CN116776701B - Strong coupling broadband antenna array edge effect optimization method for improving instantaneous bandwidth - Google Patents
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Abstract
The invention discloses a strong coupling broadband antenna array edge effect optimization method for improving instantaneous bandwidth. Firstly, obtaining a scattering parameter and an active unit gain pattern of a full aperture port of a limited strong coupling broadband antenna array through simulation or actual measurement, and taking the scattering parameter and the active unit gain pattern as input data of an optimization method; then according to the mathematical relation between the active reflection coefficient of the unit and the array gain and the feed amplitude and phase excitation, for a given beam scanning angle, establishing a non-convex optimization problem which takes the maximized array gain as an objective function, takes the active reflection coefficient of the full aperture unit as a constraint condition and takes the same feed amplitude and phase as design variables in the expected signal instantaneous bandwidth; and finally, by introducing proper mathematical transformation and adopting an iterative solving thought, the feed amplitude and phase excitation in the instantaneous bandwidth are efficiently solved by using a convex optimization algorithm. The optimization method improves the instantaneous bandwidth characteristic of the antenna array while inhibiting the edge truncation effect.
Description
Technical Field
The invention belongs to the field of ultra-wideband phased array antennas, and relates to how to improve the instantaneous bandwidth of a full-aperture ultra-wideband strong-coupling antenna array when the edge effect of the antenna array is restrained. The method specifically refers to a finite large ultra-wideband strong coupling antenna array which is carefully designed by utilizing a periodic boundary, and meets the requirement of active standing waves in the instantaneous bandwidth of a full aperture unit by regulating and controlling the same group of feed amplitude and phase in a given instantaneous bandwidth, and meanwhile, the maximization of the array gain in the instantaneous bandwidth of the full aperture unit is realized.
Background
With the rapid development of radio electronics technology, carrier platform radio subsystems have placed increasingly stringent demands on phased array antennas that they carry. The ultra wideband is shown in electrical performance to support the system multifunctional integrated function application, and the miniaturization is shown in structure to support the flat design trend of the carrier platform. This presents a significant challenge to conventional phased array antenna designs. For example, if a Vivaldi phased array antenna is used, while it can meet the requirement of ultra wideband, its ultra wideband operating mechanism determines that its longitudinal dimension is difficult to further effectively reduce; if a phased array antenna in the form of a planar microstrip antenna is used, although the miniaturization requirement of the system can be met, the narrow-band radiation structure of the phased array antenna determines that the working bandwidth of the phased array antenna is difficult to further expand. In order to realize ultra-wideband and miniaturization simultaneously, the strong coupling antenna array is the solution with the highest potential at present, and belongs to research hot spots and research focuses of international ultra-wideband low-profile phased array antennas.
The ultra-wideband radiation characteristic of the strong coupling antenna array is structurally and radically caused by purposely reducing the unit spacing and the unit size; the fundamental reason is that the reduced cell spacing introduces extra capacitive coupling in radiation mechanism, effectively counteracts inductance brought by the reflecting floor at low frequency, and enables the array aperture to form nearly continuous current distribution, thereby expanding the low-frequency bandwidth of the antenna array and realizing ultra-wideband miniaturized design of the antenna. Generally, similar to other phased array antenna unit simulation design methods, the strong coupling antenna array is designed based on an infinite period unit under constant amplitude and constant difference phase feed excitation, and then the finite large array design is performed by using the unit. Obviously, the finite large array antenna units are structurally truncated relative to the infinite periodic units. Specifically, since a certain number of antenna units still exist around the middle part unit of the limited large array, the environment of the middle part unit is similar to that of the infinite period unit (especially when the array scale is larger), the edge generated waves generated by edge truncation are difficult to reflect to the middle part unit, the influence of the truncation effect is relatively small, and the active standing waves in certain frequency bands are deteriorated to a certain extent; for edge portion cells, where the surrounding environment is significantly different from that of infinite period cells, the intense Bian Sheng waves will severely affect their radiation performance, manifested as severe degradation of the edge portion cell active standing wave and reduced gain. Therefore, the edge effect can cause the ultra-wideband matching characteristic of the full aperture full unit of the antenna array to be deteriorated to different degrees, the energy input by the edge unit is not effectively fed into the antenna array, but directly reflected at the port, and the reflected power can have a larger influence on the back-end device.
In order to effectively inhibit the influence of the edge truncation effect on the radiation performance of the limited large-strong-coupling antenna array, researchers start from the structural design of the strong-coupling antenna array and put forward various methods for improving the array edge truncation effect. In the document A novel broadband ANTENNA ARRAY WITH TIGHTLY coupled octagonal RING ELEMENT, an author designs a 24 multiplied by 3 octagonal ring strong coupling antenna array, in order to ensure the periodic environment of the octagonal ring units as far as possible, only the central 16 units are used as effective feed units, and the rest units are all dummy units, so as to fully absorb edge generated waves generated by edge truncation, and finally inhibit the influence of the edge truncation effect on the active standing waves of the antenna array to a certain extent. However, the physical aperture size of the antenna can be obviously increased by using an extra large number of dummy elements in the method, and the aperture efficiency of the antenna array is reduced. In the document Edge-born waves in connected arrays:A fine X INFINITE ANALYTICAL presentation, the authors found by quantitative analysis of the Edge-wave of a finite large X infinite antenna array: the edge port characteristic impedance is designed to a larger value to effectively absorb the partially reflected Bian Shengbo, thereby improving the edge chopping effect. But this method has the disadvantage of loading the dummy, but also does not match the characteristic impedance of 50 ohms in engineering application, and is difficult to use directly. In the invention patent with the patent number of CN105846081, the inventor designs a dual polarization Jiang Ouge ultra-wideband phased linear array under the one-dimensional period boundary condition, in order to restrain the strong edge cutting effect in the non-array direction of the linear array, a two-unit array design is adopted for a vertical polarization unit along the non-array direction, and the two units form an antenna unit through a Wilkinson power divider. Meanwhile, in order to lengthen the current path, the influence of Bian Sheng waves is reduced, and the vertically polarized border cell extends vertically toward the floor and is electrically connected with the floor. For horizontally polarized cells, since the array has been designed with a limited array size along it, the effect of edge cut-off on it is significantly smaller than for vertically polarized cells, which the inventors have only performed an extension treatment. Although the method can inhibit the edge wave generated by the edge cut-off effect to a certain extent and improve the impedance matching performance of part of units at part of frequency points, the method is difficult to realize the good impedance matching of the ultra-wideband full-aperture units, and the active standing wave performance of part of units at part of frequency points is still poor. In the invention patent with the patent number of CN112216980, the inventor designs a full aperture strong coupling ultra-wideband single polarization dipole phased array antenna, in order to restrain the influence of edge cut-off effect, an antenna array excites two mirror symmetry dipole units through a Wilkinson power dividing circuit in a non-array direction, two edge ports of the array in the array direction adopt a method of extending dipole arms, vertical metal walls are added at the edges of the array to replace a dummy of a traditional matching resistor, the effective restraint of the edge cut-off effect is realized on the premise of not using the dummy, the array low frequency band standing wave is improved, finally, the active standing wave of the full port unit is smaller than 3 in the working frequency band range of 1 GHz-4 GHz, and good matching and edge effect restraining effects are realized. However, the bandwidth suitable for the method is relatively narrow, and the port active standing wave still deteriorates to different degrees in the case of antenna array scanning.
In practice, the active standing wave characteristics of the ports characterize the port matching characteristics of all the elements of the antenna array when they are simultaneously operating. According to the theory of a multi-port microwave network, the active standing wave is determined by the port passive scattering parameter and the port excitation. Therefore, the edge cut-off effect suppression method based on the strong coupling antenna array structure design is performed from the angle of the design freedom of regulating the port passive scattering parameter. However, it is increasingly difficult to meet the ultra-wideband and ultra-wideband application requirements of the full aperture antenna array by adjusting the passive scattering parameters of the ports to improve the freedom of the active standing waves. For this reason, the degree of freedom of adjustment and control of the amplitude and phase excitation of the antenna array ports is gradually favored by researchers. In literature CHARACTERISTIC EXCITATION TAPER FOR ULTRAWIDEBAND TIGHTLY COUPLED ANTENNA ARRAYS, characteristic mode decomposition is performed on an active impedance matrix obtained through simulation or actual measurement, so that characteristic current amplitude distribution corresponding to a characteristic mode with high mode significance at a specific frequency point is found out, and all units of the limited large array have excellent impedance matching performance under the condition of using the characteristic current amplitude distribution. However, the method is essentially a narrow-band method, the full-unit impedance matching characteristic is difficult to improve in the ultra-wide band range, the influence on the gain pattern is not considered in the solving of the characteristic current amplitude distribution, and the degree of freedom of the regulation of the excitation phase is not considered. The invention patent with the patent number of CN112216980 proposes an edge cut-off effect based on feed amplitude and feed phase regulation, and by quantitatively analyzing the influence of the edge cut-off effect on an array active standing wave and a gain pattern, an optimization problem with the array gain on a given frequency point and a scanning angle as an objective function and the maximum active standing wave under a full-unit full-scanning angle as a constraint condition is established in an ultra-wideband working frequency band, and an iterative solution idea is used, so that an efficient solution method of an iterative convex optimization algorithm is provided, the full-aperture unit active standing wave is realized to be smaller than 3 within a bandwidth of 10 octaves and a scanning range of plus or minus 45 degrees, and the edge cut-off effect is obviously restrained. However, the method requires the use of different sets of feed amplitude and phase excitation for different operating frequency points, and if the same set of feed amplitude and phase excitation is used in a certain instantaneous bandwidth, the suppression effect of the edge truncation effect will be deteriorated. That is, the suppression method in this patent does not take into account the instantaneous bandwidth characteristics of the actual signal. Considering that the instantaneous bandwidth characteristic of an actual signal often exists, the influence on the instantaneous bandwidth of the signal and how to improve the instantaneous bandwidth characteristic of an antenna array need to be considered while the edge truncation effect is restrained by using the degree of freedom of feed amplitude and phase regulation.
Disclosure of Invention
In view of the above technical background, the present invention proposes a method for suppressing the edge effect of a strongly coupled wideband antenna array for improving the instantaneous bandwidth. The method fully considers the quantitative relation between the active reflection coefficient and the array gain of the ultra-wideband full-aperture strong-coupling array unit and the feed amplitude and phase excitation, and suppresses the edge truncation effect of the antenna array through the optimal design of the same group of feed amplitude and phase within a given instantaneous bandwidth. Finally, for an ultra-wideband dual-polarized antenna array with the working frequency band of 0.2 GHz-2 GHz Jiang Ouge, the active standing wave of the full aperture unit is less than or equal to 3 in the instantaneous bandwidth of 200MHz and the scanning range of positive and negative 45-degree beams, and the instantaneous bandwidth of the antenna array is improved while the edge cut-off effect is obviously restrained.
The detailed technical scheme of the invention is as follows: the method comprises the steps of optimally designing a strong coupling ultra-wideband antenna array unit in an expected working frequency range under an infinite period environment (the expected working frequency range of the strong coupling ultra-wideband antenna array is 0.2 GHz-2 GHz in the embodiment of the invention), and then performing limited large array group design according to the antenna unit and the unit spacing. In the finite large array group design, a method for partially suppressing the edge truncation effect (such as loading a dummy, using an RLC loading structure by an edge unit, and the like) can be adopted according to specific space structure limitations. And then, based on full-wave simulation software simulation or antenna array sample actual measurement, obtaining a full-aperture antenna unit scattering parameter matrix and an active unit gain direction diagram, and based on antenna array theory, inducing mathematical relations of unit active reflection coefficients and array gain and feed amplitude and phase excitation. And finally, for a given beam scanning angle, establishing an optimization problem which takes the maximized array gain as an objective function, takes the active reflection coefficient of the full aperture antenna unit as a constraint condition and takes the same set of feed amplitude and phase as design variables in the expected signal instantaneous bandwidth, and designing an efficient optimization algorithm to solve the optimal feed amplitude-phase excitation in the signal instantaneous bandwidth.
The number of array elements of a certain polarization (horizontal polarization or vertical polarization) of the ultra-wideband strong-coupling planar antenna array with perfect structural design is equal to N=P×Q, and the working frequency band is f epsilon [ f L,fH ], wherein f L and f H respectively represent the lowest and highest working frequencies in the working frequency band. The instantaneous bandwidth of the antenna array transmitting or receiving signals is BW, any working frequency point of a point in the instantaneous bandwidth is F epsilon [ F l,fh ], wherein F l and F h respectively represent the lowest and highest working frequencies in the instantaneous bandwidth, the working frequencies in the instantaneous bandwidth are uniformly dispersed according to an interval delta F, namely F i＝fl + (i-1) delta F, and the total number of the discrete frequency points is F. The antenna array scattering matrix at the frequency point f i in the instantaneous bandwidth obtained by simulation or test is S (f i), the active unit gain direction diagram of the nth antenna unit at the frequency point f i is based on the microwave network theory and the electromagnetic vector superposition principle, and when the antenna array scans to the angle/> , the active reflection coefficient of the nth antenna port, the active standing wave of the nth antenna port and the array gain direction diagram can be calculated according to the following formulas:
Wherein S n,m(fi) represents the (m, n) th element of the scattering matrix S (f i), that is, the coupling coefficient of the mth element and the nth element of the strong-coupling antenna array at the operating frequency point f i in the instantaneous bandwidth. Respectively represent the included angle with the z axis and the included angle with the x axis under the spherical coordinate system. I m and/> represent the feed amplitude and phase excitation, respectively, of the mth antenna port of the antenna array within the instantaneous bandwidth. To facilitate the following description of the optimization problem, the equations (1) and (3) may be written in a matrix form as follows:
Wherein denotes the vector of feed phase excitations of the antenna array within the instantaneous bandwidth. I= [ I 1,I2,…,IN]T ] represents a vector constituted by the feed amplitude excitation of the antenna array within the instantaneous bandwidth. w represents the complex excitation vector consisting of the feed amplitude and phase excitation vector within the instantaneous bandwidth. The/> represents an array flow pattern matrix consisting of the active cell gain pattern at the operating frequency point f i within the instantaneous bandwidth. S n(fi) represents a column vector consisting of the nth row element of the antenna array port scattering matrix S (f i) within the instantaneous bandwidth. The/> represents the Hadamard product and the (-) H represents the conjugate transpose.
The problem of suppressing array edge cut-off effects using the same set of fed amplitude-phase excitations for an antenna array within a desired instantaneous bandwidth can be described as: for any operating frequency point f i within the desired instantaneous bandwidth, under the condition that the active reflection coefficient of the full aperture array unit is less than or equal to the given maximum reflection coefficient ρ, the array gain of the beam scanning direction is maximized by the same group of feed amplitude-phase excitation, and such a problem can be summarized as the following optimization problem:
Where C represents a complex set and U represents a column vector with all elements 1. Since the objective function is to maximize an absolute value function, the objective function is non-convex. Meanwhile, in the first constraint, the optimization variable I n is used as an upper bound constraint, and this type of constraint belongs to a non-convex constraint, so that the optimization problems (6) - (7) are typical non-convex optimization problems, and mathematical studies show that it is difficult to find a globally optimal solution of the problem in a limited time.
By introducing a quadratic equivalent mathematical transformation, the optimization problems (6) - (7) can be equivalently converted into the following optimization problems:
Wherein,
By introducing the auxiliary variable t, and then by some simple mathematical derivation, the optimization problems (8) - (9) can be equivalently translated into the following optimization problems:
It is easy to find that the first two constraints in (12) are both in the form of differences between two convex functions, so that the two constraints can be approximated using convex upper bound functions in the corresponding first-order form of expansion. Specifically, by performing one-step form expansion on the complex variable w, the following two constant inequality can be obtained:
Wherein represents any one of the possible solutions to the optimization problems (11) - (12), and/> can be calculated according to the conventional constant amplitude stepping phase of the phased array antenna, and as an initial solution,/> can be calculated according to the following formula:
Substituting equations (13) and (14) into equation (12), and using the iterative concept, the optimization problems (11) - (12) can be converted into a solution of a series of convex optimization problems, wherein the optimization problem of the first solution can be expressed as:
Wherein Re (·) represents the real operator, (wl-1,tl-1) and represents the solution of the optimization problem corresponding to the first-1 iteration. According to equation (15), t l-1 can be calculated as follows:
The meaning represented is the value of the objective function in the optimization problem of the first-1 iteration solution. Obviously, in such an iterative manner, the optimization problems (16) - (17) are a convex optimization problem, which can be solved efficiently using a convex optimization tool box integrated with software such as MATLAB. Once obtained (w l,tl), the iteration number i is increased (i.e. let l=l+1) and updated as follows:
The convex optimization problem (16) - (17) is then solved again until the maximum number of iterations is reached or a given convergence criterion is met, and the iteration is terminated (the absolute value of the difference between the objective functions obtained in the two iterations is smaller than the given precision).
The method for optimizing the edge effect of the strong-coupling broadband antenna array for improving the instantaneous bandwidth has the main advantages that:
1. The limited strong coupling ultra-wideband antenna array structural design and amplitude and phase regulation post-treatment are combined to inhibit the edge truncation effect, and the influence of an amplitude and phase regulation method on the instantaneous bandwidth of a signal is quantitatively analyzed for the first time;
2. the influence of amplitude-phase regulation on the active reflection coefficient of an antenna array and the array gain is considered in the signal instantaneous bandwidth, a non-convex optimization model for inhibiting the edge cut-off effect based on the same group of feed amplitude and phase excitation in the signal instantaneous bandwidth is established, and a method for approximating the upper bound of the non-convex optimization model can be used for subtracting according to two convex functions, so that the meta-non-convex optimization problem is converted into a convex optimization problem, and further, the efficient solution is carried out;
3. By using the method provided by the invention, the full aperture unit active standing wave is smaller than 3 by using the same group of feed amplitude and phase excitation within the 200MHz instantaneous bandwidth and the positive and negative 45-degree beam scanning range, the array gain is not affected basically (part of frequency points are slightly improved compared with the traditional constant amplitude stepping phase excitation gain), and the application requirement of the broadband radar is met.
Drawings
Fig. 1 is a top view of a limited strong coupling ultra wideband dual polarized planar antenna array.
Fig. 2 is a port number of a horizontal polarization unit of the ultra-wideband dual-polarized planar antenna array with limited strong coupling.
Fig. 3 is a port number of a vertical polarized unit of the ultra-wideband dual-polarized planar antenna array with limited strong coupling.
Fig. 4 is a graph of active standing waves of a horizontally polarized full aperture unit when the antenna array is side-polarized within an instantaneous bandwidth.
Fig. 5 is a graph of standing waves when the E-plane of the antenna array horizontally polarized full aperture unit is scanned to 45 degrees within the instantaneous bandwidth.
Fig. 6 is a graph of standing waves when the H-plane of the antenna array horizontally polarized full aperture unit is scanned to 45 degrees within the instantaneous bandwidth.
Fig. 7 is a graph of an active standing wave when the antenna array horizontally polarizes a full aperture unit in a transient bandwidth and is laterally irradiated by the method provided by the invention.
Fig. 8 is a graph of standing waves when the E-plane of the horizontal polarized full aperture unit of the antenna array is scanned to 45 degrees in the instantaneous bandwidth obtained by optimizing the method provided by the invention.
Fig. 9 is a graph of standing waves when the H-plane of the horizontal polarized full aperture unit of the antenna array is scanned to 45 degrees in the instantaneous bandwidth obtained by optimizing the method provided by the invention.
Fig. 10 is a gain pattern of the antenna array when the horizontal polarization component side-firing is performed in the instantaneous bandwidth obtained by optimizing the method provided by the invention.
Fig. 11 is a gain pattern when the plane of the horizontal polarization component E of the antenna array is scanned to 45 degrees in the instantaneous bandwidth obtained by optimizing the method provided by the invention.
Fig. 12 is a gain pattern when the horizontal polarization component H of the antenna array is scanned to 45 degrees in the instantaneous bandwidth optimized by the method provided by the invention.
Fig. 13 is a graph showing the maximum gain with frequency when the horizontal polarization component of the antenna array is side-projected, which is obtained by the method of the present invention and the conventional constant amplitude step phase excitation method in the instantaneous bandwidth.
Fig. 14 is a graph showing the maximum gain with frequency when the E-plane of the horizontal polarization component of the antenna array obtained by the method of the present invention and the conventional constant amplitude step phase excitation method scans 45 degrees in the instantaneous bandwidth.
Fig. 15 is a graph showing the maximum gain variation with frequency when the horizontal polarization component H-plane of the antenna array is scanned by 45 degrees, which is obtained by the method provided by the invention and the conventional constant amplitude step phase excitation method in the instantaneous bandwidth.
Detailed Description
As shown in fig. 1, the effectiveness of the proposed method of the present invention was verified using an ultra wideband dual polarized strongly coupled planar phased array antenna of the invention patent number CN114744409 a. The working frequency band of the antenna array is 0.2 GHz-2 GHz, the number of two polarized array elements is P multiplied by Q=6 multiplied by 8=48, and the antenna array sequentially comprises a wide-angle impedance matching layer, an antenna unit layer, a double-Y feed balun, a resistive frequency selective surface, an impedance transformation network layer and a reflecting floor from the upper layer to the lower layer. The antenna unit layer comprises a horizontal polarization unit dipole unit and a vertical polarization unit dipole unit which are mutually and orthogonally arranged and printed on the same dielectric substrate with the feed balun. The antenna arrays are arranged in a rectangular grid. The cell pitch was 66mm in both the x and y directions. In order to fully utilize the limited arraying space, a dummy loading method is not used when the edge truncation effect is restrained, and an array edge resonant circuit formed by lumped resistance, lumped capacitance and lumped inductance is loaded on the edge of the array. The antenna array has horizontal polarization component port numbers as shown in fig. 2 and vertical polarization component port numbers as shown in fig. 3.
The curves of the standing waves when the antenna array is subjected to full-wave simulation, obtained through full-port side emission, E-plane scanning at 45 degrees and H-plane scanning at 45 degrees, of the horizontal polarization unit are respectively shown in fig. 4, 5 and 6. It can be seen that the active standing waves at the ports near the edges of the array are significantly degraded, especially near low frequencies, and that the degradation of the standing waves during scanning is more severe than during side-firing. And then, full-wave simulation is carried out to obtain a full-port scattering parameter of a specific frequency point and an active unit gain pattern which are used as input data of the method and are used for improving instantaneous bandwidth when array edge deblocking effects are restrained.
As can be seen from fig. 4, 5 and 6, the active standing wave deterioration in the low frequency band is remarkable, so the method of the present invention mainly suppresses the low frequency band edge cut-off effect. It is assumed that the instantaneous bandwidth of the signal is bw=200 MHz, and the corresponding operating frequency band is 0.2GHz to 0.4GHz. After the method for improving the instantaneous bandwidth and inhibiting the edge cut-off effect is used, the obtained curves of the active standing waves along with the working frequency change when the side-emission and E-plane scanning of the horizontal polarization full-aperture unit are 45 degrees are respectively shown in figures 7, 8 and 9, the active standing waves of the full-aperture array unit are easily found to be smaller than 3 in the whole instantaneous bandwidth and 5-degree beam scanning range, and the impedance matching performance of the full-aperture array unit in the whole instantaneous bandwidth and the scanning range is good by using the method provided by the invention, so that the array edge effect is obviously inhibited. Further, gain patterns are shown in fig. 10, 11 and 12 after optimization at 0.2GHz, 0.25GHz, 0.3GHz, 0.35GHz and 0.4GHz, and the gain patterns cover the expected scanning direction when the E face scans 45 degrees and the H face scans 45 degrees, and the direction patterns are good. The graphs of the maximum gain along with the frequency change when the antenna array horizontal polarization component side-emission, the E-plane scanning 45 degrees and the H-plane scanning 45 degrees are obtained by using the amplitude-phase regulation method and the traditional constant amplitude stepping phase excitation method are respectively shown in figures 13, 14 and 15. It is easy to find that in the instantaneous working bandwidth, the gain of most frequency division points in the instantaneous bandwidth is slightly improved for the side-shooting, the gain of a low-frequency end is slightly improved when the E-plane scans 45 degrees, the gain of a high-frequency band is slightly reduced, and the overall gain is slightly improved when the E-plane scans 45 degrees. In general, the method has small influence on the array gain, and partial frequency point gain is slightly improved, so that the effectiveness of the method provided by the invention is demonstrated. The edge cut-off effect optimization result of the vertical polarization component of the strong coupling ultra-wideband dual-polarized antenna array in the instantaneous bandwidth is not given here for the sake of space.
The foregoing description of the invention and its embodiments, as provided to those skilled in the art of the invention, is to be considered as illustrative and not restrictive. The engineering technician can implement the specific operation according to the idea of the invention claims in combination with the specific problem, and naturally can also make a series of reasonable changes to the embodiment according to the above. All of the foregoing should be considered as being within the purview of the present invention.
Claims (1)
1. The method is mainly characterized in that firstly, strong coupling ultra-wideband antenna array units are designed under an infinite period environment and form a finite large array, then, based on full-wave simulation or actual measurement, scattering parameters of specific frequency points f i in the instantaneous bandwidth of a full-aperture antenna unit and an active unit gain pattern are obtained, and mathematical relations between active reflection coefficients and array gains of specific frequency point units in the instantaneous bandwidth and feed amplitude and phase excitation are generalized:
Wherein S n,m(fi) represents a coupling coefficient of an mth unit and an nth unit of the antenna array at an operating frequency point f i in an instantaneous bandwidth, represents an included angle with a z axis and an included angle with an x axis in a spherical coordinate system, I m and/> represent feed amplitude and phase excitation of an mth antenna port of the antenna array in the instantaneous bandwidth, respectively,/> represents a desired beam scanning angle, and f l and f h represent minimum and maximum operating frequencies in the instantaneous bandwidth, respectively, by adopting matrix operation, equations (1) and (2) can be respectively equivalently expressed as:
Wherein denotes a vector constituted by feeding phase excitation in instantaneous bandwidth, i= [ I 1,I2,…,IN]T denotes a vector constituted by feeding amplitude excitation of an antenna array in instantaneous bandwidth, w denotes a complex excitation vector constituted by feeding amplitude and phase excitation vector in instantaneous bandwidth,/> denotes an array flow pattern matrix constituted by active element gain pattern at operating frequency point f i in instantaneous bandwidth, S n(fi) denotes a column vector constituted by nth row element of antenna array port scattering matrix S (f i) in instantaneous bandwidth,/> denotes hadamard product, (·) H denotes conjugate transpose, and for any operating frequency point f i in instantaneous bandwidth, the optimization problem of maximizing array gain with same feeding amplitude phase excitation can be generalized to the following non-convex optimization problem:
wherein C represents a complex set, U represents a column vector of all elements 1, and the non-convex optimization problem in (5) - (6) can be converted into an iterative convex optimization problem by introducing an appropriate mathematical transformation and adopting an iterative solution idea, wherein the first iterative convex optimization problem is:
Wherein Re (·) represents the real operator, represents the feasible solution of the optimization problem (7) - (8), (w l-1,tl-1) and represents the solution of the optimization problem corresponding to the first-1 iteration, t l-1 can be calculated according to the following formula:
in such an iterative manner, the optimization problem (7) - (8) is a convex optimization problem, which can be solved efficiently using a convex optimization tool box integrated with software such as MATLAB, and once obtained (w l,tl), the number of iterations i is increased (i.e., let i=l+1) and updated according to the following equation:
the convex optimization problem (7) - (8) is then solved again until the maximum number of iterations is reached or a given convergence criterion is met, and the iteration is terminated.
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| WO2011008146A1 (en) * | 2009-07-16 | 2011-01-20 | Saab Ab | Method and wideband antenna system to minimise the influence of interference sources |
| CN110336627A (en) * | 2019-07-10 | 2019-10-15 | 电子科技大学 | Array antenna amplitude-phase regulator control system and its implementation based on time-modulation |
| CN114499581A (en) * | 2022-01-25 | 2022-05-13 | 电子科技大学 | Aperture-level same-frequency full-duplex phased-array antenna broadband coupling signal cancellation method |
| CN114709616A (en) * | 2022-04-13 | 2022-07-05 | 电子科技大学 | Ultra-wideband strong coupling antenna array edge effect suppression method based on amplitude and phase regulation |
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| CN110336627A (en) * | 2019-07-10 | 2019-10-15 | 电子科技大学 | Array antenna amplitude-phase regulator control system and its implementation based on time-modulation |
| CN114499581A (en) * | 2022-01-25 | 2022-05-13 | 电子科技大学 | Aperture-level same-frequency full-duplex phased-array antenna broadband coupling signal cancellation method |
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