RU2048699C1 - Phased array of reflector type - Google Patents

Abstract

FIELD: radiolocation. SUBSTANCE: phased array of reflector type is meant for radar systems with electric scanning of beam. It is composed of three sublattices of rhombic shape, radiators of circular polarization, control cell and three special computers. Aperture of array is manufactured in the form of regular polygon. Each sublattice consists of N columns and M+1 lines located at angle 120 deg relative to each other. Each control cell is fabricated in the form of parallelogram and includes bars of phase inverters and printed circuit boards. EFFECT: increased precision of setting of phase distribution, enhanced gain factor and reduced time of switching over of beam of phase array. 4 dwg

Description

 The invention relates to antenna-feeder devices and can be used in radar systems with electric beam scanning.

 It is known that in antennas with electric beam scanning, one of the main problems is associated with the creation of the required phase distribution on all elements of the array. Having received the initial information about the required angular position of the beam in a given sector of space, it is necessary to calculate the required phases of the antenna array emitters in the special computer and to set the phases in the phase shifters of the PAR.

 Headlights such as Patriot, Missile Site Radar (MSR) and PAR are multifunctional radar systems that can be effectively used in aerodrome systems for visibility and blind landing, as well as for the detection and tracking of aircraft. The phased array radar consists of several thousand phase shifters.

 Managing them is challenging.

 In order to increase the gain of the PAR, and reduce its cost, it is advisable to use the principle of modular construction. The headlamp module includes transceiver equipment, an antenna, and control elements. For beam scanning in a fairly wide sector of angles, the antenna of the PAR module should be a scanning antenna array, and to obtain the minimum gaps between the PAR modules, their aperture should be made in the form of regular hexagons.

 HEADLIGHTS are known in which the elements of the antenna array do not form a rectangular, but a triangular (hexagonal) grid. Obviously, in such cases, the design of the PAR, including the phase shifter control system associated with a rectangular coordinate system, is not always the most efficient.

 In particular, for a hexagonal lattice, an oblique coordinate system may be more suitable in the formation of a control algorithm.

 The closest in technical essence and the achieved result is a phased antenna array of a reflective type with an aperture in the form of a regular hexagon, excited by a spatial power distributor by an irradiator having axial symmetry, containing circularly polarized radiators located in the nodes of the hexagonal grid and connected to the special calculator of the PAR beam cell control, each of which is made in the form of a line of phase shifters with a printed circuit board.

 This device can be used as a stand-alone phased array and as part of a large-aperture antenna module of the phased array.

 Known variants of the design of the HEADLIGHTS made on the basis of individual radiating elements and on the basis of integrated elements. In the latter case, the headlamp emitters are grouped into 4 elements with a line of phase shifters and a control board.

 The disadvantage of the prototype device is that with a significant number of elements of the PAR module (of the order of several thousand emitters), even in the case of using integrated elements of 4 emitters, it is necessary to use an extremely large number of conductors connecting the phase shifters to the special calculator of the module. This leads to the interconnection of the control circuits, distortion of the control pulses and phase relations in the phase shifters, and this entails a decrease in the gain of the PAR.

 In addition, the specified implementation of the phased array requires the use of a complex control algorithm, which reduces the speed of beam switching in a given sector of space.

 In addition, it is difficult to remove heat generated from the PAR elements due to control energy and due to microwave losses. This leads to uneven heating of the elements within the PAR aperture. This factor is especially critical in the case of using ferrite phase shifters, the phase of which substantially depends on the ambient temperature. Ultimately, this also causes a decrease in the accuracy of setting the phase distribution in the aperture of the antenna and the gain of the PAR.

 The aim of the invention is to improve the accuracy of the installation of the phase distribution, increase the gain (gain) and reduce the switching time of the beam HEADLIGHT.

+Ψ_i где k₁, k₂, k₃ коды фазовых набегов по осям х, y, z, ориентированным под углом 120^о относительно друг друга;
x_i, y_i, z_i координаты излучателя; λ длина волны;
Н высота фокального кольца облучателя над апертурой ФАР;
r_o радиус фокального кольца облучателя;
R_i радиус-вектор излучателя;
Ψ _i начальная фазовая длина i-го фазовращателя.This is achieved by the fact that in a phased antenna array of a reflective type with an aperture in the form of a regular hexagon excited by a spatial power distributor-irradiator having axial symmetry containing circularly polarized emitters located in the nodes of the hexagonal grid and connected to the special calculator of the PAR control beam, control cells, each of which is made in the form of a line of phase shifters with a printed circuit board, the aperture of the antenna array is made in the form of three identical rum sublattices matic form of columns and N _o N _o +1 rows disposed at an angle ¹²⁰ to each other, in each control cell, wherein the aperture is formed as a parallelogram with sides oriented along the rows and columns sublattice additionally introduced parallel-arranged phase shifters ruler and control boards, and two special calculators identical to the first one are additionally introduced into the beam control system, with each special calculator connected to control cells of the corresponding sublattice, and phase shifts introduced from each special calculating a respective phase shifters sublattice are defined by the formula:
φ _i = k ₁ x _i + k ₂ y _i + k ₃ z _i +

+ Ψ _i where k _1, k _2, k ₃ codes of phase shifts along the axes x, y, z, oriented at an angle ^of 120 relative to each other;
x _i , y _i , z _i coordinates of the emitter; λ wavelength;
H the height of the focal ring of the irradiator over the aperture of the PAR;
r _{o the} radius of the focal ring of the irradiator;
R _{i is the} radius vector of the emitter;
Ψ _{i is the} initial phase length of the ith phase shifter.

 In FIG. 1 shows a General view of the headlamp, namely the antenna module.

 The proposed module contains a spatial power distributor (feed) 1, a waveguide path 2, control cells 3, 4, a radiotransparent shelter 5, a building 6, radiators 7, a thermal stabilization (heat exchange) system with air ducts 8. Each of the control cells 3, 4 contains printed circuit boards 9 and the line of phase shifters 11.

 In FIG. 2 shows the aperture of the antenna module, divided into 3 sublattices 10 (A, B, C), in each of which the boundaries of the control cells are indicated. The numbering of rows and columns in each sublattice 10 and the directions of the oblique axes of the x, y, z coordinates are indicated.

In an antenna array with an aperture in the form of a regular hexagon, the number of emitters 7 located at the nodes of the hexagonal grid (a special case of a triangular grid with a PAR cell in the form of an equilateral triangle) is (excluding the central element)
3N _o (N _o + 1), where N _{o is} an integer.

It follows that the number of emitters in each sublattice 10, occupying 1/3 of the aperture area, is N _o (N _o + 1). Therefore, in the claimed solution, the number of rows N _o + 1 elements of the sublattice 10 per unit exceeds the number of columns N _o regardless of the total number of emitters in the module.

 In FIG. Figure 3 shows the antenna array of 18 radiating elements 7. It can be seen that in this case the number of columns is 2 and the number of rows is 3. The free central region of the module aperture is used to fasten the power distributor 1 (irradiator) and connect a supply waveguide to it.

With a significant number of emitters (the total number of emitters in the module N is several thousand, the number of columns in the sublattice is N _o ≥ 30), the aperture of the rhombus-shaped sublattice is densely filled with radiating elements.

 The sizes of control cells are selected based on the most rational filling of the aperture of the sublattice 10 with a minimum number of sizes, as well as taking into account the technological features of their manufacture and the need to reduce the number of connecting conductors. As can be seen from FIG. 2, for dense filling of the aperture of the module, two standard sizes of control cells 3, 4 are sufficient.

 The control of the phase shifters in the proposed device is elementwise. The calculation of the phase relations in the special calculator takes into account the hexagonal symmetry of the emitters and is carried out along the rows and columns. The wiring of control circuits is made along the lines.

+Ψ_i где к₁, к₂, к₃ коды фазовых набегов по осям модуля соответственно;
x_i, y_i, z_i координаты излучателя-фазовращателя в модуле;
Н высота облучателей над апертурой модуля;
r_o радиус фокального кольца;
R_i радиус вектор излучателя;
Ψ _i начальная фазовая длина i-го фазовращателя.Scanning in the module is carried out by creating the required phase distribution in the module aperture. The phase values in the module aperture are calculated when approximating geometric optics, taking into account the fact that the beam structure of the field of the irradiator 1 forms a focal ring according to the following formula:
φ _i = k ₁ x _i + k ₂ y _i + k ₃ z _i +

+ Ψ _i where k ₁ , k ₂ , k ₃ are phase raid codes along the module axes, respectively;
x _i , y _i , z _i coordinates of the emitter-phase shifter in the module;
N the height of the irradiators above the aperture of the module;
r _{o the} radius of the focal ring;
R _{i is the} radius of the emitter vector;
Ψ _{i is the} initial phase length of the ith phase shifter.

The coordinates x _i , y _i , z _{i are} normalized to the lattice step and take the values: x _i x _i '/ d; y _i y _i '/ d; z _i z _i '/ d.

d sinθ·cosφ
K₂=

d(sinθ·cosφ+

sinθ·sinφ)
K₃=

d(-sinθ·cosφ+

sinθ·sinφ) где λ длина волны;
d шаг решетки.When calculating the phases in the module aperture, the values of K ₁ , K ₂ and K _{3 are} determined by the given angular spherical coordinates θ and φ of the beam position:
K ₁ =

d sinθ cosφ
K ₂ =

d (sinθ cosφ +

sinθ
K ₃ =

d (-sinθ cosφ +

sinθ · sinφ) where λ is the wavelength;
d grid step.

 In the special calculator, the required phases are determined in the form of phase state codes.

For each sublattice, only two of the indicated phase incursions are used. So for sublattice A (see Fig. 2), phase incursions K ₂ and K ₃ are calculated along the y and z coordinates, and the value of K _{1 is} assumed to be zero, for sublattice B, respectively, K ₂ 0, and for sublattice C-K ₃ 0.

When the beam is oriented normal to the aperture of the lattice, K ₁ K ₂ K ₃ 0.

 In order to eliminate phase errors of collimation in the module aperture, it is necessary to introduce nonlinear phase corrections into each phase shifter of the PAR. This is taken into account in the calculation formula by the square root term of the quantity determined by the geometry of the lattice.

The last term (Ψ _i ) serves to compensate for the phases due to technological tolerances for the manufacture of phase shifters.

 Thus, in the proposed device, a combination of the advantage in the accuracy of setting the phase relations inherent in the element-wise beam control method is achieved with the advantages of the row-column control method in terms of the simplicity of the control algorithm and the design of control circuits.

 Compared with the prototype, each special calculator controls only 1/3 of the total number of phase shifters in the antenna array, which allows to simplify its design.

The time for entering information into the phase shifters of the PAR module is three times less than in the case of a grating with elementwise control and the same number of phase shifters. This is due to the fact that the aperture of the module is divided into three identical sublattices of a rhombic shape, where information on phase states is simultaneously recorded. The time for entering information is determined by the following formula:
T τ x [N / 3 (N _o +1)] where τ is the time of entering information into one column of phase shifters;
N is the total number of phase shifters in the PAR module;
N _o + 1 is the number of phase shifters in one column.

 The air temperature stabilization system 8 contains air ducts parallel to the side faces of each sublattice 10 and creates parallel air flows between the printed circuit boards 9 of the control cells 3, 4.

 The hexagonal shape of the module aperture provides hexagonal packing of the modules on the frame of the modular PAR, which allows you to increase the number of modules (see Fig. 4) and minimize the gaps between the modules.

 An example of a specific implementation of the phased antenna array of the PAR module can be a device whose design is shown in FIG. 1 and 2. The antenna array of the module has 3600 emitters and phase shifters, grouped into 36 control cells (each sublattice contains 1200 emitters and phase shifters, 12 control cells, respectively). In each control cell there are 6 lines of phase shifters. From a special computer to each sublattice, a bundle of 250 conductors is laid.

 In a prototype device with the same number of phase shifters integrated over 4 elements, an order of magnitude larger number of conductors would be required to connect the antenna array to a special calculator.

 According to the assessment, the gain in the antenna array gain in comparison with the prototype device is due to an increase in the accuracy of setting the phase distribution to 1 dB.

Claims (1)

A PHASED ANTENNA ARRAY OF REFLECTIVE TYPE containing an irradiator located along the central axis of the lattice, the aperture of which is made in the form of a regular hexagon, in the nodes of the hexagonal grid of which there are circularly polarized radiators, control cells, the outputs of which are connected to the inputs of the control unit, the outputs of which are connected to the inputs of the unit control beam containing the first special calculator, with each control cell consists of a line of phase shifters and a printed circuit board, characterized in that the aperture array antenna is in the form of three identical sublattices rhombic shape, each of which consists of N _of columns and N _a + 1 rows disposed at an angle of 120 ^o to each other, in each control cell, the aperture which is formed as a parallelogram with sides oriented along the rows and columns of the corresponding sublattice, parallel lines of phase shifters and a control board are introduced, and two special computers identical to the first are introduced into the beam control unit, with each special computer connected to the outputs of the control cells of the corresponding sublattice and is configured to generate phase shifts for phase shifters of the corresponding sublattice in accordance with the expression
φ _i = k ₁ · x _i + k ₂ y _i + k ₃ z _i +

where K ₁ , K ₂ , K ₃ codes of phase incursions in columns and rows for the corresponding sublattice;
λ wavelength;
x _i , y _i , z _i coordinates of the emitter of circular polarization;
H the height of the focal ring of the irradiator over the aperture of the PAR;
r _{about the} radius of the focal ring of the irradiator;
R _{i the} radius vector of the emitter of circular polarization;
j _{i is the} initial phase length of the i-th phase shifter.

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