RU36533U1 - RADAR REFLECTOR - Google Patents

Description

The utility model relates to radar and can be used as a reference radar reflector (RO), which has the properties of a partially nonreciprocal object.

The closest in technical essence to the proposed device is RO 1, which represents a passive re-emitting conical horn antenna. The disadvantage of the described construction is that it cannot serve as a reference PO possessing encoded partially nonreciprocal properties.

The technical result, the achievement of which this solution is directed, is to impart partially partially nonreciprocal polarizing properties to the PO.

The radar reflector, which is a passive re-emitting conical horn antenna, is characterized in that the design includes a segment of a circular waveguide with two built-in rectangular waveguides, while the first rectangular waveguide is designed to isolate a linear vertically polarized electromagnetic wave component and is combined with a circular waveguide using sections of a smooth transition from round to rectangular waveguide, and the second rectangular waveguide is designed to Highlighted linear horizontally polarized component of the electromagnetic wave

and connected to the first waveguide using a rectangular waveguide path with a twist of 90 °, which includes a ferrite valve.

It is known that the scattering operator 2 describes the most fully polarized and energy characteristics of the scattering of the target, the projection of which onto a particular polarization basis is the scattering matrix S, the elements of which are generally complex variables

In cases where the propagation region of the incident and scattered waves is nonreciprocal, the backscattering matrix (MOR) of an arbitrary medium has an asymmetric shape 2, with 5.2 Sj ,.

In work 3, a parameter is introduced, called the nonreciprocity coefficient, which is determined according to the expression

, | 2 2.Q.5. (S ,, - S ,,

,,, f

The parameter allows to classify objects into:

-reciprocal, for which O;

-absolutely non-reciprocal, for which 1;

5 ,, iSi2

(1)

 22.

- partially nonreciprocal, for which lies in the range from zero to unity.

In order to assess the scattering characteristics of objects for which 9 O,

it is necessary to preliminarily conduct external calibration of the radar station with the help of a reference radar reflector having partially nonreciprocal properties. As such an object, the PO shown in FIG. 1, FIG. 2, FIG. 3, FIG. 4.

In FIG. 1 shows the design of the PO (side view), in FIG. 2 shows the design of the PO (bottom view), in FIG. 3 shows the design of the RO (front view), in FIG. 4 shows the design of the PO (top view), in FIG. 5 shows a waveguide twist of 90 °.

In FIG. 1, FIG. 2, FIG. 3, FIG. 4 in different planes shows the design of the RO, which includes a conical horn antenna 1, structurally combined with a waveguide device for separating an electromagnetic wave (EMW) into linear orthogonally polarized components. This device is a segment of a circular waveguide 2 with two built-in waveguides of rectangular cross-section 4 and 5, while a rectangular waveguide 5 is designed to isolate a linear vertically polarized EMW component and is combined with a circular waveguide 2 using section 3 of a smooth transition from round to rectangular waveguide, . The waveguide 4 is designed to isolate the linear horizontally polarized EMF component and is connected to the waveguide 5 using a rectangular waveguide path 6, which includes a 90 ° 7 waveguide twist and a ferrite gate 8. A typical waveguide twist is shown in FIG. 5.

Assuming that waveguides 2, 4, 5, 6 do not have structural inhomogeneities, the reflection coefficient of the electromagnetic field from the ferrite gate 8 is negligible, and the conical bead antenna 1 is aligned with the external environment and has an axisymmetric radiation pattern, the operation of the device can be described as follows. The electromagnetic wave, captured by the aperture of the antenna 1, enters the circular waveguide 2 (with the type Nc), where it is divided into orthogonally polarized linear components. The wave excited in waveguide 4 (with Nu type) passes through waveguide path 6, which includes 90 ° twist and ferrite gate 8 in the direction of waveguide 5 without significant attenuation. At the same time, the wave excited in waveguide 5 (with the Nu type), passing through the ferrite gate 8 in the direction of waveguide 6, will be completely absorbed 4, 5. The electromagnetic wave propagating through the rectangular waveguide path enters the circular waveguide (with the type НЦ), with subsequent re-emission of the horn antenna 1. In order to excite the circular waveguide included in the design of the reflector antenna with one type of waves I ,,, it is necessary that the radius of the section r of waveguide 2 lies within 0.293-I g 0.383-I 6 (where I is the length waves). The smooth transition section 3 from round to rectangular waveguide is designed to reduce reflections from the junction of the waveguides. Backscatter matrix as follows

-j-k-l

m ,,,.

S M

Vth - Johns matrix of waveguide twisting

the formation of the polarization state of the vector component of the EMW to the orthogonal, when propagating in the waveguide path); 2-5th waveguide 5; M, 4th waveguide 4;

A - EMF transmission coefficient in the ferrite valve in the forward direction (i.e., from waveguide 6 to waveguide 5);

B is the transfer coefficient of electromagnetic wave in a ferrite valve in the opposite direction (i.e., from waveguide 5, waveguide 6);

. 27G

k wave number;

A is the wavelength;

-J-k-l

2-4

Ah

(3) the Jones matrix of the transition from round 2 to the rectangle; the Jones matrix of the transition from round 2 to the rectangle S of such a reflector can be determined 7 (takes into account

Oh in

S

Oh

As can be seen from (4), the MPA has an asymmetric form {AFV}, which is a manifestation of the nonreciprocal properties of the reflector.

The power flux density of the reflected RO EMF P is associated with the horizontal and vertical components of the intensity E and E incident on the EMF 2 object by the ratio:

E, g E, o G

I.

ir IB G G

 - sign of the Euclidean transformation; - a sign of complex pairing. Substituting expression (6) into (5) we obtain

P Elf, A + E-B

Thus, the power flux density of the reflected EMF P depends on the coefficients A and 5, and, in the general case, is less

density

flow

(4)

I g

(5)

(6)

(7)

Emv

falling

power Considering that it is always possible to choose k-l satisfying condition i -k-l e - 1, the expression for S takes the form: Graves matrix defined through MP S of the object 2 F F Elj, +. In ir B

ferrite valve, for which A 1, 5 0 we have:

Jaz -, V

Physically, this means that EMW is captured by the aperture of the antenna, undergoes a polarization transformation, which consists in the absorption of a vertically polarized component, and then re-emitted. In this case, the horizontal vector component of the EMW changes its state to orthogonal.

Substituting the values of the elements of MPA 5 of the form (4) in the expression (2) we obtain:

2- (And)

From (9), the square of the absolute value of the nonreciprocity coefficient 3 PO is determined by the wave transmission coefficients in the forward (A) and reverse (B) directions of the ferrite gate. In the case of an ideal ferrite gate (1, 5 0), the MPA will be determined in the form:

S

For MPAs of the form (10) 111 0.5. Thus, this PO has

properties of a partially nonreciprocal object

iuD

(8)

In - Af

(9)

0o

(10)

1OF) application of the ideal

nonreciprocal polarization properties, which allows the use of a reflector as a reference radar reflector, possessing the properties of a partially nonreciprocal object.

LIST OF USED LITERATURE.

1.Kobak V.S. Radar reflectors. - M.: Soviet Radio, 1975.-248 p.

2.Bogorodsky V.V., Kanareikin D.B., Kozlov A.I. Polarization of the scattered and intrinsic radio emission of terrestrial iokrov.- L .: Gidrometeoizdat, 1981

3.Khlusov V.A. Parameterization of the backscattering matrix of nonreciprocal media // Atmospheric and Ocean Optics 8, No. 10 1995, 1441-1445

4.Mikaelyan A.L. Theory and application of ferrites at microwave frequencies. - M.-L .: - Gosenergoizdat, 1963 .-- 664 p.

5. Lebedev I.V. Technique and microwave devices. - M.: - Higher school, 1970. - 440 p.

6. Aizenberg G.Z., Yampolsky V.G., Tereshin O.N. VHF antennas. Part 1-M .: Communication, 1977

Claims (1)

A radar reflector, which is a passive re-emitting conical horn antenna, characterized in that the design includes a segment of a circular waveguide with two built-in rectangular waveguides, while the first rectangular waveguide is designed to isolate a linear vertically polarized component of the electromagnetic wave and is combined with a circular waveguide using sections of a smooth transition from round to rectangular waveguide, and the second rectangular waveguide is designed to I select the linear horizontally polarized component of the electromagnetic wave and connects to the first waveguide using a rectangular waveguide path with a twist of 90 °, which includes a ferrite gate.