dBm) (6d
Since B) is small, this output is an extremely steep change in input / output characteristics.

This means, for example, that the ratio between the desired signal and the interference signal (noise) is 2
In the case of 33 dB, the improvement of about 5 dB is the limit in the conventional type, but the improvement according to the present invention can be improved by 15 dB or more, and there is still room for improvement in principle. Also relate to the present invention we compare the absolute level value of the level P _L and level P _H, 15 dB approximately at the level P _L, 30 dB at the level P _H
This has the advantage that the operating input signal level can be reduced by 15 dB or more compared with the conventional type.

Although only a part of the embodiment according to the present invention has been described above, it is obvious to those skilled in the art that the present invention is not limited to this and various modifications and changes are possible within the scope of the claims. There will be.

(Effects of the Invention) As described above in detail, according to the magnetostatic wave S / N enhancer of the present invention, the degree of improvement in S / N is greatly increased as compared with the conventional example, and the operation input signal level is also considerably reduced. This has the advantage of being able to

Furthermore, since the enhancer of the present invention is constituted by a dual magnetostatic wave filter, even if a change in the characteristics of the YIG itself or a change in the external DC magnetic field occurs, it has the advantage that the effect on the characteristics of the entire circuit is extremely small. ing.

[Brief description of the drawings]

FIG. 1 shows a configuration of an embodiment of an S / N enhancer using dual magnetostatic wave filters according to the present invention. FIG. 2 shows a typical example of a conventional S / N enhancer. FIG. 3 shows the input / output characteristics of the magnetostatic wave filter, and FIGS. 4 and 5 show the input / output characteristics of the present invention and the conventional S / N enhancer, respectively. 1 ... input terminal, 2 ... output terminal 3,4 ... magnetostatic wave filter, 5,6 ... directional coupler 7 ... attenuator, 8 ... delay line 11 ... input terminal, 12 ... output Terminal 13: Microstrip line 14: YIG thin film, 15: GGG substrate 16: Conductor plate, 17: Dielectric substrate 18: Magnetostatic wave absorber

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01P 1/23 H01P 1/215 H01P 9/00 H04B 1/10 JOIS WPI / L

Claims (1)

(57) [Claims] 1. A frequency selection circuit which exhibits a linear input / output characteristic which is not subjected to amplitude limitation for a low-level high-frequency input signal and a saturated input / output characteristic which is subjected to amplitude limitation for a high-level high-frequency input signal A magnetostatic wave S / N enhancer using a magnetostatic wave filter having a characteristic and non-linear input / output characteristic, the enhancer distributes a high-frequency input signal to the high-level high-frequency input signal and the low-level high-frequency input signal. A first magnetostatic wave filter for inputting the high-level high-frequency input signal; and an input for receiving the low-level high-frequency input signal;
A second magnetostatic wave filter having substantially the same input / output characteristics as the first magnetostatic wave filter; and a noise component output of the first magnetostatic wave filter and a noise component output of the second magnetostatic wave filter having the same amplitude and opposite. Synthesizing means for synthesizing the high-frequency outputs of the first magnetostatic wave filter and the second magnetostatic wave filter so as to cancel each other out of phase.
S / N enhancer.