A transmit array near field radiation suppression method

Abstract

This invention discloses a method for suppressing near-field radiation from a transmitting array, relating to the fields of measurement, control, and communication. Under the condition of satisfying far-field synthesis of the transmitted signal, this method suppresses near-field radiation quickly and effectively. The method includes: calculating the steering vector of the transmitting antenna array relative to the near-field test point based on the position of each transmitting antenna element and the position of the near-field test point; and using the LCMV algorithm to suppress radiation intensity. This invention can suppress near-field radiation under the condition of satisfying far-field synthesis of the transmitted signal, and the calculation method is fast and effective.

Description

Technical Field

[0001] This invention relates to the fields of measurement and control and communication, and in particular to a method for suppressing near-field radiation from a transmitting array. Background Technology

[0002] Currently, phased array multibeam systems are widely used due to their advantages such as flexible signal processing, fast response speed, ability to handle a large number of targets, and strong scalability. Suppression of near-field signal radiation intensity from phased array transmitters is crucial for the electromagnetic environment and radiation protection of equipment. The characteristic of a transmitter array antenna lies in the difference in signal field strength at the same location caused by the positional differences of its array elements.

[0003] Currently, research on phased array transmitters focuses on far-field signal synthesis. In the far-field condition, the electromagnetic waves emitted by the transmitting antenna elements are considered plane waves at the far-field test point, and the signal strength at that point is calculated by adding the signal amplitudes of each antenna at the far-field test point. However, in the near-field condition, the electromagnetic waves emitted by the transmitting antenna elements cannot be considered plane waves, and the signal strength at that location cannot be calculated by adding the signal amplitudes of each antenna at the near-field test point.

[0004] To ensure that the near-field radiation intensity meets the requirements of equipment and personnel for normal operation over a long period of time, a near-field radiation suppression method needs to be proposed while satisfying the requirements of far-field synthesis of the transmitted signal. Summary of the Invention

[0005] In view of this, the present invention proposes a reasonable and effective method for suppressing near-field radiation. The present invention can suppress near-field radiation while satisfying the requirements of far-field synthesis of the transmitted signal.

[0006] The technical solution adopted in this invention is as follows:

[0007] A method for suppressing near-field radiation from a transmitting array, specifically comprising the following steps:

[0008] Step 1: Based on the position of each transmitting antenna element and the position of the near-field test point, calculate the steering vector of the transmitting antenna array relative to the position of the near-field test point. Use this steering vector as the steering vector of the interference signal and generate a covariance matrix with the steering vector of the far-field signal.

[0009] Step 2: Using the LCMV algorithm, beamforming weights are obtained based on the covariance matrix, and beamforming is performed.

[0010] Furthermore, the specific process of step 1 is as follows:

[0011] ;

[0012] ;

[0013] ;

[0014] In the formula, λ is the operating wavelength of the transmitting antenna, and j is the imaginary unit. Let covariance matrix be the variance matrix. For the first The distance between each transmitting antenna element and the near-field test point; For the first The position of each antenna element ; For the direction of the far-field target, This is the steering vector of the transmitting antenna array relative to the position of the near-field test point. The steering vector for the far-field signal. This represents the number of antenna elements in the transmitting array.

[0015] Furthermore, the beamforming weights in step 2 The calculation formula is as follows:

[0016] ;

[0017] In the formula, The steering vector for the far-field signal. Let be the covariance matrix.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. The phased array near-field radiation suppression method proposed in this invention is not limited by the phased array array type and is applicable to all phased array arrays.

[0020] 2. The phased array emission array near-field radiation suppression method proposed in this invention is simple, accurate, and easy to implement.

[0021] 3. The phased array transmitting array near-field radiation suppression method proposed in this invention can effectively suppress near-field radiation under the condition of far-field synthesis of the transmitted signal. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the far-field target direction of the present invention.

[0023] Figure 2 This is a flowchart of the process of the present invention. Detailed Implementation

[0024] The present invention will be further described below with reference to specific implementation steps:

[0025] This invention provides a near-field radiation suppression method for a transmitting array, referring to... Figure 2 The specific steps include:

[0026] Step 1: Based on the distance between each transmitting antenna element and the near-field test point The steering vector of the transmitting antenna array relative to the position of the near-field test point is calculated. This steering vector is used as the steering vector of the interference signal, and is compared with the steering vector of the far-field signal. Generate covariance matrix .

[0027]

[0028]

[0029]

[0030] In the above formula, For the first The distance between each transmitting antenna element and the near-field test point; For the first The position of each antenna element For the direction of the far-field target, such as Figure 1 As shown in the figure, the black dots represent antenna array elements.

[0031] Step 2: Use the LCMV algorithm to obtain the beamforming weights. This causes the formed beam to create a null at the near-field test point, thus suppressing the radiation intensity.

[0032]

[0033] In addition to the embodiments described above, the present invention may have other implementations. All technical solutions employing equivalent substitutions or transformations fall within the scope of protection claimed by the present invention.

[0034] This embodiment employs an isotropic linear array of 16 equidistant elements, with the element spacing being half a wavelength.

[0035] With the array center as the origin, and arranged at equal intervals along the x-axis, the position of the i-th element is:

[0036]

[0037] Where N=16, and λ is the operating wavelength.

[0038] The near-field test point is located in the array normal direction ( ), located 0.8m from the center of the array.

[0039]

[0040] Distance between each array element and the near-field test point According to the position of the array element With test point location The Euclidean distances are calculated one by one.

[0041] The far-field target direction is set to the array normal direction, meaning the desired signal direction is consistent with the near-field test point direction, and the far-field signal's steering vector... This is the basis for the determination.

[0042] Step 1: Based on the positions of the 16 array elements Location of near-field test point Calculate the distance between each array element and the test point one by one. Generate near-field guidance vector This is used as the steering vector of the interference signal, along with the far-field steering vector. Construct the covariance matrix together .

[0043] Step 2: Solve for beamforming weights using the LCMV algorithm:

[0044]

[0045] This creates a deep null at the near-field test point, thus suppressing near-field radiation.

[0046] After employing the method of this invention, the average power difference between the expected user (far-field target direction) and the near-field interfering user can reach 29.2 dB. Specifically:

[0047] At the user's desired position, the main lobe gain remains good, with a gain loss of only 0.4 dB;

[0048] A deep and precise radiation null was formed at the near-field test point;

[0049] When the expected user is close to the array (e.g., r=0.8 m), the power difference can be further increased to 35.4 dB.

[0050] Compared with existing technologies (conventional maximum directional beamforming schemes), the method of this invention achieves a significant improvement of approximately 18.4 dB in near-field radiation suppression capability, while having almost no impact on the signal synthesis effect in the desired far-field direction, fully verifying the effectiveness and superiority of this invention.

Claims

1. A method for suppressing near-field radiation from a transmitting array, characterized in that, Specifically, the following steps are included: Step 1: Based on the position of each transmitting antenna element and the position of the near-field test point, calculate the steering vector of the transmitting antenna array relative to the position of the near-field test point. Use this steering vector as the steering vector of the interference signal and generate a covariance matrix with the steering vector of the far-field signal. Step 2: Using the LCMV algorithm, beamforming weights are obtained based on the covariance matrix, and beamforming is performed.

2. The near-field radiation suppression method for the transmitting array according to claim 1, characterized in that, The specific process of step 1 is as follows: ； ； ； In the formula, λ is the operating wavelength of the transmitting antenna, and j is the imaginary unit. Let covariance matrix be the variance matrix. For the first The distance between each transmitting antenna element and the near-field test point; For the first The position of each antenna element ; For the direction of the far-field target, This is the steering vector of the transmitting antenna array relative to the position of the near-field test point. The steering vector for the far-field signal. This represents the number of antenna elements in the transmitting array.

3. The near-field radiation suppression method for the transmitting array according to claim 2, characterized in that, Beamforming weights in step 2 The calculation formula is as follows: ； In the formula, The steering vector for the far-field signal. Let be the covariance matrix.

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