Non-dispersion forming method for near-field track of electromagnetic wave

Abstract

The invention discloses a dispersion-free forming method for an electromagnetic wave near-field track, and belongs to the technical field of electromagnetic fields and electromagnetic waves. The method comprises a near-field main beam track non-dispersion forming method and a non-diffraction beam non-dispersion focusing method. According to the near-field main beam trajectory non-dispersion forming technology, a delay coefficient of an array antenna reference unit is calculated by utilizing a space wave path difference of an intersection point of a trajectory function tangent line and a trajectory function evolvent of the array antenna reference unit and an over-reference unit; according to the non-diffracting wave beam non-dispersion focusing method, a Bessel wave beam focusing mechanism is utilized, and a time delay coefficient of a common unit of an array is calculated through a position relation between a conventional unit and a reference unit on the array and a wave beam directional angle. According to the dispersion-free forming method based on the electromagnetic wave near-field trajectory, a near-field main wave beam trajectory with a 300GHz frequency band and a trajectory being a parabola and a semicircle is realized.

Description

Technical Field

[0001] The present invention belongs to the field of electromagnetic field and electromagnetic wave technology, and specifically relates to a dispersion-free shaping method for electromagnetic wave near-field trajectories based on time delay control. Background Art

[0002] Precisely controlling the propagation trajectory of electromagnetic waves in space is one of the core technologies for improving the performance of systems such as communications and radar. In recent years, electromagnetic control technology based on structured beams has become a research hotspot because it can achieve main beamforming according to a predetermined trajectory function in the near-field region. Existing technologies mostly construct near-field trajectories based on the phase-wavefront mapping relationship. However, due to the strong correlation between the phase parameter and frequency, the shaped beam produces significant frequency dispersion effects in broadband signals. With the rapid growth of signal bandwidth requirements in communication systems, beam distortion caused by dispersion effects has become a key bottleneck restricting communication speeds. Therefore, a new beamforming technology that can eliminate frequency dispersion is urgently needed. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention provides a method for dispersion-free shaping of electromagnetic wave near-field trajectories. Based on a time-delay compensation mechanism, the method overcomes the spatial dispersion defects of broadband signals caused by existing phase control technologies and achieves broadband stability of the main beam trajectory.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for dispersion-free shaping of electromagnetic wave near-field trajectories includes a method for dispersion-free forming a near-field main beam trajectory and a method for dispersion-free focusing a non-diffraction beam. The method is used to construct a basic time delay compensation coefficient of an array unit. The non-diffraction beam dispersion-free focusing method is then used to establish an additional time delay compensation coefficient of the array unit. Based on the basic time delay compensation coefficient and the additional time delay compensation coefficient, all array units are delayed accordingly to perform dispersion-free shaping on the main beam, thereby obtaining a main beam with broadband stability.

[0006] The dispersion-free near-field main beam trajectory formation method is based on the geometric mapping relationship between the involute and the wavefront of the near-field trajectory function of the electromagnetic wave, and constructs the basic delay compensation coefficient of the array unit through an analytical model of the spatial wave path difference between the array reference unit and the trajectory involute.

[0007] The non-diffraction beam dispersion-free focusing method combines the propagation characteristics of Bessel beams and establishes additional delay compensation coefficients of array units based on the spatial position vectors of array regular units and array reference units and beam pointing angle parameters.

[0008] Furthermore, the method for forming a near-field main beam trajectory without dispersion includes:

[0009] A1. Calculate the involute function C* based on the predetermined shaping trajectory function C.

[0010] Specifically, the trajectory function C is expressed as:

[0011]

[0012] Among them, x(t), y(t), and z(t) are the parameter expressions of the trajectory function C in the x, y, and z directions with t as the variable, respectively.

[0013] The involute function C* is expressed as:

[0014]

[0015] Where λ is an arbitrary constant, is the unit tangent vector of the trajectory function C, and s is the arc length parameter of the trajectory function C, which is expressed as:

[0016]

[0017] in, To find the first-order derivative of each component in the trajectory function C function expression, t0, a, and b are constants.

[0018] A2. Select m units in the array as reference units and record them as a i , i=1,2,...,m.

[0019] The m reference units are selected along the longitudinal or transverse axis of the array, and it is necessary to ensure that the longitudinal or transverse coordinates of the selected reference units cover the coordinates of all units on the array surface, and the coordinate values ​​are not repeated.

[0020] Over the reference unit a i Draw a tangent line to the trajectory function C, which intersects the involute line C* at p i ,i=1,2,...,m;calculate a i With p i The spatial path difference is denoted as l i , then the array reference unit a i The basic delay coefficient is expressed as:

[0021] τ i =l i / c

[0022] Where c is the propagation speed of electromagnetic waves in free space.

[0023] Furthermore, the non-diffraction beam dispersion-free focusing method includes:

[0024] Select the reference cell a in the array i n with the same horizontal axisi Regular units, denoted as b ji , ji=1,2,...,n i , calculate b ji with a i The spatial path difference is denoted as ρ ji .

[0025] Therefore, the base unit a i The corresponding n i The additional delay compensation coefficient of a conventional unit is expressed as:

[0026] ν′ ji =ρ ji ×sin(θ0) / c

[0027] Where θ0 is any angle in the interval (0°, 90°);

[0028] Combined with the basic delay coefficient, this n i The delay compensation coefficient of a conventional unit is expressed as:

[0029] v ji =ρ ji ×sin(θ0) / c+τ i

[0030] Using the reference unit a i The delay compensation coefficients of the corresponding conventional units are calculated to obtain the delay compensation coefficients of all units in the array antenna.

[0031] Furthermore, the electromagnetic wave near-field trajectory dispersion-free shaping method is applicable to a two-dimensional planar array or a three-dimensional curved array; the topological structure of the array includes a rectangular grid, a circular grid or any irregular arrangement.

[0032] Furthermore, the antenna form of the array unit is a dipole form, a microstrip patch form, or a composite structure radiator form.

[0033] The core innovation of the present invention is:

[0034] The present invention replaces traditional phase parameter control with time delay parameters, uses a path difference compensation mechanism to eliminate frequency correlation, and combines the coordinated control of self-acceleration trajectory generation and non-diffracting beam focusing to ensure that the main beam radiated by the array antenna in the near-field area strictly follows the preset trajectory function distribution and maintains dispersion-free characteristics within a wide frequency band.

[0035] Compared with the existing technology, the present invention breaks through the phase-frequency coupling limitation through the delay control mechanism, realizes the broadband stability of the main beam trajectory, and can significantly improve the system performance in the fields of millimeter wave communication, ultra-wideband radar imaging, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of the near-field main beam trajectory dispersion-free formation technology;

[0037] Figure 2 Schematic diagram of non-diffraction beam dispersion-free focusing technology;

[0038] Figure 3 A graph showing the standing wave ratio and gain of the dipole unit used in Examples 1, 2, and 3 as a function of frequency;

[0039] Figure 4 is the near-field electric field distribution diagram of Example 1;

[0040] Figure 5 This is the near-field main beam trajectory fitting curve of Example 1;

[0041] Figure 6 is the near-field electric field distribution diagram of Example 2;

[0042] Figure 7 This is the near-field main beam trajectory fitting curve of Example 2;

[0043] Figure 8 is the near-field electric field distribution diagram of Example 3;

[0044] Figure 9 This is the near-field main beam trajectory fitting curve of Example 3. Implementation Method

[0045] The technical solution of the present invention is described below in conjunction with the accompanying drawings and embodiments.

[0046] This embodiment provides a method for dispersion-free shaping of electromagnetic wave near-field trajectories, including a method for dispersion-free forming a near-field main beam trajectory and a method for dispersion-free focusing a non-diffracted beam.

[0047] The method for forming a near-field main beam trajectory without dispersion comprises the following steps:

[0048] A1. Calculate the involute function C* based on the predetermined shaping trajectory function C.

[0049] The trajectory function C is expressed as:

[0050]

[0051] Among them, x(t), y(t), and z(t) are the parameter expressions of the trajectory function C in the x, y, and z directions with t as the variable, respectively.

[0052] The involute function C* is expressed as:

[0053]

[0054] Where λ is an arbitrary constant, is the unit tangent vector of the trajectory function C, and s is the arc length parameter of the trajectory function C, which is expressed as:

[0055]

[0056] in, To find the first-order derivative of each component in the trajectory function C function expression, t0, a, and b are constants.

[0057] A2. Figure 1 As shown, m units in the array are selected as reference units, denoted as a i (i=1,2,...,m).

[0058] The m reference units can be selected along the longitudinal axis of the array or along the transverse axis of the array. It is only necessary to ensure that the longitudinal coordinates or transverse coordinates of the selected reference units cover the coordinates of all units on the array surface and the coordinate values ​​are not repeated. In this embodiment, the reference units are selected along the transverse axis of the array.

[0059] Over the reference unit a i Draw a tangent line to the trajectory function C, which intersects the involute line C* at p i (i=1,2,...,m); calculate a i With p i The spatial path difference is denoted as l i , then the benchmark unit a i The basic delay compensation coefficient is expressed as:

[0060] τ i =l i / c

[0061] Where c is the propagation speed of electromagnetic waves in free space.

[0062] The non-diffraction beam dispersion-free focusing method comprises:

[0063] like Figure 2 As shown, select n1 units in the array with the same horizontal coordinate as the reference unit a1, and record them as b j1 (j1=1,2,...,n1), calculate b j1 The spatial distance difference with a1 is denoted as ρ j1 ; Select the tilt angle θ0, then the additional delay compensation coefficient of these n1 conventional units is expressed as:

[0064] ν j1 =ρ j1 ×sin(θ0) / c

[0065] Combined with the basic delay coefficient τ1 of the reference unit a1, this n iThe delay compensation coefficient of a conventional unit is expressed as:

[0066] v j1 =ρ j1 ×sin(θ0) / c+τ1

[0067] Similarly, select n2 units in the array with the same horizontal coordinate as the reference unit a2, b j2 (j2=1,2,...,n2), calculate b j2 The spatial distance difference with a2 is denoted as ρ j2 ; Then the delay compensation coefficient of these n2 conventional units is expressed as:

[0068] v j2 =ρ j2 ×sin(θ0) / c+τ2

[0069] Similarly, select the reference unit a in the array m n with the same horizontal axis m Units, b jm (jm=1,2,...,n m ), calculate b jm with a m The spatial path difference is denoted as ρ jm ; then this n m The delay compensation coefficient of a conventional unit is expressed as:

[0070] v jm =ρ jm ×sin(θ0) / c+τ m

[0071] At this point, the calculation of the delay compensation coefficients of all elements in the array antenna is completed.

[0072] The following is an example of the excellent effects of the present invention using actual simulation applications:

[0073] Example 1

[0074] In this embodiment, the array antenna is arranged in a rectangular array, comprising m rows and n columns of units, m = 9, n = 9; the antenna array units are distributed in the yoz plane and radiate toward the +x axis; the selected tilt angle is θ0 = 6°. The array antenna units are dipole antennas, see Figure 3 It can be seen that the standing wave ratio of the dipole antenna is less than 3 and the gain drop is less than 3dB in the frequency range of 280-340GHz, and the operating frequency covers 280-340GHz.

[0075] In this embodiment, the shaping trajectory function C is:

[0076]

[0077] See Figure 4 It can be seen that according to the near-field trajectory dispersion-free shaping method provided by the present invention, the delay compensation coefficient of each antenna unit is obtained, and the delay amount of each unit of the array antenna is controlled based on the delay compensation coefficient. The formed near-field main beam trajectory can perfectly fit the predetermined trajectory function. At the same time, refer to Figure 5 It can be seen that compared with the traditional phase control method, the main beam trajectory formed by the method provided by the present invention does not have the spatial dispersion effect, and the trajectory remains consistent in the range of 280-340GHz.

[0078] Example 2

[0079] In this embodiment, the array antenna is arranged in a rectangular array, and the array includes m rows and n columns of units, where m = 25 and n = 5. The antenna array units are distributed in the yoz plane and radiate toward the +x axis. The selected tilt angle is θ0 = 6°. The array antenna units are dipole antennas.

[0080] In this embodiment, the shaping trajectory function C is:

[0081]

[0082] See Figure 6 It can be seen that according to the near-field trajectory dispersion-free shaping method provided by the present invention, the delay compensation coefficient of each antenna unit is obtained, and the delay amount of each unit of the array antenna is controlled based on the delay compensation coefficient. The formed near-field main beam trajectory can perfectly fit the predetermined trajectory function. At the same time, refer to Figure 7 It can be seen that compared with the traditional phase control method, the main beam trajectory formed by the method provided by the present invention does not have the spatial dispersion effect, and the trajectory remains consistent in the range of 280-340GHz.

[0083] Example 3

[0084] In this embodiment, the array antenna is arranged in a rectangular array, and the array includes m rows and n columns of units, where m = 25 and n = 5. The antenna array units are distributed in the yoz plane and radiate toward the +x axis. The selected tilt angle is θ0 = 6°. The array antenna units are dipole antennas.

[0085] In this embodiment, the shaping trajectory function C is expressed as:

[0086]

[0087] See Figure 8 It can be seen that according to the near-field trajectory dispersion-free shaping method provided by the present invention, the delay compensation coefficient of each antenna unit is obtained, and the delay amount of each unit of the array antenna is controlled based on the delay compensation coefficient. The formed near-field main beam trajectory can perfectly fit the predetermined trajectory function. At the same time, refer to Figure 9 It can be seen that compared with the traditional phase control method, the main beam trajectory formed by the method provided by the present invention does not have the spatial dispersion effect, and the trajectory remains consistent in the range of 280-340GHz.

[0088] In summary, the present invention provides an electromagnetic wave near-field trajectory dispersion-free shaping technology, which is based on the near-field main beam trajectory dispersion-free formation and non-diffraction beam dispersion-free focusing technology. The delay coefficient of each unit of the array antenna is calculated. By controlling the delay of each unit, the main beam can be dispersion-free shaped along a predetermined trajectory function under near-field conditions.

[0089] The above examples are only for the convenience of illustrating the present invention. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention should be regarded as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for shaping electromagnetic wave near-field trajectory without dispersion, characterized in that: Including near-field main beam trajectory dispersion-free forming method and non-diffraction beam dispersion-free focusing method; The dispersion-free near-field main beam trajectory formation method is based on the geometric mapping relationship between the involute and the wavefront of the near-field trajectory function of the electromagnetic wave, and constructs the basic delay compensation coefficient of the array unit through the spatial path difference analytical model between the array reference unit and the trajectory involute; The non-diffracting beam dispersion-free focusing method, combined with the propagation characteristics of the Bessel beam, establishes the additional delay compensation coefficient of the array unit according to the spatial position vectors of the array regular unit and the array reference unit and the beam pointing angle parameters; Based on the basic delay compensation coefficient and the additional delay compensation coefficient, all array elements are delayed accordingly to perform dispersion-free shaping on the main beam, thereby obtaining a main beam with broadband stability.

2. The method for forming an electromagnetic wave near-field trajectory without dispersion according to claim 1, wherein: The method for forming a near-field main beam trajectory without dispersion comprises: A1. Calculate the involute function C* based on the predetermined shaping trajectory function C; A2. Select m units in the array as reference units and record them as a i , i=1,2,...,m; The m reference units are selected along the longitudinal or transverse axis of the array, and the longitudinal or transverse coordinates of the selected reference units must cover the coordinates of all units on the array surface, and the coordinate values ​​are not repeated. Over the reference unit a i Draw a tangent line to the trajectory function C, which intersects the involute line C* at p i ,i=1,2,...,m;calculate a i With p i The spatial path difference is denoted as l i , then the array reference unit a i The basic delay coefficient is expressed as: t i =l i / c Where c is the propagation speed of electromagnetic waves in free space.

3. The method for forming an electromagnetic wave near-field trajectory without dispersion according to claim 2, wherein: The trajectory function C is expressed as: Among them, x(t), y(t), and z(t) are the parameter expressions of the trajectory function C in the x, y, and z directions respectively with t as the variable; The involute function C* is expressed as: Where λ is an arbitrary constant, is the unit tangent vector of the trajectory function C, and s is the arc length parameter of the trajectory function C, which is expressed as: in, To find the first-order derivative of each component in the trajectory function C function expression, t0, a, and b are constants.

4. A method for shaping electromagnetic wave near-field trajectory without dispersion according to claim 2 or 3, characterized in that: The non-diffraction beam dispersion-free focusing method comprises: Select the reference cell a in the array i n with the same horizontal axis i Regular units, denoted as b ji , ji=1,2,...,n i , calculate b ji with a i The spatial path difference is denoted as ρ ji ; Benchmark unit a i The corresponding n i The additional delay compensation coefficient of a conventional unit is expressed as: n' ji =ρ ji ×sin(θ0) / c Where θ0 is any angle in the interval (0°, 90°); Combined with the basic delay coefficient, this n i The delay compensation coefficient of a conventional unit is expressed as: n ji =ρ ji ×sin(θ0) / c+τ i Using the reference unit a i The delay compensation coefficients of the corresponding conventional units are calculated to obtain the delay compensation coefficients of all units in the array antenna.

5. The method for forming an electromagnetic wave near-field trajectory without dispersion according to claim 4, wherein: The electromagnetic wave near-field trajectory dispersion-free shaping method is applicable to a two-dimensional planar array or a three-dimensional curved array; the topological structure of the array includes a rectangular grid, a circular grid or any irregular arrangement.

6. A method for shaping electromagnetic wave near-field trajectory without dispersion according to claim 2 or 3, characterized in that: The antenna form of the array unit is a dipole form, a microstrip patch form, or a composite structure radiator form.

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