RU2594382C1 - Adjustable microwave delay line on surface magnetostatic waves - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention can be used for processing signals in wideband microwave systems of various purpose. Invention core is that adjustable microwave delay line on magnetostatic waves comprises a dielectric substrate fixed on the basis with parallel and spaced from each other microstrip converters of surface magnetostatic waves (SMSW) arranged on it, a magnetoactive element made in the form of rectangular plate from dielectric with a film of yttrium iron garnet applied on one side, which is connected to the means of displacement relative to the base and faces the SMSW converters with the film, a permanent magnet of magnetic biasing arranged in the area of the magnetoactive element location, herewith at the free surface of the yttrium iron garnet film a periodic structure is formed as a row of grooves of the same size, the means of the magnetoactive element displacement relative to the base is made able to rotate in the plane of the dielectric substrate, herewith the minimum delay time corresponds to the position of the longitudinal axis of the grooves parallel to the SMSW converters axis, and the permanent magnet is located so that the bias field vector lies in the plane of the dielectric substrate and coaxially with the SMSW converters microstrips.

EFFECT: technical result is controlling the delay time of a microwave signal without changing the field and the permanent magnet values.

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Description

The invention relates to radio engineering and can be used as a functional element for processing signals in broadband microwave systems for various purposes.

It is known that devices on magnetostatic waves - surface (PMSV), direct bulk (PMSV), reverse bulk (OOMSV) propagating in ferrite films, are promising for the processing of microwave signals in the range of units - tens of GHz. Various devices for this purpose are described, including the use of various regulatory elements to influence the characteristics of the MSW. Thus, a tunable delay line on OOMSV (US 3353118, Olson et al., 1967) is known, containing a single-crystal ferrimagnetic rod acting as a medium for transmitting a microwave signal and having input and output microwave converters, means for creating a magnetic field in the longitudinal direction of the rod and means for changing the magnitude of the specified magnetic field to adjust the delay time. In the device (US 3935550, Adam, et al., 1976), a magnetostatic delay line (based on a thin ferrimagnetic film) with a linear dependence of the delay time on the signal frequency is used to compensate for signal dispersion in the external microwave path. Changing the magnitude of the magnetizing field allows you to adjust the delay time of the signal.

A device is described (US 4400669, Daniel et al., 1983), using the propagation of PMSV in a film of yttrium iron garnet (YIG) of a given thickness, placed in a constant magnetic field. It includes two transducers for exciting and receiving PMSV in a film and a metal screen placed between the transducers. By choosing the gap between the surface of the magnetic film and the metal screen, the linearity of the group delay versus frequency is increased.

Also known is the delay line at OOMSV (US 4605911, JIN KORDA, 1986), including a cascade of elements operating on different wave modes to obtain a dispersion-free delay line, and a magnetic system that provides uniform magnetic flux to control the delay time. A delay line at the MSW is described (RU 2045814, Vyzulin et al., 1995), in which the magnetic system creates an inhomogeneous magnetic field applied perpendicular to the surface of the ferrite film, and also differs by the location of the input antenna at an angle to the longitudinal axis of the delay line, while the output antenna located on the caustic of the received wave. However, the possibility of changing the delay time of the signal in this design is not described.

It should be noted that the above MSV devices have a common drawback - a change in the delay time of the microwave signal requires additional consumption of a constant electric current by the magnetic system. It is also known to control the parameters of devices on the MSW (insertion loss, delay time) by mutual translational movement of the substrates with the converters (see, for example, SU 1552958, Kuban State University, January 27, 2001; SU 1596426, LPI named after Kalinin, September 30, 1990), which is technologically difficult, and in addition, at the same time inappropriately alters the configuration of the magnetic field and its heterogeneity.

Partially indicated disadvantage can be eliminated by means of a mechanically movable permanent magnet. Thus, an adjustable delay line for PMSV is described in the generator design (US 4028639, Hagon, Haworth, 1977 - prototype), which is used as a phase shifter in the feedback circuit. The frequency of the generator is tuned using a screw that changes the distance between the poles of the magnet and, as a result, the frequency band in which the PMSV can propagate. In this case, the distance between the input and output converters of the PMSV can be mechanically changed to provide the ability to adjust the phase of the signal passed through the delay line. The disadvantage of this design is the need to use precision mechanical systems to move both the pole of the magnetic system (in this case, significant mechanical effort may be required) and the microstrip converter.

The present invention is directed to the improvement of an adjustable delay line on surface magnetostatic waves.

The patented adjustable microwave delay line for magnetostatic waves contains a dielectric substrate mounted motionlessly on the base with microstrip surface magnetostatic wave converters (PMSV) located parallel to it and spaced from each other, and a magnetically active element made in the form of a rectangular dielectric plate coated on one side a film of iron-yttrium garnet (YIG) associated with a means of movement relative to the base and facing the film to the transform ers MSSW, a permanent magnet bias arranged in the area of finding magnetically active element.

The difference is that on the free surface of the YIG film of the magnetically active element a periodic structure is formed in the form of a series of grooves of the same size, the means for moving the magnetically active element relative to the base is rotatable in the plane of the dielectric substrate, while the shortest delay time corresponds to the position of the longitudinal axis of the grooves parallel to the axis of the PMSV transducers, and the permanent magnet is located so that the vector of the bias field lies in the plane of the dielectric spacers and coaxially to microstrips of PMSV converters.

The delay line can be characterized by the fact that the film of iron-yttrium garnet has a saturation magnetization of 600-1800 G and its thickness is 6-20 μm, as well as the fact that the grooves have a period of 5-15 μm, a width of 2-6 μm, and their depth is 0.05-0.2 film thickness.

The technical result of the invention is the ability to control the time delay of the microwave signal without changing the magnitude of the field and the position of the permanent magnet due to changes in the internal magnetic field in the film of yttrium iron garnet.

The invention is illustrated in the figures, where

FIG. 1 shows the design of the delay line for the PMSV;

FIG. 2 - shape and dimensions of the grooves of the surface periodic structure, view along arrow A;

FIG. 3 - topology of the structure, top view;

FIG. 4 - dispersion dependences of the MSSW constructed on the basis of experimental measurements for various values of the angle φ;

FIG. 5 - waveforms of the PMSV signals propagating in the layout of the delay line with a distance between microstrip converters of 4 mm, obtained with a constant magnetic field of 700 Oe and various values of the angle φ.

The design of the device is shown in FIG. 1, where 1 is a dielectric substrate mounted motionless on a base (not shown); 2 - microstrip line, 3 and 4 - input and output converters, 5 - rectangular dielectric plate; 6 - YIG film; 61 — grooves of the surface periodic structure; 62 - the longitudinal axis of the grooves 61; 7 - means for moving the plate 5 with the film 6 YIG; 8 - permanent magnet. Pos. 9 shows the direction of the magnetization field H created by the magnet 8.

The surface periodic structure is made on the YIG film 6 in the form of parallel grooves 61, the depth of which is 0.05-0.2 of the film thickness 6. The grooves 61 are placed parallel to the axis 62 of the extended structure, at the ends of which are converters 3, 4 connected to the microwave path through microstrip lines 2.

The YIG film has a thickness s = 6–20 μm with a saturation magnetization of 1600–1800 G. The grooves have a period of d = 5-15 μm, a width of w = 2-6 μm and a depth of h = 0.4-l, 3 μm, while the source of a constant magnetic field provides a strength of at least 700 E. The rotation of the plate 5 is carried out using 7 movements.

The device operates as follows. A plate 5 with a YIG film 6 with a surface structure in the form of grooves 61 is placed on the substrate 1, where the input and output microstrip converters 3,4 are formed. The axis 62 of the groove is perpendicular to the direction H of the constant magnetic field of magnet 8 (the angle φ between the axis of the groove and the direction is 90 degrees). In such a geometry, the internal magnetic field in the regions between adjacent grooves turns out to be inhomogeneous due to the appearance of demagnetization fields (Amikam Aharoni, "Demagnetizing factors for rectangular ferromagnetic prisms" // J. Appl. Phys. 83 (1998) 3432), and the region of heterogeneity extends to the entire thickness of the film, so that the internal magnetic field in the YIG film becomes periodically inhomogeneous along the entire propagation path of the MSSW.

The dispersion dependence of the PMSV for this case is shown in FIG. 4, where the values of φ are indicated near the curves. With a change in the angle φ, the degree of heterogeneity of the internal field decreases, which leads to a change in the slope of the dispersion curve of the MSSW and, accordingly, to a change in the value of the group velocity of the MSSV at a fixed frequency.

It is known that the signal delay time t is determined by the expression t = L / V, where L is the mean free path, V is the group velocity, V = dq / df. Therefore, when the angle φ changes, the delay time of the signal will change due to a change in the group velocity of the MSSW. In FIG. Figure 5 shows the PMSV waveforms for various values of the angle φ. It can be seen that when the plate 5 with the grooves 61 is rotated, the delay changes from 400 ns at φ = 90 ° to 50 ns at φ = 35 °.

Thus, the presented data indicate the achievement of the technical result of the invention — the ability to control the delay time of the microwave signal in the frequency band without changing the magnitude of the magnetization field due to a change in the internal magnetic field in the film of yttrium iron garnet when the angle between the direction of the constant magnetic field and the longitudinal axis of the grooves changes. This possibility expands the range of functions of devices on spin waves, promising for processing microwave signals.

Claims (3)

1. Adjustable microwave delay line on magnetostatic waves, containing a dielectric substrate mounted motionlessly on the base with microstrip surface magnetostatic wave transducers (PMSV) located parallel to it and spaced from each other, a magnetically active element made in the form of a rectangular dielectric plate coated on one the side of the film of iron-yttrium garnet associated with the means of movement relative to the base and facing the film to the transducers PMSV, tinuous biasing magnet disposed in the area of finding magnetically active element,
characterized in that
a periodic structure in the form of a series of grooves of the same size is formed on the free surface of the iron-yttrium garnet film, the means for moving the magnetically active element relative to the base are rotatable in the plane of the dielectric substrate, the shortest delay time corresponding to the position of the longitudinal axis of the grooves parallel to the axis of the PMSV transducers, and a permanent magnet located so that the vector of the magnetization field lies in the plane of the dielectric substrate and coaxially with the microstrip reobrazovateley MSSW. 2. The delay line according to claim 1, characterized in that the iron-garnet garnet film has a saturation magnetization of 600-1800 G, and its thickness is 6-20 microns. 3. The delay line according to claim 1 or 2, characterized in that the grooves have a period of 5-15 microns, a width of 2-6 microns, and their depth is 0.05-0.2 film thickness.

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