RU2579610C2 - Phase method of nulling beam pattern of planar phased antenna array - Google Patents

Abstract

FIELD: radio engineering and communications.

SUBSTANCE: invention relates to antenna engineering. Method of forming nulling pattern (NP) in flat phased antenna array (PAA) involves estimating the level of the initial directional pattern of N-element PAA, selecting in the aperture two M-element sub-arrays and making phase adjustments, with a minus sign for elements of one sub-array and with a plus sign for elements of another sub-array. For formation of caving in NP flat phased antenna array in several directions assessment of initial directional pattern of N-element PAA is carried out in to preset directions, which specify two angular coordinates θ_{dir i} and φ_{dir i}, is selected to equivalent linear openings, angles of which are equal to values of coordinates to the directions φ_{dir i}, the excitation of these openings, after extraction in each equivalent linear aperture two M-element sub-arrays arranged on its edges, their phase adjustments are selected equal to absolute value from the condition of preset depth, width and coordinates θ_{dir. i} failure. Phase adjustments, calculated for formation of failures, the elements of phased antenna array, forming the equivalent linear aperture, provided that M-element sub-arrays K equivalent linear openings mismatched PAA elements are formed, where θ_{dir i} and φ_{dir i} -given direction in the spherical coordinate system, and θ_{dir. i} is counted from the normal to plane of the aperture PAA; i is serial number and i = 1…K; K is the number of preset directions.

EFFECT: technical result consists in formation caving in NP flat PAA in several directions with angular coordinates in spherical pre-setting system.

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Description

The invention relates to antenna technology and can be used to solve the problem of the formation of dips in the radiation patterns (LH) of flat phased antenna arrays (PAR) by changing only the phases of the excitations of its elements.

The known method [El-Azhary, M.S. Afifi, and P.S. Excel, A simple algorithm for sidelobe cancellation in a partially adaptive linear array, / IEEE Transactions on Antennas and Propagation, vol. Ap-36, No.10, October 1988, pp.1484-1486], in which the extreme elements of the lattice are used to form an extended region of suppression of the side lobes of the MD of the linear PAR. The essence of this method is that the signals passing through the extreme elements receive phase shifts equal in magnitude but opposite in sign. The maximum of the DN formed by the extreme elements is shifted so that it coincides with the direction of the maximum of the suppressed side lobe, the angular range of which covers the direction of arrival of the interference signal. In this case, the amplitude component of the additional pattern is multiplied by a constant so that the additional pattern has the same amplitude as the suppressed side lobe of the pattern of the entire grating. The phase component of the additional DN in the region of the suppressed side lobe should differ by 180 ° from the phase component of the suppressed side lobe of the DN of the entire lattice.

Closest to the technical nature of the proposed method is the "Method of forming a zero radiation pattern of a phased antenna array" [RU 2123743 C1, publ. 12.20.1998], based on the assessment of the level of the non-standardized initial radiation pattern of the N-element headlamp in the direction of interference f (θ _n ), the allocation of two adaptive M-element sublattices located at the edges of the original, taking into account the condition 2M≥f (θ _n ), and introducing phase corrections into the elements of adaptive sublattices, moreover, phase corrections for the mth pair of emitters from the edge (m = 1,2, ... M) are selected in accordance with the relation

Where:

λ, x ₀ — wavelength and lattice pitch;

θ is the angle measured from the normal to the opening;

θ ₀ , θ _p - the direction of the main maximum and interference, respectively. The minus sign in the ratio corresponds to the elements of the left adaptive sublattice, and the plus sign corresponds to the right.

The disadvantage of both known methods is that they cannot be used to form several dips.

The technical result of the proposed method is the formation of dips in the bottom of a flat headlamp in several predetermined directions, having angular coordinates in a spherical coordinate system (θ _{eg i} , φ _{eg i} ), and the phases of the signals passing through the extreme elements of the equivalent linear aperture of this headlamp are changed to a constant value, which allows to simplify and accelerate the process of formation of several dips.

The essence of the proposed phase method for the formation of dips in the bottom of a flat headlamp consists in assessing the level of the initial radiation pattern of the N-element headlamp, highlighting two M-element sublattices in the aperture and introducing phase corrections, with a minus sign for elements of one sublattice and plus sign for elements of another sublattice .

New in the claimed invention is that the assessment of the level of the initial radiation pattern of the N-element headlamp is carried out in K predetermined directions, which are given by two angular coordinates θ _{eg I} and φ _{eg i} , choose K equivalent linear openings whose angles are equal to the coordinates of the directions K of directions φ _{eg I,} calculated excitation of these apertures, after separation of each equivalent linear aperture two M-element sublattice disposed at its edges, the magnitude of the phase correction is selected equal to the absolute zna eniyu of conditions specified depth, width and coordinates θ _{eg i} failure, phase FAS elements constituting the M-element sublattice K equivalent linear apertures, changing the amount of phase correction of the sublattices, provided that the M-element sublattice K equivalent linear apertures formed mismatched elements PAR, where θ _{ex i} and φ _{ex i} are the specified directions in the spherical coordinate system, and θ _{ex i} , is counted from the normal to the opening plane of the PAR; i - serial number of a given direction, i = 1 ... K; To - the number of specified directions.

Figure 1 shows an example of a flat headlamp with options for forming equivalent linear openings at K = 3, where K is the number of specified directions equal to the number of equivalent linear openings; i - serial number of a given direction and the corresponding equivalent linear aperture, i = 1 ... K; φ _{ex 1, 2, 3} are the angles of equivalent linear openings, M is the number of elements in the sublattices of equivalent linear openings.

Figure 2 shows:

a) - PAR with an elliptical shape of the aperture, on which N = 1458 elements with a uniform phase distribution are located;

b) - spatial daylight. Hereinafter, the spatial PD headlights are given in the coordinates of the guiding cosines u, v, where u = sin (θ) cos (φ), v = sin (θ) sin (φ), sections are shown by straight lines;

c) - PD headlamps in the azimuthal section (φ = 0 °). Hereinafter, unless otherwise indicated, when displaying the pattern in any section along the abscissa, the variable θ in degrees is plotted;

g) - PD headlamps in elevation section (φ = 90 °).

Figure 3 shows an example of the formation of two dips in orthogonal sections of the headlight beam, where

a) - opening the PAR with a phase distribution modified in accordance with two equivalent linear openings, whose angles are φ _{ex 1} = 0 ° and φ _{ex 2} = 90 °, numbered areas show elements with altered phases to form dips with corresponding numbers;

b) the spatial pattern, the coordinates of the centers of the dips: θ _{ex 1} ≈6 °, φ _{ex 1} = 0 ° (u _{ex 1} = 0.105, v _{ex 1} = 0), θ _{ex 2} ≈16 °, φ _{ex 2} = 90 ° (u _{ex 2} = 0, v _{ex 2} = 0.276), hereinafter: the centers of the circles indicate the centers of the dips;

c) - MD in the section, the angle of which is equal to the coordinate value, _{eg, 1} = 0 ° for headlamps with a changed phase distribution (thick line), hereinafter: light paths in this section for headlamps with a uniform phase distribution are shown by a thin line, the arrow indicates the direction center of failure in this section;

g) - MD in the section, the angle of which is equal to the coordinate value φ _{ex 2} = 90 °.

Figure 4 shows an example of the formation of two dips in non-orthogonal sections of the headlight beam, where

a) - opening the PAR with a phase distribution modified in accordance with two equivalent linear openings, the angles of which are equal to φ _{ex 1} = 0 ° and φ _{ex 2} = 60 °;

b) - spatial DN, coordinates of the centers of the dips: θ _{ex 1} ≈6 °, φ _{ex 1} = 0 ° (u _{ex 1} = 0.105, v _{ex 1} = 0), θ _{ex 2} ≈15 °, φ _{ex 2} = 60 ° (u _{e.g. 2} = 0.129, v _{e.g. 2} = 0.226);

c) - MD in the section, the angle of which is equal to the value of the coordinate φ _{ex 1} = 0 °;

g) - MD in the section, the angle of which is equal to the coordinate value φ _{ex 2} = 60 °

Figure 5 shows an example of the formation of three dips in the daylight, where

a) - opening the headlamp with a phase distribution modified in accordance with three equivalent linear openings, whose angles are φ _{ex 1} = 0 °, φ _{ex 2} = 45 °, φ _{ex 3} = 90 °, numbered areas show elements with altered phases for formation of dips with corresponding numbers;

b) - Nam spatial coordinates dips centers: θ _{example 1} ≈14 °, φ = 0 _{eg 1} ° (u _{eg 1} = 0.242, v = 0 _{1, for example),} θ _{eg 2} ≈25 °, φ = 45 _{eg 2} ° (u _{e.g. 2} = 0.299, v _{e.g. 2} = 0.299); φ _{ex 3} = 90 ° (u _{ex 3} = 0, v _{ex 3} = 0.309);

c) - MD in the section, the angle of which is equal to the value of the coordinate φ _{ex 1} = 0 °;

g) - MD in the section, the angle of which is equal to the value of the coordinate φ _{ex 2} = 45 °;

d) - DN in the section, the angle of which is equal to the coordinate value φ _{ex 2} = 90 °.

Figure 6 shows an example of the formation of two dips in orthogonal sections of the headlight beam during scanning, where

a) - spatial pattern, coordinates of the centers of the dips: θ _{ex 1} ≈6 °, φ _{ex 1} = 0 ° (u _{ex 1} = 0.105, v _{ex 1} = 0), θ _{ex 2} ≈15 °, φ _{ex 2} = 90 ° (u _{e.g. 2} = 0, v _{e.g. 2} = 0.259);

b) - the same spatial pattern, but after scanning at an angle θ ₁ = 30 °, φ ₁ = 0 ° ( u ₁ = 0.5, v ₁ = 0);

c) - MD in the section v = 0, the variable and is plotted on the abscissa axis;

d) - MD in the cross section u = 0.5, the variable v is plotted along the abscissa.

A characteristic feature of this method is the immutability of the excitation of the main part of the PAR elements, since the excitation changes only for those PAR elements that form the extreme elements of the equivalent linear openings. In this case, the angular position of the centers of the dips relative to the beam of the beam in the coordinate system of the guiding cosines (and, v) and the amount of suppression in the center of each hole are saved during scanning.

Figure 2a shows a headlamp having an elliptical opening, on which N = 1458 elements are located. In the aperture of the PAR, an amplitude distribution falling to the edges with an instrumentation of ≈0.9 was created. Fig.2b, c, d shows the spatial daylight of the headlight and the headway in the main - azimuthal and elevation - sections. The initial level of the maximum side lobes of the MD with an in-phase distribution is ≈-28dB.

Using the proposed method, it is possible to simultaneously form several (K) dips in the cross sections of the MD, the angles of which are equal to the coordinate values φ _{ex i} . For this excitation K calculated corresponding equivalent linear apertures (1) and DN each formed in the direction of dip θ _{eg i} - phase corrections computed for the formation of dips on the elements making FAS forming the equivalent linear aperture. This is illustrated by the example of the formation of 2 dips (K = 2) in orthogonal sections (Figa-g). On figa it is seen that the sublattices of the equivalent linear openings form mismatched elements of the opening of the PAR. In the equivalent linear one, which ensures the formation of a dip in the direction f = i (θ _{e.g. 1} ≈6 °), the number of elements in each of the two sublattices M = 9, in the equivalent linear opening (i = 2, θ _{e.g. 2} ≈16 °) -M = 3. In this example, the decrease in lateral radiation at the center of each dip was more than 16dB. The magnitude of the rise in lateral radiation from opposite sides of the beam and the formed dip of the sides was ≈5-7 dB. The decrease in the beam level of the headlamp is approximately 0.12 dB.

Dips can form not only in orthogonal, but also in other sections, provided that the sublattices of equivalent linear openings are formed by mismatched PAR elements. An example of the formation of two dips (K = 2) in the azimuthal section (φ _{ex 1} = 0 °) and a section with an angle φ _{ex 2} = 60 ° is shown in Fig.4a-d. The case of the formation of dips in three sections (K = 3) is presented in Fig.5a-d. The constancy of the angular positions of the centers of the dips relative to the beam of the beam and the amount of suppression in the center of each failure during scanning is confirmed by Figa-g.

The proposed method provides for the formation of several dips in the bottom of a flat headlamp in several predetermined directions, having angular coordinates (θ _{ex i} , φ _{ex i} ) in a spherical coordinate system. In addition, the phases of the signals passing through the extreme elements of the equivalent linear aperture of this headlamp are changed by a constant value, which makes it possible to simplify and accelerate the process of formation of dips.

Claims (1)

The phase method of forming dips in the directivity pattern of a flat phased antenna array (PAR), based on the assessment of the level of the initial radiation pattern of the N-element PAR, highlighting two M-element sublattices in the aperture and introducing phase corrections, with a minus sign for elements of one sublattice and with a sign plus elements other sublattice, characterized in that the initial estimate of the level diagram directivity N-element phased arrays K is carried out in predetermined directions that define two angular coordinates θ _{nap i} and φ _{eg i,} selected to equivalent linear apertures, angles which are equal to the values of the coordinates to the direction φ _{eg i,} calculate the excitation of these apertures, after separation of each equivalent linear aperture two M-element sublattice disposed at its edges, the magnitude of the phase correction is selected equal to the absolute value of conditions specified depth, width and coordinates θ _{i voltage} failure, phase corrections computed for the formation of dips, contribute to FAS elements constituting the equivalent linear aperture, When the proviso that M-element sublattice K equivalent linear apertures formed mismatched elements PAR where
θ _{for example i} and φ _{for example i} are given directions in the spherical coordinate system, and θ _{for example i is} measured from the normal to the aperture plane of the PAR;
i - serial number of a given direction, i = 1 ... K;
To - the number of specified directions.

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