SU1734047A1 - Method of analysis of spectrum of radio signal - Google Patents

Abstract

Use: The invention relates to radio engineering and electronics and can be used in the construction of optical and radio information processing systems, mainly the microwave range. SUMMARY OF THE INVENTION: The method of analyzing a radio signal spectrum consists in converting a radio signal into a magnetostatic wave propagating in a ferrite film placed in a magnetic field, exposing the film to optical radiation, and determining the radio signal spectrum from the spatial distribution of the transmitted optical radiation, while - the toostatic wave and optical radiation are selected collinear, create a longitudinal and transverse relative to the direction of propagation cal tim magnetostatic wave magnetic field gradients which satisfy the system of equations. 2 Il.

Description

The invention relates to radio engineering and electronics and can be used in the construction of optical and radio information processing systems, mainly the microwave range.

The purpose of the invention is to expand the frequency band of the analyzed radio signal.

Fig. 1 shows a diagram of the interaction of optical radiation and a microwave signal in a gradient magnetic field; Fig. 2 is a diagram of one embodiment of a device for analyzing a radio signal spectrum.

The device contains a transducer 1, optical prisms 2 and 3, a conductor 4, an optical radiation source 5, a lens 6, a polarizer 7, an analyzer 8, a system 9 constant

magnets, optical radiation receiver 10.

The method of analyzing the spectrum of a radio signal consists in converting a radio signal into a magnetostatic wave (MCB), spreading in a ferrite film placed in a magnetic field, introducing a broad beam of ferrite optical radiation into the film and determining the spectrum of the radio signal from the spatial distribution of the optical radiation. The direction of propagation of optical radiation and MFR is chosen to be collinear and create spatial longitudinal and transverse relative to the direction of optical radiation spatial gradients of the magnetic field, which satisfy the system of equations:

J

WITH

 about

four

.. vCOaQ / aQ.

Z Z0 + J -3 - / - TG dy; about dq dk

vn v, -7 y. KW-KotZJ-J- / dy;

“. yCOdfl Q. 4®- J-aT -aiT 1

k (Z) k0 (Z),

where k and q are the projections of the wave vector MCB on the y and z axes, respectively, the variables with the subscript o correspond to the values of the variables for y 0;

Q-left part of the dispersion law for surface MRV:

Q 2 (wg th) + ami, (k2 + q2) + a) m (wH + Hhi) l + + 2 (iy + - ft) (k2 + q2) X th (2 Xd),

where X k2 + q2 SONSht

, 2.

ftjЈ + (OnSt - O

WH Y H 4 tgu M, where d is the thickness of the ferrite film;

H (y, z) is the external magnetic field;

a) is the frequency of the MRV;

M is the saturation magnetization of a ferrite film;

Y is a gyromagnetic ratio.

The simplest type of distribution of the magnetic field is observed when (Fig. 1) a constant small gradient field is created in the transverse direction. In this case, the law of change of the magnetic field in the longitudinal direction is chosen quadratic;

H (y, z) H (o, z) +

+ H (0.2) + 27rlVb L H (0.z) 2y2 5z)

Thus, the transverse linear gradient of the magnetic field provides a one-to-one correspondence between the frequency of the MCB and the Z coordinate at which the polarization of the optical radiation is converted, and the longitudinal quadratic change of the field produces a high conversion efficiency.

If the radio signal is not monochromatic, but contains a frequency spectrum, then the polarization change occurs at different values of the Z coordinate. Determining the frequencies of the radio signal is reduced to determining the distribution of the intensity of optical radiation along the Z coordinate.

The method allows parallel analysis of the radio spectrum in real time.

As a result of the collinear diffraction of optical radiation on the MBC in those regions of the film where the phase matching condition is satisfied, the TE (or TM) waveguide mode is transformed, i.e. the polarization of the optical radiation changes. Then the optical radiation is removed from the film, using the analyzer, the spatial

the position of the transform domain and from which the spectrum of the radio signal is determined.

The magnitude, orientation and spatial gradient of the magnetic field is chosen in accordance with the center frequency and

the width of the spectrum of the analyzed radio signal.

The conversion of optical radiation occurs in a wide frequency range of the radio signal, with various

the radio signal frequencies correspond to different spatial areas of optical radiation conversion.

The width of the analyzed frequency range of the radio signal is determined by the value

transverse gradient magnetic field.

In the presence of a transverse gradient, the magnetic field in the film excites the MCB with a wave number K that satisfies the condition of spatial synchronism not at a single frequency, as in the case of a uniform field, but in a wide frequency range.

However, in the presence of a transverse gradient of the magnetic field trajectory

the propagation of the MRV becomes curvilinear, and the condition of the constant wavenumber along the direction of propagation of the optical radiation ceases to be fulfilled.

In order for the wave number of the MCB to remain fixed along the direction of propagation of the optical radiation, a longitudinal gradient of the magnetic field is created.

The presence of the transverse gradient of the magnetic field makes it possible to expand the frequency band of the analyzed radio signal. The range of analyzed frequencies A f is associated with

the differential magnitude of the magnetic field in the transverse direction ratio

Af WELL,

where, 8 MGN / E.

By creating a non-uniformity of the magnetic field in 600 Oe, it is possible to analyze the radio spectrum with a bandwidth up to Af 1.6 GHz, and these values are not the limit.

A longitudinal gradient magnetic field is created along the y axis. The distribution of the magnetic field along the y axis is chosen such that for a fixed frequency and any coordinate y, the phase matching condition is satisfied only for one value of the Z coordinate.

The device works as follows.

As the transducer 1, a YaFesCha ferrite film with a thickness of 8.7 microns grown on a non-magnetic substrate is used. Two prisms 2 and 3 of GaP are glued to the surface of the film with optical adhesive to enter and exit optical radiation from the film.

Conductor 4, 10 mm long and 30 microns in diameter, is pressed against the film surface to convert the radio signal into the MCB.

A wide flat beam of optical radiation from a source of a 5 - gas or semiconductor laser with a wavelength of А 1.15 µm is formed by a lens 6.

The polarizer 7 at the input and the analyzer 8 at the output of the device serve respectively to set the polarization of the input radiation and the spatial separation of the conversion region of the optical waveguide modes.

A constant inhomogeneous magnetic field with the required gradient is created by a system of permanent magnets 9 and SmCo, non-uniformly magnetized in length.

The intensity distribution of the output optical radiation is recorded by the receiver 10, for example, a line of photodiodes magnetized along the length

The longitudinal gradient of the magnetic field in the device is created by changing saturation according to a certain law along one side of the magnet.

The transverse gradient is achieved by using two magnets with different values of saturation induction, which are calculated using magnetostatic formulas.

The transverse gradient can also be achieved using a system of two magnets, one of which is flat and non-uniformly magnetized, and the other is made in

wedge and is located relative to the first, as shown in figure 2.

The shape and location of the magnets is calculated by the formulas of the magnetostatics or are chosen experimentally so

so that the magnetic fields they create satisfy the reduced system of equations.

The radio signal under study is fed to transducer 1 and excites in film

ferrite spreading MRV. At the same time, a TMZ mode is excited by a wide-aperture optical beam in the film. In this region of the film, where the phase-matching condition at the frequency of the input signal / Zm-PTE K (for a film with a thickness of 8.7 μm K is 300) is fulfilled, the optical waveguides of the TMZ modes are converted.

Claims (1)

Invention Formula The method of analyzing the radio signal spectrum, which consists in converting a radio signal into a magnetostatic wave propagating in a ferrite film placed in a magnetic field, exposing the film to optical radiation and determining the radio signal spectrum from the spatial distribution of transmitted optical radiation, in order to expand The bands of the analyzed frequencies, the direction of propagation of the magnetostatic wave and optical radiation are chosen collinear, the gradients of the magnetic field are created longitudinal and transverse relative to the direction of propagation of the magnetostatic wave, which satisfy the system of equations: at r9d / rk2 (  + dq (9k dy: { vi-l v p H DP / dQ. Ka-KotZoJ-J- / dy: ™ yCz) aQxaQ. c | (Z) - J-X-dy: k (Z) k0 (Z), where K and Z are the projections of the wave vector of the magnetostatic wave onto the longitudinal and transverse with respect to the direction of propagation of the magnetostatic wave of the y-axis and Z: Q is the left part of the dispersion law of a magnetostatic wave; Q 2 (uЈ-u) + uMOMb (k2 + q2) + Wm (Shn + Odp) k2 + + 2 (au + ftWOm - ft) (k2 + q2) X th (2 Xd), 0 where X k2 + q2 -4W ™ q2, a & + a) csh - a WH yH, Pcs -Lpu M, where (a is the frequency of the magnetostatic wave, d is the thickness of the ferrite film, H is the external magnetic field; M is the saturation magnetization of the ferrite film, u-gyromagnetic ratio. te / W /// M