RU2612350C1 - False target - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: false target is designed as a short-circuited antenna of the surface waves and comprises a circular dielectric rod with a conical end tightly inserted into the circular waveguide to the end with its cylindrical part. The length of the cylindrical rod part is equal to the length of the waveguide, the length of the conical part is a quarter larger the maximum wavelength in the range air of the false target. N through transverse incisions are made in the rod. The mesh reflectors are tightly inserted in the incisions in the form of the flat round meshes of thin wires with different sizes and the square cells with diameters equal to the waveguide diameter. The mesh reflector of the most long-wave sub-band is inserted in the first, from the waveguide aperture, through incision, the subsequent incisions are made in the rod at the distance equal to the minimum wavelength in the circular waveguide (λig) min of the i-th wave subband. The maximum (λig) max and minimum (λig) min sub-band wavelengths and the sizes of the mesh reflector square cells bi satisfy (λig+1) max = 2bi = (λig) min.

EFFECT: increasing the wavelength subbands of the false target.

2 dwg

Description

The invention relates to military equipment, namely, to designs of false targets designed to divert electronic weapons from a real target, which increases the likelihood of overcoming the enemy’s missile defense (ABM) target.

False targets are known, made in the form of dipole reflectors, which are made of conductive filaments or strips of half a wavelength, to discrete values of wavelengths (Theoretical Foundations of Radar edited by Ya.D. Shirman. M., Soviet Radio, 1970). Clouds are formed from dipoles on the extra-atmospheric part of the trajectory, which mask the target at discrete wavelengths, but cannot imitate the target according to its signal characteristics, which is their drawback.

The known design of a false target, made in the form of a trihedral corner reflector, adopted as a prototype of the invention (Theoretical foundations of radar edited by Ya.D. Shirman. M., Soviet Radio, 1970). The false target contains a trihedral corner reflector. The prototype has an operating range of wavelengths of ± 20% width, in which the deviation of the radiation pattern from the maximum does not exceed 3 dB.

The sign of the prototype, coinciding with the sign of the invention is a reflector.

The technical result of the invention is the increase of the sub-wavelength ranges of the false target by N + 1 times (N> 0).

The invention is illustrated by drawings.

In FIG. 1 shows a longitudinal axial section of a false target (LC), where the notation is introduced: 1 - the first mesh reflector; 2 - second mesh reflector; 3 - dielectric rod; 4 - squirrel-cage round waveguide.

In FIG. 2 shows the design of the mesh reflector, where are indicated: bi - the size of the square cells of the grids of the i-th mesh reflector (i = 1, 2, ..., N); di is the diameter of the i-th mesh reflector.

The technical result of the invention is achieved due to the fact that the false target (LC) contains a shorted surface wave antenna, which includes a circular waveguide 4, a dielectric rod 3 and N mesh reflectors (CO) (Fig. 1).

The rod has a cylindrical and conical part. The length of the cylindrical part of the rod 3 is equal to the length of the waveguide 4, the length of the conical part of the rod L is more than a quarter of the maximum wavelength in the air of the LC range.

The rod 3 is made of dielectric material with low losses (the loss tangent is less than 10 ^-3 ), for example, polystyrene or fluoroplastic.

N through transverse sections are made in the rod, into which mesh reflectors (CO) are tightly and coaxially inserted in the form of flat round grids of thin conductors with different sizes of square cells bi and diameters equal to the waveguide diameter 4 or less (Fig. 2).

The first through section is made at a distance from the edge of the waveguide aperture, sufficient for fastening in the waveguide the front of the rod with a tapered end, into which the first mesh reflector of the longest wavelength subrange of the false target is tightly inserted.

Subsequent sections in the rod are made at a distance equal to the minimum wavelength in the circular waveguide (λig) max of the i-th subband of the LC waves, where i = 1, 2, ..., N.

The maximum (λig) max and minimum (λig) min wavelengths of the subbands and the sizes of the square cells bi of the mesh reflectors satisfy the equality

From this equality it follows that the minimum (λig) min and maximum (λig + 1) max wavelengths in the waveguide and the doubled value of the size bi of the square cells of the i-th subband of the waves are equal.

The maximum wavelength in the waveguide in the i + 1th subband is equal to the minimum wavelength in the previous i-th subband.

The wavelength in the circular waveguide λg through the wavelength in air λo and the critical wavelength in the waveguide λcg are determined by the formula

where k is the first root of the Bessel function of the first kind J1 (π⋅d⋅ / λo) = 0 of the main wave in a circular waveguide, which is equal to 1.841;

λcg is the critical wavelength in the waveguide;

λо - wavelength in air;

d is the diameter of the circular waveguide;

ε is the relative dielectric constant of the core material of the LC;

v is a parameter equal to the numerator of the fraction of formula (2).

The largest working wavelength (λ1о) max in air, which can pass through the transmission band of a waveguide of diameter d, is limited by its critical wavelength λcg:

The critical wavelength λcg in the waveguide does not propagate, decays exponentially. For the maximum wavelength in the air of the first long-wave subband, from the condition of permissible losses - fractions of dB per wavelength, its value is taken to be shorter than the critical wavelength by 15-20%. By changing the size of the square cells bi СО within 0.5 (λig) min> bi> 0.25 (λig) min, the minimum wavelength (λig) min of the i-th subband of the LC is controlled.

Under the condition 0.5 (λig) min> bi> 0.25 (λig) min, part of the power of the waves incident on the LC seeps through the i-th CO into the next i + 1 subband so that the waves (λig) min are reflected from the next CO in the phase, with reflections from the previous RM, the distances between adjacent RMs should be equal to 0.5λ (λig) min.

With square bi cells of 0.25 (λig) min or less, more than 99% of the incident wave power is reflected from the CO.

Let us determine the permissible minimum diameter of a circular waveguide with a minimum wavelength in air of the first subband (λ1o) min, for example, equal to 30 cm. For this, we increase the value of the critical wavelength λcg of the waveguide in comparison with the wavelength in air λ1o by 15% - 35 cm. Using the value of λcg, the minimum diameter d of the circular waveguide is determined by the transformed formula (3) to

An example of determining the signal characteristics of the LC: EPR and the angular width of the radiation pattern in the sub-bands of the waves.

By the value in air of the minimum wavelength in the 1st subband is 30 cm and the maximum values of wavelengths in the 2nd and 3rd subranges of 15 cm and 7.5 cm and the square cell sizes bi equal to 0.25 ( λig) min, according to formula (2), the wavelengths in the waveguide are determined in 3 subranges, which are (λ1g) min = 22.8 cm, (λ2g) max = 11.8 cm and (λ3g) max = 5.6 see. The sizes of the bi cells in the ith CO are respectively equal: b1 = 5.7 cm, b2 = 2.95 cm.

(λoi) ЛЦ на длине волны λoi для i-х СО в форме диска определяют по формуле (5)The maximum value of the EPR

(λoi) LC at the wavelength λoi for i-th CO in the form of a disk is determined by the formula (5)

(λoi) - максимальное значение ЭПР ЛЦ на длине волны в воздухе λoi;Where

(λoi) is the maximum value of the EPR of the LC at a wavelength in the air of λoi;

Ki is the antenna gain in power at the wavelength λoi;

di is the diameter of the i-th subband of the waves;

λoi is the wavelength in air of the i-th subband of waves.

(λo1) равноWith values equal to π ³ = 31; (Ki) ² = 16; (d1 / 2) ⁴ = 10 ⁴ cm; (λо1) ² = (30 cm) ² , value

(λo1) is equal

.

.

The width of the radiation pattern (MD) of the LC, at a half power of 2θ ° at a wavelength, is estimated by the formula

where λcp1 is the average wavelength (30 cm + 30 / √ε) / 2 = (30 cm + 30 / √2.5) / 2 = (30 cm + 19) / 2 = 24.5 cm, at the same value length L, the angular width of the beam 2θ ° at half power is 30 °.

The angular width of the LC LC, at half power 2θ °, is equal to 21 ° in the second subband at L = 2λ2ср, and 15 ° in the third at L = 3λ3ср.

Formulas 2, 3, 5, and 6 are borrowed from monographs: J. Southworth, “Principles and Applications of Waveguide Transmission,” M., Soviet Radio, 1955, Y.N. Felda and L.S. Benenson. Antenna feeder devices. WWAI publication prof. N.E. Zhukovsky, 1959 and E.N. Maiselsa, V.A. Torganova, Measuring the dispersion characteristics of radar targets, M., Sov. Radio, 1972.

Features of the invention

The reflector is made in the form of a short-circuited surface wave antenna, which contains a round dielectric rod with a tapered end, a cylindrical part tightly inserted into the circular waveguide to the end.

The rod is made of dielectric material with low losses, the length of the cylindrical part of the dielectric rod is equal to the length of the waveguide, the length of the conical part of the rod is more than a quarter of the maximum wavelength in the air of the false target range.

N through cross sections are made in the rod, into which mesh reflectors are made densely and coaxially, made in the form of flat circular grids of thin conductors with different sizes of square cells and diameters equal to the diameter of the waveguide or less.

The first through section is made at a distance from the edge of the waveguide aperture, sufficient for fastening in the waveguide the front of the rod with a tapered end, into which the first reflector of the longest wavelength subrange of the false target is tightly inserted.

Subsequent sections are made in the rod at a distance equal to the minimum wavelength in a circular waveguide (λig) min of the i-th subband of waves, where i = 1,2, N.

The maximum (λig) max and minimum (λig) min wavelengths of the subbands and the sizes of the square cells bi of the mesh reflectors satisfy the equality

(λig + 1) max = 2bi = (λig) min.

Claims (1)

A false target containing a reflector, characterized in that the reflector is made in the form of a short-circuited surface wave antenna, which contains a round dielectric rod with a tapered end, a cylindrical part tightly inserted into the circular waveguide to the end, and the rod is made of dielectric material with low loss, the length of the cylindrical part of the dielectric rod is equal to the length of the waveguide, the length of its conical part is more than a quarter of the maximum wavelength in the air of the range of the false target, in addition, in the rod N through transverse cuts were not made, into which mesh reflectors made in the form of flat circular grids of thin conductors with different sizes of square cells and diameters equal to or less than the diameter of the waveguide were inserted densely and coaxially, the first through section being made at a distance from the edge of the waveguide aperture sufficient for fastening in the waveguide the front of the rod with a tapered end, a mesh reflector of the longest wavelength subrange of the false target is tightly inserted into the first section, the subsequent sections filled in the rod at a distance equal to the minimum wavelength in the circular waveguide (λig) min of the i-th subband of the false target waves, where i = 1, 2, ..., N, in addition, the maximum (λig) max and minimum (λig) min the wavelengths of the subbands and the sizes of square cells bi of the mesh reflectors satisfy the equality (λig + 1) max = 2bi = (λig) min.

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