CN113690616B - Liquid crystal array antenna beam forming and controlling method based on phase decomposition - Google Patents
Liquid crystal array antenna beam forming and controlling method based on phase decomposition Download PDFInfo
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- CN113690616B CN113690616B CN202010417188.5A CN202010417188A CN113690616B CN 113690616 B CN113690616 B CN 113690616B CN 202010417188 A CN202010417188 A CN 202010417188A CN 113690616 B CN113690616 B CN 113690616B
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- 239000004973 liquid crystal related substance Substances 0.000 title claims abstract description 63
- 238000000354 decomposition reaction Methods 0.000 title claims abstract description 47
- 238000000034 method Methods 0.000 title claims abstract description 26
- 230000005855 radiation Effects 0.000 claims abstract description 27
- 230000005684 electric field Effects 0.000 claims description 9
- 239000000463 material Substances 0.000 claims description 6
- 230000008859 change Effects 0.000 claims description 3
- 230000003044 adaptive effect Effects 0.000 claims 3
- 238000010586 diagram Methods 0.000 description 23
- 230000003287 optical effect Effects 0.000 description 10
- 230000001276 controlling effect Effects 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 4
- 230000005672 electromagnetic field Effects 0.000 description 4
- 230000001105 regulatory effect Effects 0.000 description 4
- 238000003786 synthesis reaction Methods 0.000 description 4
- 230000009471 action Effects 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
- H01Q3/26—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture
- H01Q3/2605—Array of radiating elements provided with a feedback control over the element weights, e.g. adaptive arrays
- H01Q3/2652—Self-phasing arrays
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- Variable-Direction Aerials And Aerial Arrays (AREA)
Abstract
The invention relates to the field of communication and algorithms, in particular to a liquid crystal array antenna beam forming and self-adaptive control method based on phase decomposition, which comprises the following steps of S1, giving a radiation pattern function of a desired array antenna; s2, determining the feeding weight vector of each array element by approximating a given pattern functionThe method comprises the steps of carrying out a first treatment on the surface of the S3, for eachPerforming phase decomposition on an array plane, and determining the phase decomposition array element distribution corresponding to the direction of a certain wave beam; s4, realizing array distribution of liquid crystal deflection states in the phase decomposition array elements through a driving system of the antenna so as to realize a desired array antenna radiation pattern. The present invention forms a generalized approach to beam forming and directional control for liquid crystal array antennas and other metamaterial array antennas.
Description
Technical Field
The invention relates to the field of communication and algorithms, in particular to a liquid crystal array antenna beam forming and self-adaptive control method based on phase decomposition.
Background
The traditional phased array antenna adopts a mode of attenuator and phase shifter to realize the control of the amplitude and phase of the radiation field of each antenna unit. Firstly, each radiation unit forms a two-dimensional or three-bit array structure, then a feed weight repetition vector corresponding to each antenna unit is determined according to beam pointing requirements, and the feed weight of each array element is realized by connecting an attenuator and a phase shifter to each radiation unit, so that digital beam forming and pointing scanning of the array antenna are realized.
The metamaterial array antenna including the liquid crystal array antenna can realize digital beam forming and pointing control of the array antenna without an attenuator and a phase shifter. This can reduce the manufacturing cost of the antenna to a great extent. Meanwhile, the metamaterial array antenna including the liquid crystal array antenna has a lower section, smaller volume and lighter weight due to the fact that the attenuator and the phase shifter are not adopted. Therefore, the method has great application prospect in the fields of satellite communication, internet of things, internet of vehicles and 5G millimeter wave communication.
Disclosure of Invention
In the liquid crystal array antenna, for the feed weight repetition vector of an array element corresponding to a certain beam direction, each feed weight repetition vector can be decomposed on two or more liquid crystal units with a certain phase difference by carrying out phase decomposition, the deflection state of liquid crystal in each radiation unit is enabled to be in amplitude by an external electric field, and phase control is realized by the optical path difference between the phase decomposition units, so that the coding of the feed weight repetition vector on the liquid crystal array is realized. For each directional beam, the coding of the feed weight repetition vector is repeated once in the liquid crystal array, so that the directional control of the liquid crystal array antenna is realized.
Based on the background, the invention regulates and controls the deflection state of the liquid crystal in each radiating unit in the liquid crystal array antenna through the moment generated by the sum between the externally applied electric field and the polarized liquid crystal dipole moment, thereby regulating and controlling the amplitude of the electromagnetic field in each radiating unit, realizing the phase control of each liquid crystal unit through the optical path difference between the phase decomposition units, and providing the algorithm of digital wave beam forming and finger self-adaptive direction control of the liquid crystal array antenna on the basis of the regulating and controlling method.
The invention aims to provide a liquid crystal array antenna beam forming and self-adaptive control method based on phase decomposition, which comprises the following steps:
s1, giving a radiation pattern function of a desired array antenna;
s2, determining the feeding weight vector of each array element by approximating a given pattern function；
S3, for eachPerforming phase decomposition on an array plane, and determining the phase decomposition array element distribution corresponding to the direction of a certain wave beam;
s4, realizing array distribution of liquid crystal deflection states in the phase decomposition array elements through a driving system of the antenna so as to realize a desired array antenna radiation pattern.
Optionally, in step S3The magnitude of the components of the array element radiation fields Eij in the x-axis and the y-axis in the two corresponding phase decomposition units is realized by adjusting the deflection degree of the liquid crystal in the phase decomposition array elements.
Alternatively, the adjustment of the degree of deflection of the liquid crystal includes applying an electric field and controlling the change in the magnitude thereof, and polarizing the liquid crystal molecules in the liquid crystal material to different degrees of deflection.
Optionally, step S4 includes determining each of the phase-resolved array elements by applying a voltage driving signal to each of the phase-resolved array elements to achieve an array distribution of liquid crystal deflection states in the phase-resolved array elementsThe corresponding magnitude is the value of the two decomposition units; the desired radiation pattern of the array antenna is achieved by superposition of the radiation field on the phase-resolved array elements in the far field region.
Optionally, in step S4, when the beam direction of the array antenna changes, the control voltage on the corresponding radiation unit in the array antenna is refreshed by the control system of the antenna, so as to realize the switching of the beam direction and achieve the reproduction of the array antenna pattern.
Compared with the prior art, the invention provides a liquid crystal array antenna beam forming and self-adaptive control method based on phase decomposition, which has the following beneficial effects:
the invention regulates and controls the deflection state of the liquid crystal in each radiating unit in the liquid crystal array antenna, thereby regulating and controlling the amplitude of the electromagnetic field in each radiating unit, and realizing the phase control of each liquid crystal unit through the optical path difference between phase decomposition units, thus forming a common method for the beam synthesis and the direction control of the liquid crystal array antenna and other metamaterial array antennas.
Drawings
FIG. 1 is a schematic diagram of array cell distribution and orientation in the xy plane;
FIG. 2 is a schematic diagram of a process of array antenna beam synthesis;
FIG. 3 is an exploded view of an array element radiation vector;
fig. 4 is a schematic diagram of the synthesis of the array element beams after phase decomposition;
FIG. 5 is a schematic diagram showing the deflection of polarized liquid crystal under the action of an external field;
FIG. 6 is a schematic diagram of a rectangular grid rectangular boundary two-dimensional array distribution;
FIG. 7 is a schematic diagram of a rectangular grid circular boundary two-dimensional array distribution;
FIG. 8 is a schematic diagram of a two-dimensional array distribution of hexagonal boundaries of a rectangular grid;
FIG. 9 is a schematic diagram of a triangular grid rectangular boundary two-dimensional array distribution;
FIG. 10 is a schematic diagram of a triangular grid circular boundary two-dimensional array distribution;
FIG. 11 is a schematic diagram of a triangular grid hexagonal boundary two-dimensional array distribution;
FIG. 12 is a schematic distribution diagram of a circular array;
FIG. 13 is a schematic diagram of a concentric circular array distribution;
FIG. 14 is a schematic diagram of a two-dimensional conformal array distribution on a curved surface;
FIG. 15 is a schematic representation of refractive index ellipsoids of uniaxial crystals and their modulation of transmitted electromagnetic waves;
FIG. 16 is a schematic diagram of beam forming and pointing control flow for a liquid crystal array antenna;
fig. 17 is an equal side lobe array antenna pattern with 60 ° pointing achieved by a phase decomposition method.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Examples: as shown in fig. 1, the antenna is assumed to be an array in the xy plane, and the position vector of an array element is ij The director of the beam is +.>The angle between the beam director and the z-axis is +.>Projection of the director on the xy plane with an angle of +.>Thus, the spatial phase factor of the array element radiation pattern can be expressed as
As shown in fig. 2, for an array antenna, the input signal for each array element is represented asThe feed weight vector of each array element is +.>Expressed, under far field approximation, the radiation pattern function S of the array antenna can be expressed as:
wherein,
thus, the feeding weight vector of each array element is determinedMeasuring amountAfter the complex values of (a), the beam forming and pointing of the array antenna can be determined theoretically. Because of->Is complex, so how to implement the feed weights through the antenna elements is critical to the problem. For each array element in the liquid crystal array antenna, its radiation field E ij Decomposing in the manner shown in FIG. 3, each of the axes x and y corresponding to an array element, E, in the liquid crystal array antenna ij Included angle with 0 phase reference axis +.>Is thatIs shown, the component in the x-axis is Ex, and the component in the y-axis is Ey. Thus a +.>Is resolved on two array elements of the liquid crystal array antenna with a certain spacing, the spacing of which depends on the direction of the resultant beam and the angle between the x-axis and the y-axis.
In principle, any angle can be formed between the x-axis and the y-axis, when the angle between the x-axis and the y-axis isThe x-axis can correspond to any half axis of the rectangular coordinate system, and the y-axis corresponds to a phase greater than that of the x-axis>Is provided. Corresponding to the array elements of the liquid crystal array antenna, namely the x-axis and the y-axis respectively correspond to two spaces with quarter wavelength (/ for)>) Is used for decomposing the array elements.
As shown in fig. 4If the array antenna beam is required to be directed atThe array element spacing is d, then is +.>The distance between the two corresponding phase decomposition array elements is +.>The electromagnetic fields radiated by the two phase-resolved array elements synthesize a +.>The corresponding array elements radiate electromagnetic fields. And the choice of the array element position depends on +.>If the included angle between the x-axis and the y-axis is +.>When->The first phase decomposition element is located at the first phase reference point and the other phase decomposition element is located closest to the first phase reference point>Where it is located. When->If the argument of (2) is at the second quadrant, then the x-axis in fig. 3 corresponds to the positive half-axis of the y-axis in the rectangular coordinate system and the y-axis in fig. 3 corresponds to the negative half-axis of the x-axis in the rectangular coordinate system. The distance dx by which the position of the first phase-resolved element is shifted with respect to the 0-phase reference point satisfies the following relationship:
another phase decomposition unit corresponding to the phase decomposition unitThe element is positioned closest to the first phase-resolved elementWhere it is located. />The selection of the x-axis and the y-axis and the selection of the position of the first phase-resolved element are identical with the first one when the argument lies in the third and fourth quadrant>The same method is adopted for selecting the distance between the two corresponding phase decomposition array elements. After the position of the first pair of phase resolved elements is determined, the positions of the other pairs of phase resolved elements are determined by the element spacing d.
Thus, with oneIn the corresponding two phase decomposition units, the phase relation between each other has been determined. The magnitude of the components of the array element radiation field Eij on the x axis and the y axis is realized by adjusting the deflection degree of the liquid crystal in the phase decomposition array element.
As shown in fig. 5, the liquid crystal material used in the liquid crystal array antenna according to the present invention may be polarized by an electric field. Polarized dipole momentpAlong the long axis direction of the liquid crystal molecules, an included angle exists between the polarized dipole moment and the external electric field, so that a rotation moment exists on the liquid crystal molecules, and the liquid crystal molecules can deflect to different degrees when the magnitude of the external electric field changes.
The invention provides an antenna array structure formed by combining radiating elements formed by the method for regulating microwave millimeter waves and the radiating structure based on the liquid crystal, which comprises, but is not limited to, a rectangular grid rectangular boundary two-dimensional array distribution diagram shown in fig. 6, a rectangular grid circular boundary two-dimensional array distribution diagram shown in fig. 7, a rectangular grid hexagonal boundary two-dimensional array distribution diagram shown in fig. 8, a triangular grid rectangular boundary two-dimensional array distribution diagram shown in fig. 9, a triangular grid circular boundary two-dimensional array distribution diagram shown in fig. 10, a triangular grid hexagonal boundary two-dimensional array distribution diagram shown in fig. 11, a circular array distribution diagram shown in fig. 12, a concentric circular array distribution diagram shown in fig. 13, and a two-dimensional conformal array distribution diagram on a curved surface shown in fig. 14.
Fig. 15 shows an ellipsoid of refractive index of the liquid crystal material according to the present invention. The liquid crystal material has only one main optical axis. The plane perpendicular to the main optical axis is a circular plane, which shows that the refractive indexes of the materials are equal in the direction perpendicular to the main optical axisn x =n y ). The electromagnetic wave does not change when it is transmitted along the main optical axis. If the propagation direction of electromagnetic wavekAt an angle to the main optical axis of the liquid crystal molecules, the vibration direction of the electric field is not within a circle of equal refractive index, e.g. along the line of FIG. 15n e Direction. Then, with respect to the movement in the main optical axis direction,n e the refractive index in the direction increases and the moving speed of the electromagnetic wave in the direction decreases. Therefore, when the liquid crystal is deflected to different degrees under the drive of the applied voltage, the propagation direction of the electromagnetic wave forms an included angle with the main optical axis of the liquid crystal to different degrees. So that the vibration electric field corresponds to different refractive indexes or dielectric constants. The motion speeds of the electromagnetic waves in liquid crystal molecules in different deflection states are different, and further the required amplitude modulation is achieved in a certain direction.
The invention provides a wave velocity and synthesis and control method of a liquid crystal array antenna based on the method, and a specific flow thereof is shown in fig. 16. First, a radiation pattern function in a certain direction needs to be given for a desired array antenna. Secondly, the feed weight vector of each array element is determined by approximating a given pattern function. After determining the feed weight vector for each radiating element, each is assigned by the phase decomposition method described above>Performing phase decomposition on the array plane to determine the distribution of phase decomposition array elements corresponding to the direction of a certain beam, thereby determining each +.>Corresponding phase distribution. Finally, by loading voltage driving signals to each phase decomposition array element, the array distribution of the liquid crystal deflection states in the phase decomposition array elements is realized, thereby determining each ∈>The corresponding amplitude is the value over the two decomposition units. Finally, the desired radiation pattern of the array antenna is achieved by superposition of the radiation field on the phase-resolved array elements in the far field region. When the beam direction of the array antenna changes, the antenna control system refreshes the control voltage on the corresponding radiation unit in the array antenna, so that the switching of the beam direction is realized, and the reproduction of the array antenna pattern is realized. Fig. 17 shows an embodiment of an equilobe array antenna pattern with 60 ° pointing implemented by phase decomposition.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (5)
1. A liquid crystal array antenna beam forming and self-adaptive control method based on phase decomposition is characterized by comprising the following steps,
s1, giving a radiation pattern function of a desired array antenna;
s2, determining the feeding weight vector of each array element by approximating a given pattern function；
S3, for eachPerforming phase decomposition on an array plane, and determining the phase decomposition array element distribution corresponding to the direction of a certain wave beam;
s4, realizing array distribution of liquid crystal deflection states in the phase decomposition array elements through a driving system of the antenna so as to realize a desired array antenna radiation pattern.
2. The method for beamforming and adaptive control of a liquid crystal array antenna based on phase decomposition according to claim 1, wherein the method comprises the steps of: in step S3The magnitude of the components of the array element radiation fields Eij in the x-axis and the y-axis in the two corresponding phase decomposition units is realized by adjusting the deflection degree of the liquid crystal in the phase decomposition array elements.
3. The method for forming and adaptively controlling the beam of the liquid crystal array antenna based on the phase decomposition according to claim 2, wherein the method comprises the following steps: the degree of deflection adjustment of the liquid crystal includes applying an electric field and controlling the magnitude change thereof, and polarizing liquid crystal molecules in the liquid crystal material to generate different degrees of deflection.
4. The method for beamforming and adaptive control of a liquid crystal array antenna based on phase decomposition according to claim 1, wherein the method comprises the steps of: step S4 includes determining each of the phase-resolved array elements by applying a voltage drive signal to each of the phase-resolved array elements to achieve an array distribution of liquid crystal deflection states in the phase-resolved array elementsThe corresponding magnitude is the value of the two decomposition units; the desired radiation pattern of the array antenna is achieved by superposition of the radiation field on the phase-resolved array elements in the far field region.
5. The method for beamforming and adaptive control of a liquid crystal array antenna based on phase decomposition according to claim 1, wherein the method comprises the steps of: in step S4, when the beam direction of the array antenna changes, the control voltage on the corresponding radiation unit in the array antenna is refreshed by the control system of the antenna, so as to realize the switching of the beam direction and achieve the reproduction of the array antenna pattern.
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