阅读说明：本技术 一种大阵面相控阵天线系统及其校准方法 (Large array plane phased array antenna system and calibration method thereof ) 是由 王德斌 胡斌 刘聪 于 2021-11-23 设计创作，主要内容包括：本发明公开了一种大阵面相控阵天线系统及其校准方法,其中所述校准方法包括：分别计算各个子阵与基准子阵之间的相位差,记为第一相位差；利用光纤延迟线对所述第一相位差进行补偿；分别计算各个子阵内部的相位差,记为第二相位差；利用矢量合成器对所述第二相位差进行补偿；分别计算利用光纤延迟线进行第一相位差补偿后各子阵的实际相位与理论相位之间的相位差,记为第三相位差；利用矢量合成器对所述第三相位差进行补偿。本发明使得光纤延迟线与矢量合成器的最终相位与理论相位贴合,使得大阵面相控阵天线系统大角度扫描时,仍能够保证很好的波束宽度和波束指向。(The invention discloses a large-array-surface phased array antenna system and a calibration method thereof, wherein the calibration method comprises the following steps: respectively calculating the phase difference between each subarray and the reference subarray, and recording the phase difference as a first phase difference; compensating the first phase difference by using a fiber delay line; respectively calculating the phase difference inside each subarray and recording the phase difference as a second phase difference; compensating the second phase difference by using a vector synthesizer; respectively calculating the phase difference between the actual phase and the theoretical phase of each sub-array after the first phase difference compensation is carried out by using the optical fiber delay line, and recording the phase difference as a third phase difference; and compensating the third phase difference by using a vector synthesizer. The invention leads the final phase of the optical fiber delay line and the vector synthesizer to be jointed with the theoretical phase, and can still ensure good beam width and beam pointing when the large array face phased array antenna system scans at a large angle.)

1. A large array surface phased array antenna system is characterized by comprising a plurality of sub-arrays, wherein one sub-array is a reference sub-array;

the subarray is provided with an optical fiber delay line used for compensating a first phase difference, and the first phase difference is the phase difference between the subarray and the reference subarray;

the subarrays are provided with vector synthesizers used for compensating a second phase difference and a third phase difference, the second phase difference is a phase difference inside the subarrays, and the third phase difference is a phase difference between an actual phase and a theoretical phase of each subarray after the first phase difference compensation is carried out by using the optical fiber delay lines.

2. The large-wavefront phased array antenna system of claim 1, wherein the first phase difference is calculated by the formula:

Δφ=360°*24*d*sinθ/λ

in the formula, delta phi is a first phase difference, d is an array element interval, lambda is a wavelength, and theta is an included angle between the antenna beam direction and the normal direction of an antenna array surface.

3. A calibration method applied to the large-wavefront phased array antenna system of claim 1, wherein the calibration method comprises:

respectively calculating the phase difference between each subarray and the reference subarray, and recording the phase difference as a first phase difference;

compensating the first phase difference by using a fiber delay line;

respectively calculating the phase difference inside each subarray and recording the phase difference as a second phase difference;

compensating the second phase difference by using a vector synthesizer;

respectively calculating the phase difference between the actual phase and the theoretical phase of each sub-array after the first phase difference compensation is carried out by using the optical fiber delay line, and recording the phase difference as a third phase difference;

and compensating the third phase difference by using a vector synthesizer.

4. A calibration method according to claim 3, wherein said first phase difference is calculated by:

Δφ=360°*24*d*sinθ/λ

in the formula, delta phi is a first phase difference, d is an array element interval, and lambda is a wavelength.

Technical Field

The invention relates to the technical field of phased array antennas, in particular to a large array plane phased array antenna system and a calibration method thereof.

Background

Recently, phased array antennas have been proposed due to their high beam pointing accuracy and high beam forming speedThe method is widely applied to the fields of radar, communication and the like. Calculating formula theta from phased array antenna beam width_BW=k·λ/（N·d·cosθ₀) It can be seen that when taking a 3dB bandwidth (k = 0.886), for a known wavelength λ, the number of linear elements N is increased, or the element spacing d is increased, if antenna narrow beam scanning is to be achieved. And because the lattice lobe problem needs to be considered in the array element spacing, d generally needs to be less than 0.54 times of lambda, so the method is generally realized by increasing the number N of linear array elements. Therefore, in order to realize a narrow beam design, the phased array antenna needs to add linear array elements, and a large array surface design is selected.

With the increasing requirements on the beam pointing accuracy and beam width of the antenna, the large-array-surface antenna gets more and more attention in various fields. At present, a large array plane is mostly realized by using a distributed antenna array, wherein each subarray works independently. However, after the sub-arrays are installed, the spatial positions of the sub-arrays relative to the target are different, and the delay difference of the output signals of each sub-array needs to be compensated, so that the signals of each sub-array are superposed in phase, and the signal-to-noise ratio of the signals is further improved.

Most of traditional phased-array antennas use a single numerical control phase shifter or a vector synthesizer to complete wave beam control, and the control mode not only limits instantaneous bandwidth, but also improves the phase calibration difficulty among sub-arrays. Therefore, optical fiber delay lines (hereinafter, referred to as delay lines) are also increasingly used in large-wavefront phased array antennas. However, due to the high cost of the delay line, the delay line is generally not used in each array element, but the delay line is controlled among the sub-arrays, and the beam control is completed by using a numerical control phase shifter or a vector synthesizer in the sub-arrays. However, even when the large array surface is scanned at a large angle, the phase difference of each sub-array is still large, so that the beams of the whole antenna surface cannot be completely synthesized, and indexes such as beam width and side lobe are obviously degraded.

Disclosure of Invention

The present invention is directed to overcoming one or more of the deficiencies in the prior art and providing a large-array-plane phased array antenna system and a calibration method thereof.

The purpose of the invention is realized by the following technical scheme: a large array surface phased array antenna system comprises a plurality of sub-arrays, wherein one sub-array is a reference sub-array;

the subarray is provided with an optical fiber delay line used for compensating a first phase difference, and the first phase difference is the phase difference between the subarray and the reference subarray;

the subarrays are provided with vector synthesizers used for compensating a second phase difference and a third phase difference, the second phase difference is a phase difference inside the subarrays, and the third phase difference is a phase difference between an actual phase and a theoretical phase of each subarray after the first phase difference compensation is carried out by using the optical fiber delay lines.

Preferably, the calculation formula of the first phase difference is as follows:

Δφ=360°*24*d*sinθ/λ

in the formula, delta phi is a first phase difference, d is an array element interval, lambda is a wavelength, and theta is an included angle between the antenna beam direction and the normal direction of an antenna array surface.

A calibration method applied to the large-array-surface phased array antenna system includes:

respectively calculating the phase difference between each subarray and the reference subarray, and recording the phase difference as a first phase difference;

compensating the first phase difference by using a fiber delay line;

respectively calculating the phase difference inside each subarray and recording the phase difference as a second phase difference;

compensating the second phase difference by using a vector synthesizer;

respectively calculating the phase difference between the actual phase and the theoretical phase of each sub-array after the first phase difference compensation is carried out by using the optical fiber delay line, and recording the phase difference as a third phase difference;

and compensating the third phase difference by using a vector synthesizer.

Preferably, the calculation formula of the first phase difference is as follows:

Δφ=360°*24*d*sinθ/λ

in the formula, delta phi is a first phase difference, d is an array element interval, and lambda is a wavelength.

The invention has the beneficial effects that:

(1) according to the invention, the phase difference inside the sub-arrays is compensated by using the vector synthesizer, and the phase difference between the sub-arrays is compensated by using the optical fiber delay line, so that the beam control of the whole large array plane phased array antenna system is completed, and a large instantaneous bandwidth is reserved while the high-precision narrow beam control is realized;

(2) according to the invention, the phase difference between the actual phase and the theoretical phase of each sub-array after the first phase difference compensation is carried out by using the optical fiber delay line is compensated, so that the final phase of the optical fiber delay line and the theoretical phase of the vector synthesizer are jointed, and the good beam width and beam pointing can be still ensured when the large array face phased array antenna system scans at a large angle.

Drawings

FIG. 1 is a flow chart of a calibration method of the present invention;

FIG. 2 is a schematic diagram of the phase difference at the four subarray junctions due to the precision of the fiber delay line;

FIG. 3 is a further illustration of the phase difference at the four subarray interfaces due to the precision of the fiber delay line;

fig. 4 is yet another illustration of the phase difference at the four sub-array boundaries due to the precision of the fiber delay line.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive effort based on the embodiments of the present invention, are within the scope of the present invention.

Referring to fig. 1 to 4, the present embodiment provides a large-wavefront phased array antenna system and a calibration method thereof:

example one

A large-array-surface phased array antenna system comprises a plurality of sub-arrays, wherein one sub-array is a reference sub-array. The subarray is provided with an optical fiber delay line used for compensating a first phase difference, and the first phase difference is the phase difference between the subarray and the reference subarray. The subarrays are provided with vector synthesizers used for compensating a second phase difference and a third phase difference, the second phase difference is a phase difference inside the subarrays, and the third phase difference is a phase difference between an actual phase and a theoretical phase of each subarray after the first phase difference compensation is carried out by using the optical fiber delay lines.

Generally, according to the basic principle of a phased array antenna, when an antenna array is used, an equiphase plane perpendicular to the direction of an antenna beam needs to be formed, that is, each antenna unit needs to generate a fixed phase difference according to the direction. In this embodiment, the whole array surface of the large-array-surface phased array antenna is divided into a plurality of sub-arrays, a vector synthesizer is used inside each sub-array to control the phase difference of the antenna units, and the phase difference generated by the central coordinate difference of the factor array is controlled by using the fiber delay line among the sub-arrays.

Specifically, the calculation formula of the first phase difference is as follows:

Δφ=360°*24*d*sinθ/λ

in the formula, Δ Φ is a first phase difference, d is an array element interval, λ is a wavelength, θ is an included angle between an antenna beam direction and an antenna array surface normal direction, taking a one-dimensional array as an example, θ is an azimuth angle, and a value range is-180 to 180 degrees.

The derivation process of the above calculation formula of the first phase difference is: Δ Φ =360 ° f Δ t, without regard to orientation, only the phase difference caused by the interval time; Δ Φ =360 ° 24 × d sin θ/λ is the phase difference that is introduced by the angle and the inter-subarray spacing in the actual case. Where λ is the wavelength, λ = c/f, c is the speed of light (i.e. the speed of electromagnetic wave propagating in space), and Δ t is the time taken for the electromagnetic wave to pass through the 24 array element intervals. Thus Δ Φ =360 ° × f Δ t =360 ° × (c/λ) × Δ t =360 ° × c × Δ t/λ =360 ° × 24 × d sin θ/λ.

In the embodiment, the phase difference inside the sub-arrays is compensated by using the vector synthesizer, and the phase difference between the sub-arrays is compensated by using the optical fiber delay line, so that the beam control of the whole large-array-face phased array antenna system is completed, and a large instantaneous bandwidth is reserved while the high-precision narrow beam control is realized. Meanwhile, the phase difference between the actual phase and the theoretical phase of each sub-array after the first phase difference compensation is carried out by using the optical fiber delay line is compensated, so that the final phase and the theoretical phase of the optical fiber delay line and the vector synthesizer are attached, and the good beam width and beam pointing can be still ensured when the large array face phased array antenna system scans at a large angle.

Example two

As shown in fig. 1, a calibration method applied to the large-wavefront phased array antenna system according to the first embodiment includes:

s1, phase differences between each subarray and the reference subarray are calculated respectively and recorded as first phase differences.

S2, compensating the first phase difference by using an optical fiber delay line.

And S3, respectively calculating the phase difference inside each subarray and recording as a second phase difference.

And S4, compensating the second phase difference by using a vector synthesizer.

And S5, respectively calculating the phase difference between the actual phase and the theoretical phase of each subarray after the first phase difference compensation is carried out by using the optical fiber delay line, and recording as a third phase difference.

And S6, compensating the third phase difference by using a vector synthesizer.

It should be noted that the numbers S1, S2, S3, S4, S5, and S6 are not to be construed as limitations on the order of the steps, and the order of each step may be determined according to actual situations. For example, S3 and S4 may be performed prior to S1 and S2.

The calculation formula of the first phase difference is as follows:

Δφ=360°*24*d*sinθ/λ

in the formula, Δ Φ is a first phase difference, d is an array element interval, λ is a wavelength, θ is an included angle between an antenna beam direction and an antenna array surface normal direction, taking a one-dimensional array as an example, θ is an azimuth angle, and a value range is-180 to 180 degrees.

In the embodiment, the phase difference inside the sub-arrays is compensated by using the vector synthesizer, and the phase difference between the sub-arrays is compensated by using the optical fiber delay line, so that the beam control of the whole large-array-face phased array antenna system is completed, and a large instantaneous bandwidth is reserved while the high-precision narrow beam control is realized. Meanwhile, the phase difference between the actual phase and the theoretical phase of each sub-array after the first phase difference compensation is carried out by using the optical fiber delay line is compensated, so that the final phase and the theoretical phase of the optical fiber delay line and the vector synthesizer are attached, and the good beam width and beam pointing can be still ensured when the large array face phased array antenna system scans at a large angle.

The following describes the embodiment by way of example.

Taking the linear array element number N =96 as an example, the central frequency f of the phased array antenna₀16.3GHz, an instantaneous bandwidth of 500MHz, a cell pitch of 10.4mm, and a maximum scan angle of 30 °. Using a 6-bit fiber delay line, the minimum step is 10ps, represented by the formula Δ φ =360 °/f/Δ t (f refers to the antenna operating frequency, where the substituted value is the antenna center frequency f₀(ii) a Δ t is the interval time, where Δ t =10ps, Δ t depends on the precision of the fiber delay line), it is known that when Δ t =10ps =10 x 10^ (-12) s, f =16.3GHz =16.3 x 10^9Hz, the phase difference Δ Φ =58.68 °, i.e., the phase corresponding to the minimum step of the fiber delay line is 58.68 °.

When the scanning angle is 30 degrees and each sub-array is controlled by independent beams, the sub-array spacing is 24 array element spacing, and the phase difference of the optical fiber delay lines among the sub-arrays is delta phi =360 degrees and 24 x d x sin theta/lambda =2441.088 degrees. The phase of the first array element of each sub-array is called a characteristic phase, and the characteristic phases of the four sub-arrays are respectively 0 °, 2441.088 °, 4882.176 ° and 7323.264 °. At this time, it can be known from actual measurement that the corresponding phase of the optical fiber delay line of the subarray plus the actual phase of the subarray element is not equal to the theoretical phase, and is mainly reflected at the interface of the subarrays, and there is an obvious phase difference, which indicates that the phases between the subarrays of the antenna array are not completely filled, and the phase differences at the interfaces of the four subarrays due to the precision of the optical fiber delay line are as shown in fig. 2, fig. 3, and fig. 4.

The reason for this phenomenon is that the minimum step of the corresponding phase of the fiber delay line is 58.68 °, and therefore, the actual corresponding phases of the four subarray delay lines are 0 °, 2405.88 ° (41 × 58.68), 4870.44 ° (83 × 58.68), and 7276.32 ° (124 × 58.68), respectively, and therefore, after the subarray phase compensation is performed using the fiber delay line, errors, i.e., "remainders" (third phase difference) of 0 °, 35.208 °, 11.736 °, and 46.944 ° occur between the final phase and the theoretical phase.

Therefore, in order to ensure the phase planarity of the whole antenna array, "remainders" are compensated on a vector synthesizer, namely the "remainders" of the sub-array are respectively added on the phases of the array elements. After the 'remainder' compensation is completed, the theoretical phase of the whole array surface is completely consistent with the final phase.

The foregoing is illustrative of the preferred embodiments of this invention, and it is to be understood that the invention is not limited to the precise form disclosed herein and that various other combinations, modifications, and environments may be resorted to, falling within the scope of the concept as disclosed herein, either as described above or as apparent to those skilled in the relevant art. And that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.