RU2622783C1 - Cover target - Google Patents

Abstract

FIELD: military equipment.

SUBSTANCE: cover target is made in the form of a circular dielectric rod 1 sharpened at the end, densely inserted by the cylindrical part into the shorted round waveguide 2. The transverse cross section of the rod at a distance of λ₁/2 from the end of the waveguide is made at a distance of half of the smallest wavelength λ₁/2 in the waveguide of the first, long-wavelength subband, in the cylindrical part of the rod. A flat reflector made of a grid of thin conductors with square cells the size of which is less than half of the length of the smallest wavelength λ₁/2 of the first subband of waves in the waveguide and is equal to half the maximum wavelength of the second, short-wavelength subband λ₂/2 is inserted into a cut.

EFFECT: increased range of working wavelengths of the false target by 2 times.

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 of half a wavelength, to discrete values of wavelengths (Theoretical Foundations of Radar edited by Ya.D. Shirman. M., Sovetskoe Radio, 1970). Clouds form in the extra-atmospheric part of the trajectory from dipoles, 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 a narrow operating wavelength range of ± 20%, which is its drawback.

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

The technical result of the invention is an increase in the range of working wavelengths of a false target.

The technical result of the invention is achieved by fulfilling a false target (LC) in the form of a dielectric antenna with a mesh reflector.

The invention is illustrated by drawings.

In FIG. 1 shows an axial section of a false target (LC), where the notation is introduced: 1 - dielectric rod; 2 - waveguide; 3 - mesh reflector (CO).

In FIG. 2 shows the design of CO 3, where are indicated: b - the size of the square mesh cells; d is the diameter of the circular waveguide.

The technical result of the invention is achieved due to the fact that the false target contains: antenna 1, waveguide 2 and CO 3 (Fig. 1).

The false target is made in the form of a round dielectric rod, pointed at the end, tightly inserted by the cylindrical part into the shorted round waveguide to its end. At a distance of half the smallest wavelength λ _1/2 in the waveguide of the first, long-wave subband, a through cross-section is made in the cylindrical part of the rod, into which a flat reflector is tightly and coaxially inserted. The reflector is made of thin mesh wires with a square mesh size b which is less than half the smallest wave length λ _1/2 in the waveguide and the first sub-band wave is half the greatest wavelength λ _2/2 in the second waveguide, the short-wavelength sub-band. Wavelengths λ _1/2 and λ _2/2 satisfy the inequality:

lambda _2/2 = b <λ _1/2,

where λ ₁ - the smallest wavelength in the waveguide of the first, long-wavelength subband wavelengths;

λ ₂ - the largest wavelength in the waveguide of the second, short-wave sub-range of wavelengths;

b - the size of the square cells of the mesh reflector.

The rod 1 is made of a dielectric material with low losses (the loss tangent is less than 10 ^-3 ), for example, polystyrene or fluoroplastic. The length of the cylindrical part of the dielectric rod is equal to the length of the waveguide. The length L of the conical part of the rod is more than a quarter of the wavelength in air, the smallest wavelength λ _{01 of the} first long-wavelength subband of the LC.

CO 3 is made in the form of a flat round grid of thin conductors with a square mesh size b and diameters equal to the diameter of the waveguide (Fig. 2). The longest wavelength in the waveguide of the second subband λ ₂ is 2b.

The width of the radiation pattern of the LC at half power 2θ ° is estimated by the formula

where λ _cf is the average wavelength in the part of the rod protruding from the waveguide of length L.

The length of the largest critical wave λ _c in a circular waveguide of the lowest order (main wave) is:

where d is the minimum allowable diameter of the waveguide.

The wavelength in the waveguide λ with a rod of dielectric material, with a relative permittivity ε, is equal to:

λ _about - the wavelength in the air.

The maximum value of the EPR of the LC at a wavelength of λ ₀ in air, the diameter of the waveguide and CO equal to d, and the antenna gain k, is determined by the formula

- ЭПР СО;Where

- ESR WITH;

d is the diameter of the waveguide and CO;

λ ₀ is the wavelength in air;

k is the antenna gain in power.

Formulas (2-5) are borrowed from the book of Southworth J. K. "Principles and applications of waveguide transmission", M., "Soviet Radio, 1955").

The algorithm for calculating the effective scattering surface (EPR) of the LC, according to the given values of the smallest wavelength of the first subband of wavelengths and the largest wavelength of the second subband

1. Set the value of the smallest wavelength λ ₀₁ in the air of the first subband.

2. Using the value of wavelength λ ₀₁ in air, determine the smallest permissible waveguide diameter d, with a rod, through the critical wavelength λ _s in a circular waveguide, for a lower-order wave (main wave) (3).

3. Calculate the value of the smallest wavelength λ ₁ in the waveguide, with the rod (4).

4. According to the wavelengths λ ₁ and λ ₂ , determine the size of the square cell b of the grid CO 3 (1).

5. By the value of the largest wavelength λ ₂ in the waveguide of the second subband, calculate its length in air λ ₀₂ (4).

6. The maximum values of the ESR of the LC are calculated from the wavelengths λ ₀₁ and λ ₀₂ (5).

Calculation of the EPR of a LC at wavelengths λ ₀₁ and λ _{02 in} air

1. The value of the smallest wavelength of the first subband λ ₀₁ in air is selected, for example, equal to 20 cm

2. By the value of the wavelength λ ₀₁ determine the smallest allowable diameter of the waveguide d with the rod, through the critical wavelength λ _s in the circular waveguide, determine by the formula (2)

d = λ _c / l, 71

For a wavelength in air of λ ₀₁ = 20 cm, the diameter of the waveguide d must be at least λ _s / 1.71 = 20 cm / 1.71 = 12 cm.

3. By the formula (3) calculate the value of the smallest wavelength λ ₁ in the waveguide with the rod, which is equal to:

λ ₁ = 1.84⋅λ _c ⋅λ ₀₁ / π⋅d√ε = 1.84⋅1.71⋅20 cm / π⋅√2.5 = 63 cm / π⋅√2.5 = 63 cm / 3.14π⋅1.58 = 13 cm.

4. For a given value of the largest wavelength λ _{02 of the} second subband in the air, for example 15 cm, calculate its value λ ₂ in the waveguide according to the formula (4)

λ ₂ = l, 84⋅λ _c ⋅λ ₀₂ / π⋅d√ε = 1.84⋅1.71⋅15 cm / π⋅√ε = 47.2 cm / 3.14⋅1.58 = 9, 5 cm

5. The values of λ ₁ and λ ₂ (1) determine the size of the square cell b of the grid STR:

λ _2/2 = b <λ _1/2 or 4,75 = b <6,5 cm.

6. According to the formula (5), the maximum values of the EPR of the LC are calculated from the value of the wavelength λ ₀ in air and the antenna gain k = 2:

,

,

The ESR of the LC at the shortest wavelength λ _{01 of the} first subband in air is:

The ESR of the LC at the longest wavelength λ _{02 of the} second subband in air is:

.

.

и

их выравнивают путем нанесения на торец волновода радиопоглощающего материала с коэффициентом отражения по мощности (в примере в 4,5 раза).If necessary, equal EPR values

and

they are aligned by applying to the end of the waveguide a radio-absorbing material with a power reflection coefficient (4.5 times in the example).

In order for the leaked part of the wave energy of the first subband to be reflected by the end of the waveguide in-phase to reflection from CO 3, the distance to the end of the waveguide should be equal to half the wavelength λ _1/2 = 6.5 cm. The wavelengths of the second subband shorter than 2b pass through CO, are reflected from the end of the waveguide and exit through CO back. By changing the size of the square cells b, I adjust the maximum wavelength of the second subband.

Features of the claims

The false target is made in the form of a round dielectric rod, pointed at the end, tightly inserted by the cylindrical part into the shorted round waveguide to its end, and at a distance of half the smallest wavelength λ _1/2 in the waveguide of the first long-wave subband, from the end of the waveguide in the cylindrical part of the rod a transverse cross-section through which a flat reflector made of a grid of thin conductors with square cells whose size b is less than half the smallest length ins wavelength λ _1/2 first sub-band wave in the waveguide, and is half the wavelength of the second greatest short wave subband λ _2/2, the wavelength λ _1/2 and λ _2/2 satisfy the inequality:

lambda _2/2 = b <λ _1/2,

where λ ₁ - the smallest wavelength in the waveguide of the first, long-wavelength subband wavelengths;

λ ₂ - the largest wavelength in the waveguide of the second, short-wave sub-range of wavelengths;

b - the size of the square cells of the mesh reflector.

Claims (5)

A false target containing a reflector, characterized in that it is made in the form of a round dielectric rod, pointed at the end, tightly inserted by the cylindrical part into the shorted round waveguide to its end, and at a distance of half the smallest wavelength λ1 / 2 in the waveguide, of the first long-wave subband, from the end of the waveguide, in the cylindrical part of the rod, a through cross-section is made, into which a flat reflector made of a grid of thin conductors with square cells is tightly and coaxially inserted, size of which b is less than half the length of the smallest wavelength λ1 / 2 of the first subband in the waveguide and is equal to half the largest wavelength of the second short-wave subband λ2 / 2, wavelengths λ1 / 2 and λ2 / 2 satisfy the inequality: λ2 / 2 = b <λ1 / 2, where λ1 is the smallest wavelength in the waveguide of the first, long-wavelength subband of wavelengths; λ2 is the longest wavelength in the waveguide of the second, short-wave sub-band of wavelengths; b - the size of the square cells of the mesh reflector.

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