RU2195054C2 - Method for separate zero generation in sum and difference directivity patterns of single-pulse phased antenna array - Google Patents

Abstract

FIELD: antenna engineering. SUBSTANCE: adaptive P-antenna subarrays are discriminated at edges of N-antenna phased array, their output signals are weighed by means of complex weighing devices, complex weighting coefficients of adaptive subarrays being chosen from condition in which first and second beams of single-pulse group in P noise directions u $\genfrac{}{}{0ex}{}{\text{p}}{\text{sba}}$ (p = 1,2, ..., P) and in P directions u₀ symmetrical to them in generalized coordinate relative to boresight 2u₀-u $\genfrac{}{}{0ex}{}{\text{p}}{\text{sba}}$ equal zero. EFFECT: enhanced precision of boresight orientation during zero generation in directivity patterns of mentioned arrays. 3 dwg

Description

 The invention relates to antenna technology and can be used to solve the problem of increasing the accuracy of orientation of the equal-signal direction (RSN) during the formation of zeros in the radiation patterns (MD) of monopulse phased antenna arrays (PAR).

 There is a method of zeroing the phased ARs [1], which is based on the selection in the initial N-elementary arrays of two adaptive sublattices located symmetrically with respect to the center of the initial ARs of M elements each and introducing phase corrections into the selected 2M elements, which ensure zero formation in a given direction. The disadvantages of this method are the displacement of the main maximum of the ND during zero formation, reaching 10% of the beam width at half power level, as well as a significant complication of the implementation of this method in the case of the formation of two or more zeros.

The closest in technical essence to the claimed method is a method for the separate formation of zeros in the total and difference radiation patterns of monopulse antenna arrays [2], which is based on dividing the signals received by each emitter into two channels, summing the signals from the same outputs of the dividers with their weight coefficients providing two beams forming a monopulse group rejected from PCH to the generalized coordinate ^± Δu, where Δu - distance rays maxima to PCH, and after uyuschem formation of the sum and difference DN.

In the known method of generating zeros, the weighting coefficients of the signals received by each emitter in the beam forming channels are chosen equal to the algebraic sum of the weighting coefficients for a given emitter, which ensure the formation of the main beam with a maximum oriented in the direction u ₀ ± Δu for the first and second rays, respectively, and two MDs, ensuring the formation in each ray of two zeros in the directions of u _p and 2u ₀ -u _p respectively. In this case, the weights of compensating MDs are chosen different.

 The disadvantage of this method is the need to change the complex weighting coefficients (i.e., amplitudes and phases) in all 2N devices for complex weighing of the channels of beam formation of a single-pulse group.

 The proposed method is aimed at eliminating the identified shortcomings of the known methods and allows you to form zeros in the total and differential BP of a monopulse phased AR with separate beam formation when the weight coefficients in the part of the complex weighing devices change, and also eliminates the RSN bias.

 The structural diagram of a device operating by the proposed method is presented in figure 1. Figure 2 and figure 3 illustrate an example of the formation of zeros in the total and differential MD MAP, respectively.

 Consider the essence of the proposed method. As in [1], two sublattices of P-elements in each are distinguished in the initial AR.

Further, as in the prototype [2], the signals received by each emitter are divided into two channels, summed the signals from the outputs of the same name with the dividers, with their weight coefficients, and form the total and differential DN. However, unlike the prototype, the weighting coefficients of the signals received by 2P elements of adaptive sublattices are selected from the condition that the first and second beams of the monopulse group are equal to zero in the P interference directions u _p ^p (p = 1,2, ..., P) and in P symmetric they according to the generalized coordinate with respect to the RSN directions 2u ₀ -u _p ^p , and the weighting coefficients (i.e. phases, since a phased monopulse AR is considered) of the signals in the N-2P elementary signals are chosen equal to their values corresponding to a given or initial distribution.

Thus, since each beam of the monopulse lattice contains zeros in the directions u _p ^p and 2u ₀ -u _p ^p, respectively, zeros in these directions are formed both in the total and in the difference MD.

The above comparative analysis of the claimed method and prototype shows that the claimed one differs in that the conditions for performing the weighing operation are changed: the weight coefficients of the signals received by each emitter from adaptive sublattices are selected from the condition that the first and second beams of the monopulse lattice are equal to zero in the P interference directions u _p ^p and in p symmetrical to them by the generalized coordinate directions relative PCH 2u ₀ -u _n ^p, and the weighting coefficients (phase) signals received by the other N-2P elements leave their equal znach niyama corresponding to a predetermined or initial distribution.

 Consider the proposed method on the example of the formation of one zero.

где f_n(u) - парциальная ДН излучающей системы при возбуждении n-го элемента (n=1,2,...,N) волной единичной амплитуды и нулевой фазы;
j(^1,2) - комплексные весовые коэффициенты в каналах формирования лучей;

- обобщенная угловая координата;
N и x₀ - число излучателей и шаг решетки;
λ и θ - длина волны и угол, отсчитываемый от нормали к раскрыву.The first and second rays of the monopulse group can be represented as follows:

where f _n (u) is the partial MD of the radiating system upon excitation of the nth element (n = 1,2, ..., N) with a wave of unit amplitude and zero phase;
j ( ^1,2 ) - complex weights in the channels of the formation of rays;

- generalized angular coordinate;
N and x ₀ - the number of emitters and the pitch of the grating;
λ and θ - wavelength and angle, measured from the normal to the opening.

где u_п = u при Θ = Θ_п, Θ_п - направление формируемого нуля.In the direction of u _p, these DNs have values

where u _p = u for Θ = Θ _p , Θ _p is the direction of the formed zero.

где u₀ = u при Θ = Θ₀, Θ₀ - равносигнальное направление.In order to eliminate RSN displacement during the formation of zeros, it is necessary to form an additional zero of the DN, which is symmetric to the first in the generalized coordinate relative to the RSN, i.e. in the direction of 2u ₀ -u _p . Then, in this direction, the DNs of the first and second rays have values

where u ₀ = u for Θ = Θ ₀ , Θ ₀ is the equal-signal direction.

и

В (7) и (8) учтено, что амплитудное распределение в неадаптируемых элементах ФАР может быть неравномерным, в связи с чем в правые части (7) и (8) введены |J $\genfrac{}{}{0ex}{}{\text{(1,2)}}{\text{n}}$ |.
В матричной форме (7) и (8) принимают вид

где [F] квадратная матрица, порядок которой определяется числом формируемых нулей

- 2P мерные векторы с элементами

Неизвестные комплексные весовые коэффициенты J₁ ⁽¹⁾, J_N ⁽¹⁾, J₁ ⁽²⁾ и J_N ⁽²⁾, обеспечивающие формирование нулей в каждом из лучей моноимпульсной группы в направлениях u_п и 2u₀-u_п, определяются из решения систем линейных уравнений (9), т.е.To form two zeros in each of the rays (f ⁽¹⁾ (u) and f ⁽²⁾ (u)), one element is selected at the edges of the MAP, for example, the 1st and Nth elements. Then, taking into account (3-6) and the conditions f ⁽¹⁾ (u _p ), f ⁽²⁾ (u _p ) = 0, as well as f ⁽¹⁾ (2u ₀ -u _p ), f ⁽²⁾ ( 2u ₀ -u _p ) = 0 for the first and second rays of the monopulse group we obtain two systems of linear algebraic equations for unknown complex weighting coefficients

and

In (7) and (8), it was taken into account that the amplitude distribution in non-adaptable elements of the PAR can be uneven, and therefore | J are introduced in the right-hand sides of (7) and (8) $\genfrac{}{}{0ex}{}{\text{(1,2)}}{\text{n}}$ |.
In matrix form, (7) and (8) take the form

where [F] is a square matrix whose order is determined by the number of generated zeros

- 2P dimensional vectors with elements

The unknown complex weighting factors J ₁ ⁽¹⁾ , J _N ⁽¹⁾ , J ₁ ⁽²⁾ and J _N ⁽²⁾ , which ensure the formation of zeros in each of the beams of the monopulse group in the directions of u _p and 2u ₀ -u _p , are determined from solving systems of linear equations (9), i.e.

Необходимо отметить, что порядок систем линейных алгебраических уравнений ограничивается числом формируемых нулей, что является достоинством предлагаемого способа.

It should be noted that the order of systems of linear algebraic equations is limited by the number of generated zeros, which is the advantage of the proposed method.

 Similarly, several zeros can be formed.

The operation of the device operating according to the proposed method can be illustrated using figure 1. The signals received by each emitter 1 are fed to the inputs of the dividers 2 in two directions. The signals from the outputs of the same name dividers are fed to the inputs of the complex weighing devices 3 and 4, respectively, providing multiplication of the signals received by the elements of the sublattices, by weight coefficients (12). The signals received by the remaining N-2P elements are phased using phase shifters 5 and 6, respectively, according to a linear or more complex law. From the outputs of the complex weighing devices, the signals are sent to the corresponding high-frequency adders 7 and 8. The result of the summation in devices 7 and 8 are two beams of the monopulse group, shifted from PCN by ± Δu, respectively, having zeros in the direction of the noise u _p , and also in the mirror symmetrical to it with respect to PCH (2u ₀ -u _p ). From the outputs of adders 7 and 8, the signals corresponding to the beams of the monopulse group are fed to the inputs of the sum-difference converter (for example, a double T-bridge), at the outputs 10 and 11 of which the difference f ^Δ (u) and the total f ^Σ (u) DN are formed . Since each beam of the monopulse group has zeros in the direction of the noise, then zeros in this direction are formed both in the total and in the difference pattern.

Figure 2 shows the first (continuous line) and second (dashed line) rays of a monopulse group with synthesized zeros in the directions u _p (25 ^o ) and 2u ₀ -u _p (-4.3 ^o ), at Θ _o = 10 ^° . Figure 3 shows the total (continuous line) and differential (dashed line) MD MAP with zeros in these directions.

 Thus, the proposed method of generating zeros allows us to generate zeros in the directions of interference in both the total and difference MD of single-pulse headlamps with separate beam formation by adjusting the complex current amplitudes in the elements of adaptive sublattices highlighted at the edges of the headlamps, and to eliminate RSN bias. This allows you to significantly improve the accuracy of direction finding of objects in conditions of active electronic countermeasures.

SOURCES OF INFORMATION
1. Patent 2123743 of the Russian Federation. The method of forming a zero radiation pattern of a phased antenna array. / Manuilov B.D., Bashly P.N., Gladushenko C.G.// B.I. 1998.35.

 2. Patent 2133529 of the Russian Federation. The method of separate formation of zero in the total and difference MD of a monopulse antenna array. / Manuilov B.D., Bashly P.N.// B.I. 1999.20.

Claims (1)

A method of separately forming zeros in the total and difference radiation patterns of a monopulse phased antenna array, which consists in dividing the signals received by each emitter into two channels, summing the signals from the outputs of the same name with phases, which ensure the formation of two beams of the monopulse group deviated from the equal signal direction in the generalized coordinate ^± Δu, where Δu is the distance of the maximums of the rays to the equal-signal direction, and in the subsequent formation of the total and difference diagram directional amm, characterized in that at the edges of the N-element phased antenna array there are two adaptive P-element sublattices, the output signals of which are weighed using complex weighing devices, and the complex weight coefficients of the adaptive sublattices are selected from the condition that the first and second beams of the monopulse group are equal to zero in P directions of interference u _p ^p (p = 1,2, ..., P) and in P symmetric to them in the generalized coordinate with respect to the equal-signal direction uo to directions 2u ₀ -u _p ^p .

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