Method for realizing polarization control of spatial distribution antenna system radar

Abstract

The invention discloses a method for realizing polarization control of a spatial distribution antenna system radar, a receiving antenna comprises three pairs of six receiving oscillators X1 / Y1, X2 / Y2 and X3 / Y3 which are distributed in a mutually perpendicular and crossed manner, the three mutually parallel antenna oscillators X1, X2 and X3 form a first group, the other three mutually parallel antenna oscillators Y1, Y2 and Y3 form a second group, and phases of the oscillators in the group are synchronous; a digital intermediate frequency technology is adopted, one path of receiving signals is decomposed into two orthogonal digital signals I and Q, one pair of receiving oscillators has two paths of receiving signals X and Y, the two paths of receiving signals X and Y are decomposed into four signals IX, QX, IY and QY, and linear polarization and circular polarization receiving of the pair of receiving oscillators is realized through phase adjustment of the receiving signals; six paths of receiving signals generated by the three pairs of receiving oscillators are divided into two groups according to the parallel direction, the phases of the two groups of receiving signals are synchronously adjusted, linear polarization and circular polarization control of the whole intermediate frequency receiving is achieved, and transmitting and receiving polarization control is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of radar polarization control, and particularly to a method for realizing polarization control of a radar with a spatially distributed antenna system. Background Art

[0002] The radar with a spatially distributed antenna system operates at an intermediate frequency of 2 MHz. As a dedicated device for the middle atmosphere, it is mainly used to detect different physical parameters of the middle atmosphere at 60 - 100 km, including horizontal wind speed / direction, vertical wind speed / direction, wind shear, refractive index structure constant and ionospheric density distribution map, etc. The radar with a spatially distributed antenna system can be divided into two types according to the antenna system: distributed antenna mode and Doppler beam scanning mode. Here, we adopt the distributed antenna mode with separate transmitting and receiving, and the specific composition is as Figure 1 shown. In the figure, the 4 antenna oscillators forming a square are transmitting antennas, and the 6 antenna oscillators of 3 pairs of perpendicular intersections are receiving antennas. The working mode is a separate transmitting and receiving mode of 4 transmitting and 6 receiving. By adjusting the phase relationship of the signals between the antenna oscillators, linear polarization, circular polarization (left-handed circular polarization or right-handed circular polarization) can be generated for transmission and reception.

[0003] By adopting linear polarization for transmission, the horizontal wind speed of the atmosphere can be obtained by calculating the autocorrelation function and cross-correlation function of the linearly polarized received signals of at least 3 antennas. Through fully coherent pulse Doppler processing, the Doppler frequency shift in the vertical direction can be obtained, and thus the vertical wind speed of the atmosphere can be calculated.

[0004] The atmosphere at 60 - 100 km is a rarefied plasma. Due to the action of the geomagnetic field, when electromagnetic waves are incident, double refraction will occur, and the electric waves will be divided into linear polarization and circular polarization (X-wave and O-wave) for propagation. The radar with a spatially distributed antenna system vertically transmits circularly polarized signals upward through the antenna; then receives the reflected signals from the ionosphere through the antenna and measures the amplitude ratio AX / AO of linear polarization and circular polarization. Since the refractive indices of the two polarizations are different and the ionosphere absorbs them differently, using the theory of magnetoplasma, the refractive index structure constant and ionospheric density distribution map can be directly deduced from the amplitude ratio. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, the present invention provides a method for realizing polarization control of a radar with a spatially distributed antenna system, which can achieve transmitting polarization control and receiving polarization control.

[0006] The object of the present invention is achieved through the following technical solutions.

[0007] In a spatially distributed antenna system radar, the receiver uses digital intermediate frequency receiving technology to perform combined processing on received signals for linear polarization and circular polarization (left - hand and right - hand), and can simultaneously generate linearly polarized, circularly polarized (left - hand and right - hand) received signals. By adjusting the excitation signal, linearly polarized, circularly polarized (left - hand or right - hand) transmitted signals can be generated. The polarization modes between the received signals and the transmitted signals can be arbitrarily combined as needed. There are a total of 9 polarization combinations for 3 transmitted polarization signals and 3 received polarization signals.

[0008] The receiving antenna of the spatially distributed antenna system radar consists of 6 antenna elements in 3 pairs of perpendicular intersections. Among them, 3 mutually parallel antenna elements X1, X2, and X3 form the first group with the same phase; the other 3 mutually parallel antenna elements Y1, Y2, and Y3 form the first group with the same phase. In the receiver of the spatially distributed antenna system radar, digital intermediate frequency technology is adopted. One received signal is decomposed into 2 orthogonal digital signals I and Q. One receiving element has 2 received signals X and Y, which are decomposed into 4 signals I X , Q X , I Y , Q Y . By adjusting the phases of the 4 I and Q signals, linearly polarized, circularly polarized (left - hand and right - hand) reception of one receiving element can be achieved. The 6 received signals generated by 3 receiving elements are divided into 2 groups, and after synchronous adjustment, linearly polarized, circularly polarized (left - hand and right - hand) control of the entire radar reception is realized.

[0009] The transmitting antenna of the spatially distributed antenna system radar consists of 4 antenna elements arranged in a square with perpendicularity to each other. One transmitted signal is input to each antenna element. By changing the phase relationship between the 4 transmitted signals, linearly polarized, circularly polarized (left - hand or right - hand) output is achieved. The 4 transmitted signals are driven by 4 excitation signals. By changing the phase relationship of the 4 excitation signals, the polarization control of the transmitted signals can be realized. The transmitted signals of the 4 antenna elements A, B, C, and D are in the same phase to achieve linearly polarized transmission. The transmitted signals of the 4 antenna elements A, B, C, and D are successively advanced by 90° to achieve circularly polarized (left - hand) transmission. The transmitted signals of the 4 antenna elements A, B, C, and D are successively delayed by 90° to achieve circularly polarized (right - hand) transmission. The phase adjustment between the transmitted signals is achieved by adjusting the phases of the corresponding excitation signals in the transmitting branch.

[0010] The quadrature digital I signal and Q signal of the receiving channel can be adjusted for phase advance and phase delay simultaneously. Therefore, linearly polarized, circularly polarized (left - hand and right - hand) signals in intermediate - frequency reception can be generated simultaneously.

[0011] The 3 pairs of receiving elements X1 / Y1, X2 / Y2, and X3 / Y3 perform synchronous calculations according to the processing requirements of linearly polarized reception, left - hand circularly polarized reception, and right - hand circularly polarized reception to form a complete radar received signal.

[0012] The intermediate frequency transmitted signal can only operate in one of the linear polarization or circular polarization (left - hand or right - hand) modes at a certain moment. If both linear polarization and circular polarization (left - hand or right - hand) need to be achieved, it is necessary to alternate in time - sharing. To ensure the quality of the transmitted polarization signal, it is necessary to ensure that the phase difference between the transmission channels does not exceed a certain range, and the measured error does not exceed 1° of the theoretical value.

[0013] The transmitting oscillator and the receiving oscillator are parallel or perpendicular to each other. That is, there are 2 transmitting antenna oscillators parallel to 3 receiving antenna oscillators in two mutually perpendicular directions, and there are a total of 4 transmitting antenna oscillators and 6 receiving antenna oscillators in 2 directions.

[0014] Compared with the prior art, the advantages of the present invention are as follows: Based on changing the polarization mode of the transmitted signal of the space - distributed antenna system radar and accumulating the received signals with different polarization modes, the measurement results of different physical parameters of the middle - layer atmosphere can be obtained through algorithms, including the horizontal wind field, vertical wind field, refractive index structure constant, and ionospheric density distribution map of the middle - layer atmosphere. The present invention is specifically applicable to the occasion of measuring different physical parameters of the middle - layer atmosphere by the space - distributed antenna system radar. Phase modulation is performed on the excitation signals of multiple - path transmission to realize the control of linear polarization and circular polarization (left - hand or right - hand) of the transmitted signal, and phase - shifting processing is performed on the digital intermediate - frequency quadrature signals of multiple - path reception to realize the control of linear polarization and circular polarization (left - hand and right - hand) of the received signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the antenna of the space - distributed antenna system radar of the present invention.

[0016] Figure 2 It is a schematic diagram of the transmission polarization control of the present invention.

[0017] Figure 3 It is a schematic diagram of the reception polarization control - linear polarization of the present invention.

[0018] Figure 4 It is a schematic diagram of the reception polarization control - left - hand polarization of the present invention.

[0019] Figure 5 It is a schematic diagram of the reception polarization control - right - hand polarization of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention will be described in detail below in conjunction with the accompanying drawings of the specification and specific embodiments.

[0021] As Figure 1As shown in the figure, the radar with a distributed antenna space distribution antenna system adopts a separate transmitting and receiving mode. The transmitting antenna consists of 4 transmitting oscillators A, B, C, and D that are perpendicular to each other and distributed in a square. According to the selected intermediate frequency of 2 MHz, the length of each transmitting oscillator is 150 m. The transmitted signal is fed into the center point of the oscillator after being transformed by a balun. The 4 oscillators correspond to 4 transmitted signals P A 、P B 、P C 、P D . The 4 excitation signals of the radar are amplified by 4 power amplifiers to generate 4 transmitted signals P A 、P B 、P C 、P D . By adjusting the phase relationship between the 4 excitation signals, the phase control of the transmitted signal can be achieved, and thus the control of the polarization mode can be realized. Specifically, as shown in Figure 2 : The 4 transmitted signals P A 、P B 、P C 、P D are phase-synchronized to transmit a linearly polarized signal; the phases of the 4 transmitted signals P A 、P B 、P C 、P D decrease by 90° in sequence to transmit a left-handed polarized signal; the phases of the 4 transmitted signals P A 、P B 、P C 、P D increase by 90° in sequence to transmit a right-handed polarized signal.

[0022] As shown in Figure 1 , the receiving antenna consists of 6 receiving oscillators X1 / Y1, X2 / Y2, and X3 / Y3 that are perpendicular and cross-distributed to each other. According to the selected intermediate frequency of 2 MHz, the length of each receiving oscillator is 150 m. Among them, 3 mutually parallel antenna oscillators X1, X2, and X3 form the first group, and the phases of the oscillators within the group are synchronized; the other 3 mutually parallel antenna oscillators Y1, Y2, and Y3 form the second group, and the phases of the oscillators within the group are synchronized; the phases between the 2 groups can be synchronized or not. X1 and Y1 form the first receiving oscillator, X2 and Y2 form the second receiving oscillator, and X3 and Y3 form the third receiving oscillator. The working modes of the 3 receiving oscillators are the same. Therefore, taking the first receiving oscillator X1 / Y1 as an example, the implementation method of different receiving polarizations is described. Oscillator X1 generates digital intermediate frequency quadrature signals I X and Q X , and oscillator Y1 generates digital intermediate frequency quadrature signals I Y and Q Y .

[0023] AsFigure 3 As shown, the digital intermediate frequency quadrature signals I X and Q X generated by oscillator X1 are added to the digital intermediate frequency quadrature signals I Y and Q Y generated by oscillator Y1, that is, calculated according to I = I X +I Y , Q = Q X +Q Y to obtain the digital intermediate frequency quadrature signal I + jQ of the linear polarization reception of this pair of receiving oscillators.

[0024] As Figure 4 shown, the digital intermediate frequency quadrature signals I X and Q X generated by receiving oscillator X1 are delayed by 90° and added to the digital intermediate frequency quadrature signals I Y and Q Y generated by receiving oscillator Y1, that is, calculated according to I = Q X +I Y , Q = -I X +Q Y to obtain the digital intermediate frequency quadrature signal I + jQ of the left-handed polarization reception of this pair of receiving oscillators.

[0025] As Figure 5 shown, the digital intermediate frequency quadrature signals I X and Q X generated by receiving oscillator X1 are advanced by 90° and added to the digital intermediate frequency quadrature signals I Y and Q Y generated by receiving oscillator Y1, that is, calculated according to I = -Q X +I Y , Q = I X +Q Y to obtain the digital intermediate frequency quadrature signal I + jQ of the right-handed polarization reception of this pair of receiving oscillators.

[0026] Three pairs of receiving oscillators X1 / Y1, X2 / Y2, X3 / Y3 are calculated synchronously according to the processing requirements of linear polarization reception, left-handed polarization reception and right-handed polarization reception to form a complete radar receiving signal.

[0027] Since the quadrature digital I signal and Q signal of the receiving channel can be adjusted for phase advance and phase delay simultaneously, the three polarization signals of linear polarization and circular polarization (left-handed and right-handed) in intermediate frequency reception can be obtained simultaneously. Therefore, through different calculations, the horizontal wind speed, vertical wind speed, refractive index structure constant and ionospheric density can be measured. The combinations of different transmitting polarizations and receiving polarizations can be used for data analysis and research and acquisition of new physical quantities.

[0028] The intermediate frequency transmission signal can only work in one of the linear polarization or circular polarization (left-hand or right-hand) modes at a certain moment. If both left-hand polarization and right-hand polarization are to be achieved, they need to be done alternately in time.

Claims

1. A method for realizing polarization control in a spatially distributed antenna system radar, characterized in that: The receiving antenna includes 6 receiving elements X1 / Y1, X2 / Y2, X3 / Y3 that are perpendicularly and crosswise distributed. Among them, 3 mutually parallel antenna elements X1, X2, X3 form the first group, and the phases of the elements within the group are synchronized; the other 3 mutually parallel antenna elements Y1, Y2, Y3 form the second group, and the phases of the elements within the group are synchronized. Using digital intermediate frequency technology, one received signal is decomposed into two orthogonal digital signals I and Q. One receiving dipole has two received signals X and Y, which are decomposed into four signals I X , Q X , I Y , Q Y . By adjusting the phases of the two received signals, linear polarization and circular polarization reception of this receiving dipole are achieved. The six received signals generated by three receiving dipoles are divided into two groups in parallel directions, and the phases of the two groups of received signals are synchronously adjusted to achieve linear polarization and circular polarization control of the entire intermediate frequency reception. The circular polarization includes left-handed polarization and right-handed polarization.

2. A method for implementing polarization control in a spatially distributed antenna system radar according to claim 1, characterized in that: The in-phase digital I signal and Q signal of the receiving channel are simultaneously adjusted for phase synchronization, phase advance, and phase delay, and the linearly polarized, left-hand circularly polarized, and right-hand circularly polarized signals received by the spatially distributed antenna system radar are generated simultaneously.

3. A method for implementing polarization control in a spatially distributed antenna system radar according to claim 1, characterized in that: The 3 receiving elements X1 / Y1, X2 / Y2, X3 / Y3 are synchronously calculated according to the processing requirements of linearly polarized reception, left-hand circularly polarized reception, and right-hand circularly polarized reception to form the complete receiving signal of the spatially distributed antenna system radar.

4. A method for implementing polarization control in a spatially distributed antenna system radar according to claim 1, characterized in that: The transmitting antenna of the spatially distributed antenna system radar includes 4 antenna elements that are perpendicularly and square-distributed. Each antenna element inputs 1 transmitting signal. By changing the phase relationship between the 4 transmitting signals, linearly polarized and circularly polarized transmissions are achieved; the transmitting signals of the 4 antenna elements A, B, C, D are in-phase to achieve linearly polarized transmission, the transmitting signals of the 4 antenna elements A, B, C, D are advanced by 90° in sequence to achieve left-hand circularly polarized transmission, and the transmitting signals of the 4 antenna elements A, B, C, D are delayed by 90° in sequence to achieve right-hand circularly polarized transmission; the phase adjustment between the transmitting signals is achieved by adjusting the phases of the corresponding excitation signals in the transmitting branch.

5. A method for implementing polarization control in a space-distributed antenna system radar according to claim 1, characterized in that: The intermediate-frequency transmitting signal can only operate in one of the linearly polarized or circularly polarized modes at a certain moment. When both linearly polarized and circularly polarized functions need to be achieved, time-sharing operation or alternation is required.

6. A method for realizing polarization control of a spatially distributed antenna system radar according to claim 1, characterized in that: The transmitting elements and receiving elements are parallel or perpendicular to each other, that is, there are 2 transmitting antenna elements parallel to 3 receiving antenna elements in two mutually perpendicular directions.

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