A method for calibrating and leveling a transmit-receive channel of a phased array radar antenna

Abstract

The application discloses a kind of methods for calibrating and leveling of phased array radar antenna transceiving channel, the method for calibrating and leveling is based on phased array radar system, the method for calibrating and leveling includes the following steps: step one: setting up radar and horn;Step two: using radar processor to calculate the phase difference of each transceiving channel relative to reference channel;Step three: the obtained multiple phase differences are controlled by the wave control module of antenna unit to be the phase shift value corresponding to each transceiving channel, and whether the phase difference of each transceiving channel and reference channel after phase shift is leveled is verified.The application can not need to purchase to build additional test system, using the frequency source and receiving channel of radar itself and other components to complete the correction and leveling processing of all receiving / transmitting channels in microwave darkroom, with good engineering implementability, it is a kind of high cost performance phased array radar correction and leveling method.

Description

Technical Field

[0001] This invention relates to the field of phased array radar, and specifically to a calibration and balancing method for the transmit and receive channels of a phased array radar antenna. Background Technology

[0002] Phased array radar uses electronic scanning to control the direction of the radar beam to intercept targets in the scanned area. Compared with the previous mechanical radar, it has the advantages of strong multi-target tracking capability, flexible beam pointing, high effective data rate for search and tracking, and high reliability. It is widely used in ground, shipborne and airborne radar systems.

[0003] The electronic scanning function of a phased array radar is achieved by utilizing multiple independent transmit / receive channels on its antenna array. Beam pointing and beamforming are controlled by adjusting the phase shifters and attenuators of these channels. To achieve this, each independent transmit / receive channel of the antenna array must have independent control capabilities; that is, when one channel is transmitting or receiving, the other channels must be switched off. Based on this functionality, the phased array radar needs to perform calibration and balancing on all transmit / receive channels, balancing the transmit and receive phases of all channels.

[0004] Currently, commonly used phased array radar calibration methods include near-field measurement and far-field measurement. Near-field measurement is typically performed indoors, unaffected by outdoor environments or interference signals, but requires a dedicated near-field measurement system, which is costly and difficult to meet the testing requirements of large phased array radars. Far-field measurement is usually performed outdoors, meeting the testing requirements of large phased array radars, but it is susceptible to weather conditions and outdoor interference, requires an additional testing system, and places high demands on the stability and synchronization of the testing system, making engineering implementation difficult. Therefore, this paper proposes a calibration and balancing method for the phased array radar antenna transmit and receive channels. Summary of the Invention

[0005] The technical problem to be solved by this invention is: how to solve the problems that existing calibration and balancing methods are easily affected by weather conditions and outdoor interference, require the construction of additional test systems, have high requirements for the stability and synchronization of the test systems, and are difficult to implement in engineering. This invention provides a calibration and balancing method for the transceiver channel of a phased array radar antenna.

[0006] The present invention solves the above-mentioned technical problems through the following technical solution: the calibration and balancing method of the present invention is based on a phased array radar system, which includes: an antenna unit, a processor, a frequency source, a receiving channel, and a coupler.

[0007] The antenna unit includes multiple transceiver channels and a beam control module. The radio frequency signal output from the frequency source reaches the antenna unit through a coupler. The antenna unit completes the radio frequency signal radiation of a single transceiver channel according to the instructions of the beam control module. The spatial radiation signal received by the horn is injected into the receiving channel through a coaxial cable. At the same time, another radio frequency reference signal coupled out by the coupler is also injected into another receiving channel. The processor processes the two receiving signals simultaneously to obtain the phase difference between the transceiver channel and the reference signal.

[0008] The calibration and balancing method includes the following steps:

[0009] Step 1: Set up the radar and horn. In the microwave anechoic chamber, set up the radar antenna horizontally and set up the horn in the direction of the antenna's physical normal. The distance between the antenna and the horn should be as far as possible while meeting the field conditions of the antenna. The horn should face the antenna, and the radar antenna should be within the coverage area of ​​the horn beam.

[0010] Step 2: Calculate the phase difference between each transmit / receive channel and the reference channel using the radar processor;

[0011] Step 3: The obtained phase differences are controlled by the beam control module of the antenna unit to become the phase shift values ​​of each transceiver channel. Verify whether the phase difference between each transceiver channel and the reference channel is balanced after phase shifting. Add a preset angle to the phase difference between each transceiver channel and the reference channel obtained in Step 2. Control this phase to the phase shifter of each transceiver channel through the beam control module. Process the horn received signal and the reference channel signal simultaneously. The resulting phase difference should be a fixed angle.

[0012] Furthermore, the horizontal installation of the radar antenna in step one is achieved by using a level, with a high-precision circular bubble level placed on the horizontal base of the array.

[0013] Furthermore, the horn is mounted on the normal direction of the antenna's physical normal, which is obtained by a laser plumb line. By adjusting the position of the plumb line, the projection of the vertical laser line on the antenna array surface is basically coincident with the physical horizontal vertical center line of the array surface. The horn mounting position is adjusted so that the projection of the vertical laser line behind the plumb line on the horn is basically coincident with the physical horizontal vertical center line of the horn.

[0014] Furthermore, the phase difference acquisition process in step two is as follows: a radio frequency reference signal output by the frequency source through a coupler is injected into the receiving channel as a reference channel, and the microwave signals radiated by each transceiver channel under controlled conditions are injected into another receiving channel through a horn. The processor processes these two receiving signals simultaneously to obtain the phase difference of each transceiver channel relative to the reference signal.

[0015] Furthermore, in step two, the radio frequency cable connecting the horn and the radar receiving channel is a low differential loss stable phase radio frequency cable, and the connectors at both ends of the cable are tightened using a torque wrench.

[0016] Furthermore, in step two, the frequency source coupled radio frequency signal is injected into the radar receiving channel through a radio frequency cable, and this channel is a reference channel;

[0017] The radio frequency signals radiated by each transceiver channel are received by the speaker and then injected into the receiving channel. This receiving channel and the reference channel are the same module, which ensures that the isolation between the channels is greater than a preset value.

[0018] Since the input signals of these two receiving channels share the same frequency source and the receiving channel circuits are identical, they are insensitive to the frequency drift characteristics of the frequency source and the group delay drift characteristics caused by the temperature of the analog circuit. Furthermore, by simultaneously performing phase difference processing with the reference channel, the effect of insensitivity to group delay drift characteristics can be offset.

[0019] Furthermore, in step two, the operating state of each transceiver channel is controlled by the beam control module. To ensure that there is no correlation or interference between the transceiver channels, when any one transceiver channel is in the transmit state, the other transceiver channels must be in the load state.

[0020] Furthermore, the processor performs sampling, digital down-conversion, digital filtering, coherent accumulation, and phase maximization on the horn-received signal and reference signal of each transceiver channel to obtain the phase difference Δφ between the horn-received signal and the reference signal. i .

[0021] Furthermore, in step three, the phase difference Δφ between each transmit / receive channel and the reference channel... i Based on this, add a fixed angle, Δθ i =Δφ i +90, phase Δθ i The phase shifter of the corresponding transceiver channel is controlled by the beam control module to process the horn received signal and the reference channel signal simultaneously. The resulting phase difference should be a fixed angle, and the balancing error should not exceed ±3°.

[0022] Compared with existing technologies, this invention has the following advantages: the calibration and balancing method for the phased array radar antenna transmit and receive channels does not require the purchase and construction of additional test systems. It utilizes the radar's own frequency source and receiving channels to complete the calibration and balancing of all transmit and receive channels in a microwave anechoic chamber, resulting in low costs for setting up test conditions. Furthermore, this invention can be implemented in a small indoor microwave anechoic chamber, with low requirements for site conditions and no requirements for equipment temperature drift or thermal stability, demonstrating strong engineering feasibility. Moreover, the technology provided by this invention can be used to significantly reduce the cost of near-field or far-field measurement systems required for the standard calibration and balancing of phased array radars, reducing the initial R&D investment for R&D companies and making this method more worthy of widespread adoption. Attached Figure Description

[0023] Figure 1 This is an overall flowchart of the present invention;

[0024] Figure 2 This is a flowchart of the radar system of the present invention. Detailed Implementation

[0025] The embodiments of the present invention are described in detail below. These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.

[0026] like Figure 1 and 2 As shown, this embodiment provides a technical solution: a calibration and balancing method for the transceiver channel of a phased array radar antenna, comprising:

[0027] A calibration and balancing method for the transceiver channels of a phased array radar antenna is disclosed. The phased array radar system includes an antenna element, a processor, a frequency source, a receiving channel, and a coupler. The antenna element contains multiple transceiver channels and a beam control module. The radio frequency (RF) signal output from the frequency source reaches the antenna element via the coupler. The antenna element radiates the RF signal of a single transceiver channel according to the instructions of the beam control module. The spatial radiated signal received by the horn is injected into the receiving channel through a coaxial cable. Simultaneously, another RF reference signal coupled out by the coupler is also injected into another receiving channel. The processor processes the two received signals simultaneously to obtain the phase difference between the transceiver channel and the reference signal.

[0028] Includes the following steps:

[0029] Step 1: Radar and horn setup; In the microwave anechoic chamber, set up the radar antenna horizontally and set up the horn in the direction of the antenna's physical normal. The distance between the antenna and the horn should be as far as possible while meeting the field conditions of the antenna. The horn should face the antenna to ensure that the radar antenna is within the coverage area of ​​the horn beam.

[0030] Step 2: Calculate the phase difference between each transceiver channel and the reference channel using the radar processor; inject one radio frequency reference signal from the frequency source through the coupler into the receiving channel as the reference channel; inject the microwave signal radiated by each transceiver channel in a controlled manner into another receiving channel through the horn; process the two receiving signals simultaneously to obtain the phase difference between each transceiver channel and the reference signal.

[0031] Step 3: The obtained phase differences are controlled by the beam control module of the antenna unit to become the phase shift values ​​of each transceiver channel. Verify whether the phase difference between each transceiver channel and the reference channel is balanced after phase shifting. Add a fixed angle (e.g., 90 degrees) to the phase difference between each transceiver channel and the reference channel obtained in step P2. Control this phase to the phase shifter of each transceiver channel through the beam control module. Process the horn received signal and the reference channel signal simultaneously. The resulting phase difference should be a fixed angle (e.g., 90 degrees).

[0032] In step one, the radar antenna is leveled using a level. A high-precision circular bubble level is placed on the horizontal base of the array, which can achieve an angle leveling capability of 0.05° for both the pitch and roll planes.

[0033] In step one, the horn is mounted in the direction of the antenna's physical normal using a laser plumb line. By adjusting the position of the plumb line, the projection of the vertical laser line on the antenna array surface is made to basically coincide with the physical horizontal vertical center line of the array surface. The horn mounting position is then adjusted so that the projection of the vertical laser line behind the plumb line on the horn is made to basically coincide with the physical horizontal vertical center line of the horn. The accuracy of the laser plumb line is approximately ±1mm / 1m, and it can achieve an angle leveling capability of 0.05°.

[0034] In step two, according to Figure 2 Wiring should be done for the radar system and the horn. Low-loss, phase-stable RF cables should be used as much as possible for the RF cables connecting the horn and the radar receiving channel. The connectors at both ends of the cable should be tightened with a torque wrench to ensure good contact and isolation.

[0035] In step two, the frequency source-coupled radio frequency (RF) signal is injected into the radar receiving channel via an RF cable; this channel serves as the reference channel. The RF signals radiated from each transceiver channel are received by a horn and then injected into the receiving channel. This receiving channel and the reference channel share the same module, ensuring an inter-channel isolation greater than 45 dB. Since the input signals of these two receiving channels share a common frequency source, and the receiving channel circuitry is identical, they are insensitive to frequency source drift characteristics and group delay drift characteristics caused by analog circuit temperature. These effects can be offset by simultaneously performing phase difference processing with the reference channel.

[0036] In step two, the operating status of each transceiver channel is controlled by the beam control module. To ensure that there is no correlation interference between the transceiver channels, when a certain transceiver channel is operating in the transmit state, the other transceiver channels need to operate in the load state.

[0037] In step two, the processor performs sampling, digital down-conversion, digital filtering, coherent accumulation, and phase maximization on the horn-received signal and reference signal of each transceiver channel to obtain the phase difference Δφ between the horn-received signal and the reference signal. i .

[0038] In step three, the phase difference Δφ between each transmit / receive channel and the reference channel is... i Based on this, add a fixed angle (e.g., 90 degrees), Δθ i =Δφ i +90, phase Δθ i The beam control module controls the phase shifter of the corresponding transceiver channel to process the horn-received signal and the reference channel signal simultaneously. The resulting phase difference should be a fixed angle (e.g., 90 degrees), and the balancing error should not exceed ±3° (half the minimum scale value of the phase shifter).

[0039] In this embodiment, taking a Ku-band one-dimensional active phased array radar as an example, the antenna element has 32 independent transmit and receive channels. The phase difference Δφ between the transmitted signals of the 32 transmit and receive channels and the reference signal is measured according to step two. i As shown in Table 1 below:

[0040] Table 1. Phase difference between transmitted signal and reference signal

[0041]

[0042]

[0043] Following step three, the phase difference Δφ of the 32 transmit and receive channels is... i Perform correction and balancing processing to adjust the phase Δθ i The phase shifter of the corresponding transmit / receive channel is controlled by the beam control module. The horn-received signal and the reference channel signal are processed simultaneously to obtain the corrected and balanced fixed phase difference, as shown in Table 2 below:

[0044] Table 2. Correction and balancing of the transmitted signal relative to the reference signal.

[0045]

[0046]

[0047]

[0048] As can be seen from the test results in Table 2, the present invention can perform phased array transceiver channel correction and balancing in a small indoor microwave anechoic chamber with a phase balancing error of ±2.6°, meeting the system requirements of half a phase shifter minimum scale value, and has high practicality and high cost performance.

[0049] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0050] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0051] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for calibrating and leveling a transmit-receive channel of a phased array radar antenna, characterized in that, The calibration and leveling method is based on a phased array radar system, which comprises an antenna unit, a processor, a frequency source, a receiving channel, and a coupler; The antenna unit comprises a plurality of transceiving channels and a wave control module; the radio frequency signal output by the frequency source reaches the antenna unit through the coupler, and the antenna unit completes the radiation of the radio frequency signal of a single transceiving channel according to the instruction of the wave control module, injects the spatial radiation signal received by the horn into the receiving channel through the coaxial cable, and simultaneously injects another radio frequency reference signal coupled and output by the coupler into another receiving channel; the two receiving signals are processed by the processor at the same time to obtain the phase difference of the transceiving channel relative to the reference signal; The calibration and leveling method comprises the following steps: Step one: setting up the radar and the horn; the radar antenna is set up horizontally in the microwave darkroom, and the horn is set up in the physical normal direction of the antenna; the distance between the antenna and the horn should be as far as possible on the basis of meeting the antenna field condition; the horn faces the antenna direction; and the radar antenna should be within the coverage range of the horn beam; Step two: calculating the phase difference of each transceiving channel relative to the reference channel by using the radar processor; Step three: controlling the obtained multiple phase differences through the wave control module of the antenna unit to be the phase shift values of the corresponding transceiving channels, verifying whether the phase differences of the transceiving channels and the reference channel are leveled after phase shifting; adding a preset angle to the phase difference of each transceiving channel relative to the reference channel obtained in step two, and controlling the phase to the phase shifter of each transceiving channel through the wave control module; and simultaneously processing the horn received signal and the reference channel signal, so that the obtained phase difference should be a fixed angle; The phase difference obtaining process in step two is as follows: a radio frequency reference signal coupled and output by the frequency source is injected into the receiving channel as a reference channel; the microwave signal radiated by each transceiving channel is injected into another receiving channel through the horn; and the processor simultaneously processes the two receiving signals to obtain the phase difference of each transceiving channel relative to the reference signal; The frequency source coupled radio frequency signal is injected into the radar receiving channel through the radio frequency cable, and this channel is the reference channel; The radio frequency signal radiated by each transceiving channel is injected into the receiving channel after being received by the horn; this receiving channel and the reference channel are the same module, which ensures that the channel isolation is greater than a preset value; Since the input signals of the two receiving channels are from the same frequency source, and the receiving channel circuits are consistent, the frequency source frequency drift characteristics and the analog circuit temperature induced group delay drift characteristics are not sensitive, and the simultaneous phase difference processing with the reference channel is used to offset the influence of the group delay drift characteristics.

2. The method of claim 1, wherein: The horizontal setting of the radar antenna in step one is realized by using a level; a high-precision circular level bubble is placed on the horizontal base surface of the array.

3. The method of claim 1, wherein: The horn is erected in the normal direction of the physical normal line of the antenna, and the normal line is obtained by a laser plummet. The position of the plummet is adjusted so that the projection of the backward vertical laser line on the horn substantially coincides with the physical horizontal vertical center line of the horn.

4. The method of claim 1, wherein: In step two, the radio frequency cable of the horn and the radar receiving channel is a low-loss stable phase radio frequency cable, and the joints at both ends of the cable are locked by using a torque wrench.

5. The method of claim 1, wherein: In step two, the working states of each transceiving channel are controlled by the wave control module. In order to ensure that there is no irrelevant interference between the transceiving channels, when any one transceiving channel works in the transmitting state, the other transceiving channels need to work in the load state.

6. The method of claim 1, wherein: The processor samples, digitally down-converts, digitally filters, phase-accumulates and takes the maximum value of the horn receiving signal and the reference signal of each transceiving channel, and obtains the phase difference Δφi of the horn receiving signal relative to the reference signal.

7. The method of claim 1, wherein: In step three, a fixed angle Δθi=Δφi+90 is added to the phase difference Δφi of each transceiving channel relative to the reference channel. The phase Δθi is controlled by the wave control module to the phase shifter of the corresponding transceiving channel, and the horn receiving signal and the reference channel signal are simultaneously processed. The obtained phase difference should be a fixed angle, and the error of the balancing requirement should not exceed ±3°.

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