A subarray-level single-pulse phased array antenna system

Abstract

The application discloses a subarray-level single-pulse phased array antenna system and relates to the technical field of phased array radar antennas, comprising an array antenna, a first feed network, a subtracter, a second feed network and a one-dimensional controllable beam forming network. The application realizes the low side lobe characteristics of sum beams, azimuth difference beams and elevation difference beams at the subarray level, has clear architecture, low hardware complexity and can be flexibly expanded in the form of line synthesis.

Description

Technical Field

[0001] This invention relates to the field of phased array radar antenna technology, and more specifically to a subarray-level monopulse phased array antenna system. Background Technology

[0002] In monopulse phased array antennas, it is typically necessary to form sum beams, azimuth difference beams, and elevation difference beams. To reduce sidelobes, Taylor distribution is often used in engineering to form low sidelobes and sum beams, while Bayliss distribution or similar difference beam distributions are used to form low sidelobe difference beams.

[0003] In traditional monopulse phased array antennas, the sum beam, azimuth difference beam, and elevation difference beam often share a single network, making it impossible to simultaneously guarantee low sidelobe characteristics for both the sum and difference beams. One existing approach is to apply independent weights to the three types of beams at the element or subarray level to form low-sidelobe sum and low-sidelobe difference beams, respectively. While this method offers high beamforming freedom, configuring three separate, independent feeding or weighting networks for each type of beam leads to a significant increase in the number of networks, interfaces, insertion loss, and structural complexity. This is especially true in high-frequency antenna systems, where the element-level sum and difference beamforming networks are extremely complex, demanding in terms of space requirements and posing significant engineering challenges.

[0004] Another implementation method of existing technology is to use digital arrays. Such schemes can approximate Taylor, Bayliss or other target amplitude distributions through algorithms, but they usually require more receiving channels, data transmission links and real-time processing resources. The system cost, power consumption, latency and debugging workload are high, and its focus is mostly on weight solving, which may not provide a low-complexity three-beam feeder network structure suitable for engineering implementation.

[0005] Therefore, it is evident that achieving low sidelobe characteristics of sum and difference beams simultaneously without excessively increasing network complexity, hardware costs, and engineering implementation difficulty is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] To address the aforementioned technical challenges, this paper aims to provide a subarray-level monopulse phased array antenna system. This system solves the problem of simultaneously implementing the transmit sum beam Σ, the receive sum beam Σ, the receive azimuth difference beam ΔAZ, and the receive elevation difference beam ΔEL within a subarray-level phased array antenna using a clear architecture with low hardware complexity. Specifically, the azimuth difference beam is formed through a shared sum-weighted network and a summer, while the elevation difference beam is formed through a one-dimensional controllable beamforming network. Furthermore, this architecture possesses scalable row synthesis degrees of freedom.

[0007] This invention is achieved through the following technical solution:

[0008] In a first aspect, a subarray-level monopulse phased array antenna system is provided, comprising an array antenna, a first feed network, a sum and difference device, a second feed network, and a one-dimensional controllable beamforming network, wherein...

[0009] The array antenna consists of multiple subarrays arranged along the azimuth and elevation directions;

[0010] Multiple ports of the first feed network are respectively connected to the multiple subarrays and are configured to give the multiple subarrays a first low sidelobe amplitude distribution during beamforming; the first feed network combines the subarrays located in each quadrant into quadrant ports;

[0011] The sum and difference device is connected to each quadrant port respectively, and the output terminal is provided with a sum port and an azimuth difference port. The sum port is used for time-division transmission and reception, and the azimuth difference port is only used for reception.

[0012] The second feeder network combines one or N rows of subarrays into a row group port along the pitch dimension, where N is an integer ≥ 1;

[0013] The one-dimensional controllable beamforming network includes an amplitude and phase control unit connected one-to-one with each row group port, and a synthesis network that synthesizes the outputs of each amplitude and phase control unit into an elevation difference signal. The amplitude and phase control unit is used to adjust the amplitude and phase of each row group port, and the output of the synthesis network is an elevation difference port, which is only used for receiving signals.

[0014] An optional approach is that each subarray contains multiple radiation channels and a T / R chip, wherein the T / R chip is used for amplitude and phase compensation, scanning phase configuration and channel consistency processing of the radiation channels within the subarray; the first feed network and the second feed network are used to implement subarray-level target weighting.

[0015] An alternative approach is that the amplitude distribution of the first low sidelobe is a two-dimensional Taylor distribution.

[0016] An alternative approach is that the amplitude and phase control unit is a channel of the amplitude and phase multifunction chip, used to control the amplitude and phase of the received signal.

[0017] An alternative approach is that N equals 1, and the second power supply network combines each row of subarrays into a row group port, with each row group port corresponding to an amplitude and phase control unit.

[0018] An alternative approach is that, where N≥2, the second power supply network combines multiple subarrays into a single row group port through an unequal power combining network, and then connects it to an amplitude and phase control unit.

[0019] An alternative approach is that the unequal power combining network is used to combine two or more rows of subarrays into a row group port according to the amplitude ratio between corresponding rows in the amplitude distribution of the target low sidelobe difference beam.

[0020] An alternative approach is to use a Bayliss distribution or its engineering approximation distribution for the one-dimensional controllable beamforming network to achieve a one-dimensional low sidelobe difference beam distribution.

[0021] An optional solution includes a frequency conversion module. When receiving, the frequency conversion module down-converts the three radio frequency signals from the sum port, azimuth difference port, and elevation difference port to intermediate frequencies, and transmits them to the signal processing module respectively. When transmitting, the frequency conversion module up-converts the intermediate frequency signal from the signal processing module to a radio frequency signal and feeds it into the sum port of the sum and difference device.

[0022] An alternative approach is to further include a signal processing module, which is used to generate beam control commands and process the intermediate frequency signal from the frequency conversion module.

[0023] An optional solution includes a beamforming control and power supply module, which is used to send beam control commands to the array antenna and the one-dimensional controllable beamforming network, and to provide DC power.

[0024] An optional scheme is that the first power supply network is an unequal power splitting network or an unequal power combining network, and its power splitting ratio or power combining ratio is determined according to the amplitude distribution of the first low sidelobe.

[0025] An alternative approach is that the amplitude phase control unit is configured to give the line group ports located on the upper and lower sides of the pitch centerline the phase relationship required to form the pitch difference beam.

[0026] The subarray-level monopulse phased array antenna system of the present invention has the following advantages and beneficial effects compared with the prior art: 1. By simultaneously serving the sum beam Σ and the azimuth difference beam ΔAZ through the first feed network, the independent azimuth difference weighting network is reduced, greatly reducing the system complexity. 2. The azimuth difference is generated by the sum-difference generator, with a clear structure and stable phase relationship, suitable for cooperation with quadrant synthesis feed networks. 3. The elevation difference is generated separately through the second feed / one-dimensional controllable beamforming network, so that the low sidelobe amplitude and phase distribution of the elevation difference is not directly limited by the Taylor weights of the sum path. 4. It has the highest degree of control freedom when one row has one row group port; when N rows are synthesized into one row group port, the number of amplitude and phase chip channels can be reduced, and the amplitude distribution design capability can be retained through unequal power combining. 5. It simultaneously achieves low sum sidelobes and elevation difference sidelobes, greatly improving the anti-clutter interference capability. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0028] Figure 1 This is a schematic diagram of the overall structure of a subarray-level monopulse phased array antenna system according to an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the structure of a one-dimensional controllable beamforming network according to an embodiment of the present invention;

[0030] Figure 3 This is a logic connection diagram of a phase control unit where N equals 1 according to an embodiment of the present invention;

[0031] Figure 4 This is a logic connection diagram of the N≥2 phase control unit according to an embodiment of the present invention;

[0032] Figure 5 The above are simulation results of the pitch difference pattern according to an embodiment of the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0034] Definitions:

[0035] Taylor distribution (also known as Taylor line source distribution or Taylor amplitude distribution) is a aperture amplitude-weighted distribution used for antenna arrays.

[0036] The Bayliss distribution (also known as the Bayliss difference beam distribution or Bayliss distribution) is a aperture amplitude-weighted distribution specifically used for difference beam patterns.

[0037] Example

[0038] like Figure 1-5As shown, the subarray-level monopulse phased array antenna system provided in this embodiment involves phased array antennas and monopulse angle measurement technology. It is a phased array antenna structure that implements three types of beams at the subarray level: a shared transmit / receive sum beam Σ, a receiving azimuth difference beam ΔAZ, and a receiving elevation difference beam ΔEL. This antenna system can be used for target search, target tracking, monopulse angle measurement, precise pointing, and other array systems requiring low sidelobe sum and difference beams. The sum beam Σ is used for both transmission and reception, employing a time-division multiplexing operation; the azimuth difference beam ΔAZ and the elevation difference beam ΔEL are only used for receiving angle measurement. The transmit link only uses the sum beam Σ, and does not use the azimuth difference beam ΔAZ and the elevation difference beam ΔEL.

[0039] The subarray-level monopulse phased array antenna system provided in this embodiment includes an array antenna, a first feed network, a sum and difference device, a second feed network, a one-dimensional controllable beamforming network, a beamforming control and power supply module, a frequency conversion module, and a signal processing module. For example... Figure 1 As shown, the main components of the system and their interconnections are presented.

[0040] An array antenna consists of multiple subarrays arranged along the azimuth and elevation directions. Subarrays can be divided by quadrant, row, column, or subarray group.

[0041] Each subarray contains multiple radiation channels and T / R chips. The T / R chips are used for amplitude and phase compensation, scanning phase configuration, and channel consistency processing of the radiation channels within the subarray. The first and second feed networks are used to implement subarray-level target weighting. The T / R chips are located within the subarray and are used for amplitude and phase compensation, scanning phase configuration, and channel compensation of each radiation channel. T / R chips are not the only means of implementing three-beam subarray-level target weighting.

[0042] The first feed network has multiple ports that are connected one-to-one with multiple subarrays and is configured to give the multiple subarrays a first low sidelobe amplitude distribution when forming and beamforming; the first feed network combines the subarrays located in each quadrant into quadrant ports.

[0043] The sum and difference devices are connected to the ports of each quadrant respectively. The output terminal is equipped with a sum port and an azimuth difference port. The sum port is used for time-division multiplexing of transmission and reception, while the azimuth difference port is only used for reception.

[0044] The first feed network is connected to multiple subarrays and configured to give the subarrays a first low sidelobe amplitude distribution on the sum beam channel. Preferably, the first low sidelobe amplitude distribution can be a two-dimensional Taylor distribution. The first feed network synthesizes into multiple quadrant ports in multiple quadrants, and the multiple quadrant ports are connected to a sum and difference device. The sum port Σ of the sum and difference device outputs the sum beam, and the azimuth difference port ΔAZ outputs the azimuth difference beam. The sum port Σ is a shared port for transmission and reception, and transmission and reception operate in time division; the azimuth difference port ΔAZ is only used for receiving angle measurement. In this embodiment, four quadrants are used.

[0045] The first feed network is a weighted feed network shared by the sum beam Σ and the azimuth difference beam ΔAZ. It can be a waveguide unequal power divider network, or a microstrip, stripline, or other passive feed structure. The sum and difference converter is connected to multiple quadrant ports formed by the first feed network to generate the sum Σ and azimuth difference ΔAZ.

[0046] The first power supply network can be an unequal power distribution network or an unequal power combining network, and its power distribution ratio or power combining ratio is determined according to the amplitude distribution of the first low sidelobe.

[0047] The second feed network combines one or N rows of subarrays into a single row port along the elevation dimension, where N is an integer ≥ 1. The second feed network is used for subarray row combining in the elevation direction, and the combined subarrays are then fed into a one-dimensional controllable beamforming network. For example... Figure 2 As shown, the structure of a one-dimensional controllable beamforming network for pitch difference is illustrated. One or N rows of beams are synthesized and connected to amplitude and phase control ports, then the network is used to form a ΔEL. Each amplitude and phase control port adjusts the amplitude to achieve the low-difference sidelobe distribution in the pitch dimension, and adjusts the phase to achieve the difference beam phase relationship between the upper and lower half-arrays.

[0048] A one-dimensional controllable beamforming network includes amplitude and phase control units connected one-to-one with each row group port, and a combining network that synthesizes the outputs of each amplitude and phase control unit into an elevation difference signal. The amplitude and phase control units are used to adjust the amplitude and phase of each row group port, and the output of the combining network is the elevation difference port, which is only used for reception. The amplitude and phase control units can be ports or channels in an amplitude and phase multifunction chip, used for amplitude and phase control of the received signal. The amplitude and phase multifunction chip has multiple ports or channels.

[0049] The amplitude phase control unit can be configured to give the line group ports located on the upper and lower sides of the pitch centerline the phase relationship required to form the pitch difference beam.

[0050] A one-dimensional controllable beamforming network is set along the pitch dimension and consists of a second feed network, an amplitude and phase control unit, and a combining network. This network can be an active beamforming network or a controllable network composed of a passive horizontal combining network and an amplitude and phase multifunctional chip.

[0051] The second feed network and the one-dimensional controllable beamforming network are used to form the elevation difference port ΔEL. The second feed network combines one or N rows of subarrays along the elevation dimension into a single row group port, which is connected to an amplitude-phase multifunction chip or an equivalent amplitude-phase control unit. Multiple amplitude-phase control ports, after amplitude and phase control, are then combined by a combining network into the elevation difference port ΔEL. The elevation difference port ΔEL is used only for receiving angle measurements. The one-dimensional controllable beamforming network is used to receive the elevation difference beam ΔEL. It is combined in one or N rows and connected to the amplitude-phase control port. Through the amplitude-phase multifunction chip or equivalent amplitude-phase control unit, a one-dimensional low sidelobe difference beam distribution is achieved, and multiple amplitude-phase controlled elevation dimension ports are combined into a single elevation difference port ΔEL.

[0052] When N equals 1, the second feed network combines each row of subarrays into a single row group port, with each row group port connected to an amplitude-phase control unit. This method offers the highest degree of freedom and is suitable for schemes with sufficient amplitude-phase multifunction chip channels and high requirements for pitch difference sidelobe performance. When N ≥ 2, the second feed network combines multiple rows of subarrays into a single row group port via an unequal power combining network, which is then connected to an amplitude-phase control unit. The unequal power combining network is used to combine two or more rows of subarrays into a single row group port according to the amplitude ratio between corresponding rows in the target low sidelobe difference beam amplitude distribution.

[0053] In the implementation with the highest degree of freedom, each row of subarrays is combined into a row group port. This row group port connects to a port or channel of the amplitude-phase multifunction chip, allowing for independent setting of amplitude and phase for each row, facilitating low-difference sidelobe distribution. When the number of channels in the amplitude-phase multifunction chip is insufficient or the system needs to reduce the number of channels, two or more rows can be first combined into a row group port via an unequal-splitting power combining network before connecting to the amplitude-phase multifunction chip port. In this case, the relative amplitudes between the combined rows can be determined by the unequal-splitting power combining network, and the overall amplitude and phase of the combined row group port are then adjusted by the amplitude-phase control unit. This unequal-splitting power combining network is used to pre-achieve a partial target amplitude distribution during the multi-row combining stage. Figure 3 The diagram shown illustrates the design with one amplitude and phase control port per row, used to explain the highest degree of freedom. Figure 4 The diagram shown illustrates the connection of multiple unequal power combining lines to a single amplitude and phase control port. This design is used to explain the expansion design when the number of channels is insufficient. In the diagram, j can be 1 or an integer greater than 1. When combining multiple lines, a single-level or multi-level unequal power combining network can be used. The multi-line combining network can use unequal power combining to pre-realize the amplitude ratio within the group, thereby reducing the number of control channels while retaining the component's amplitude adjustment capability.

[0054] The beamforming control and power supply module receives beam control commands from the signal processing module and sends them to the array antenna and the one-dimensional controllable beamforming network, while providing DC power to the array antenna and the one-dimensional controllable beamforming network.

[0055] The frequency conversion module is connected between the azimuth port, the elevation port, the pitch port, and the signal processing module. It is used to downconvert signals from each port during reception and upconvert signals from the signal processing module during transmission.

[0056] When the frequency conversion module is receiving, it down-converts the three radio frequency signals (sum, azimuth difference, and elevation difference signals) from the sum port, azimuth difference port, and elevation difference port to intermediate frequency, and transmits them to the signal processing module for direct acquisition and processing. When transmitting, it up-converts the intermediate frequency signal from the signal processing module to radio frequency signal, feeds it into the sum port of the sum and difference converter, and distributes it to each antenna subarray through the first feed network, and radiates it into free space by the array antenna.

[0057] One-dimensional controllable beamforming networks can employ a Bayliss distribution or its engineering approximation to achieve a one-dimensional beam distribution with low sidelobe difference.

[0058] The signal processing module generates beam control commands and processes the intermediate frequency signals from the frequency converter module. The signal processing module is responsible for both signal processing and beam control.

[0059] This embodiment employs two weighted networks to handle different beamforming tasks. The first weighted network serves the azimuth beam Σ and the azimuth difference beam ΔAZ, while the second weighted network serves the elevation difference beam ΔEL. This division of labor avoids setting up completely independent networks for each of the three beams, while preserving the amplitude and phase control degrees of freedom required for low sidelobe design of the elevation difference beam.

[0060] System working process

[0061] During transmission, the signal enters the sum-difference converter from the sum port Σ, passes through multiple quadrant ports to the first feed network, and is then distributed to each subarray according to the target low sidelobes and beam amplitude distribution. The transmission link only uses the sum port Σ.

[0062] During the reception and beamforming process, the received signals from each subarray are combined in the quadrant via the first feed network, enter the summer through multiple quadrant ports, and are output from the summer port Σ as the received and beamforming signals.

[0063] When receiving the azimuth difference beam, the received signals of each subarray still pass through the first feed network and quadrant port, and the summer outputs the azimuth difference signal from the azimuth difference port ΔAZ according to the azimuth difference combination relationship.

[0064] When receiving the elevation difference beam, the subarray signals of each row or multiple row groups are combined into multiple amplitude and phase control port output signals through the second feed network. The signals of each port are then combined into the elevation difference signal ΔEL by the combining network after amplitude and phase control. The transmit and receive signal flow diagram shown in the table below shows that the transmitter only uses the Σ port, while the receiver uses the Σ, ΔAZ, and ΔEL ports.

[0065] emission Sum and Difference Device → First Feed Network → Antenna Array Σ Transmission and Beam Receive and Antenna array → First feed network → Sum and difference device Σ Receive detection / tracking Azimuth difference Antenna array → First feed network → Sum and difference device ΔAZ Receiver azimuth angle measurement pitch difference Antenna array → Second feed network → Amplitude and phase control → Synthesizing network ΔEL Receive pitch angle measurement

[0066] The pitch difference one-dimensional controllable beamforming network sets the amplitude and phase of each row group port to ensure that the pitch dimension amplitude and phase distribution meets the requirements of low sidelobe difference beamforming.

[0067] like Figure 5 The image shows a comparison of the radiation pattern simulation results for the pitch difference beam under Bayliss weighting and Taylor weighting. The sidelobe level of the pitch difference beam under Bayliss weighting is significantly lower than that under Taylor weighting, and the descent rate from the double peak to the first sidelobe is significantly increased, significantly improving the anti-clutter interference capability. Low sidelobes and beamforming are achieved using a Taylor distribution through the first feed network, while low-sidelobe pitch difference beamforming is achieved using a Bayliss distribution through a one-dimensional controllable beamforming network. Since both are no longer directly constrained by the same set of fixed weights, it is easier to optimize the sidelobe performance of the pitch difference beam and the pitch difference beam separately.

[0068] The first and second feed networks can be waveguides, microstrip lines, striplines, coaxial cables, or LTCC networks. The sum and difference network can be a magic T, hybrid ring, 3dB bridge, 180-degree mixer, or other equivalent sum and difference network. The one-dimensional controllable beamforming network can employ an amplitude-phase multifunction chip, or other amplitude-phase control modules or active beamforming components. The elevation difference ports can be synthesized in one, two, or multiple rows of subarrays, and the synthesis method can be equally or unequally divided, preferably determined based on the target low sidelobe difference beam distribution. The preferred low sidelobe sum and difference beam distribution is Taylor, and the preferred low sidelobe difference beam distribution is Bayliss, but other low sidelobe sum and difference beam / beam distributions are also acceptable.

[0069] In this embodiment, two weighted networks are used: the first feed network is used for the sum beam Σ and the azimuth difference beam ΔAZ, and the second feed / one-dimensional controllable beamforming network is used for the elevation difference beam ΔEL. The azimuth difference beam ΔAZ is generated by the quadrant ports formed by the first feed network via a summer, without the need for a separate, independent azimuth difference active network. For the one-dimensional controllable elevation difference beamforming, the elevation difference ΔEL is synthesized to the amplitude and phase control port through one or N rows, and then the amplitude and phase control and synthesizing network forms a low sidelobe difference beam. Row synthesis is scalable, with each row having one row group port offering the highest degree of freedom; synthesizing two or more rows into one row group port can reduce the number of channels, and unequal power combining can be used for multi-row synthesis to meet amplitude distribution requirements.

[0070] Example:

[0071] The first feed network and the summator form Σ and ΔAZ.

[0072] The array antenna is divided into multiple subarrays according to the azimuth and elevation directions. The first feed network connects the multiple subarrays and distributes the amplitude to each subarray according to a two-dimensional Taylor distribution or other first low sidelobe amplitude distribution. The first feed network synthesizes quadrant ports in each quadrant, for example, synthesizing them into a first quadrant port, a second quadrant port, a third quadrant port, and a fourth quadrant port.

[0073] Four quadrant ports are connected to a summer. The sum port Σ of the summer is used for both transmission and reception, operating in a time-division multiplexing manner; the azimuth difference port ΔAZ is used only for receiving angle measurements. During transmission, the signal is input through the Σ port, distributed to each subarray via the summer, quadrant ports, and the first feed network. During reception, the received signal from the subarray passes through the first feed network and the summer, and is output as the received sum signal and azimuth difference signal through the Σ port and ΔAZ port, respectively. In this example, the first feed network can be an unequally divided waveguide power divider network. Its power division ratio is determined based on the sum beam target amplitude distribution. Preferably, the sum beam target amplitude distribution is a two-dimensional Taylor distribution. Since the azimuth difference ΔAZ is formed after entering the summer from the same set of quadrant ports, a separate independent weighting network is not required for the azimuth difference path.

[0074] One-dimensional controllable beamforming for the elevation difference of one row group port per row

[0075] The second feed network has multiple row group ports along the elevation dimension. Each row of subarrays is first combined into a row group port via the feed / combining structure within that row. Each row group port connects to a port or channel of the amplitude-phase multifunction chip (APFMCC). The APFMCC independently sets the amplitude and phase for each row group port, resulting in a Bayliss distribution or other low sidelobe difference beam distribution in the elevation dimension. The advantage of this example is its high degree of freedom, allowing independent control of each row, making it suitable for scenarios with a sufficient number of APFMCC channels and high requirements for elevation difference sidelobe performance. In this example, the second feed network can first combine multiple subarrays within the same row in the azimuth direction, so that each row corresponds to a row group port. These multiple row group ports are arranged along the elevation direction and connected to multiple ports of the APFMCC. The APFMCC sets the amplitude of each row group port according to the elevation difference beam distribution, ensuring that the row group ports located above and below the elevation centerline have the phase relationship required for the difference beam. If the Bayliss distribution is used, the amplitude of each row group port can be set according to the Bayliss weights; if other low sidelobe difference beam distributions are used, they can also be set according to the target distribution.

[0076] One-dimensional controllable beamforming by combining N rows into a single row group port for elevation difference.

[0077] When the number of channels in the amplitude-phase multifunction chip is insufficient, or when the system aims to reduce the number of control ports, two or more rows of subarrays can be combined into a single row group port, which is then connected to a port of the amplitude-phase multifunction chip. When combining two or more rows, an unequal-splitting power combiner network can be used, ensuring that each row has already acquired a portion of the target amplitude distribution before combining. For example, if two rows of subarrays are combined into a single row group port, the relative amplitude between the two rows can be determined by the unequal-splitting power combiner; the overall amplitude and phase of this port are then controlled by the amplitude-phase multifunction chip. This reduces the number of chip channels while retaining a certain level of low sidelobe difference beam design capability. In this example, N can be 2 or an integer greater than 2. The value of N can be determined based on the number of available channels in the chip, the number of array rows, the target sidelobe index, and the allowable beam error. After multi-row combining, the amplitude-phase control unit controls the equivalent amplitude and phase of the combined multi-row array. To improve the amplitude distribution approximation accuracy, a multi-stage unequal-splitting power combiner structure can be used within the multi-row combining network.

[0078] Transmit time division and receive angle measurement process

[0079] Transmission phase: The transmission signal is input from the Σ port, distributed to multiple quadrant ports by the sum and difference device, and then distributed to each subarray by the first feed network to form low sidelobe transmission and beam.

[0080] Reception and beamforming stage: The array receives the signal and outputs the received signal at the Σ port after passing through each subarray, the first feed network and the summator.

[0081] Azimuth difference receiving stage: The array receives the signal and outputs the azimuth difference signal at the ΔAZ port through the first feed network and the summator, which is used for azimuth direction single pulse angle measurement.

[0082] Pitch difference reception stage: The array receives the signal and outputs the pitch difference signal at the ΔEL port through the second feed network and the one-dimensional controllable beamforming network, which is used for pitch direction single pulse angle measurement.

[0083] Angle measurement stage: The receiver or signal processing unit performs single-pulse amplitude / phase comparison angle measurement based on the three received signals Σ, ΔAZ, and ΔEL.

[0084] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A subarray-level monopulse phased array antenna system, characterized in that, It includes an array antenna, a first feed network, a sum and difference device, a second feed network, and a one-dimensional controllable beamforming network, wherein, The array antenna consists of multiple subarrays arranged along the azimuth and elevation directions; Multiple ports of the first feed network are respectively connected to the multiple subarrays and are configured to give the multiple subarrays a first low sidelobe amplitude distribution during beamforming; the first feed network combines the subarrays located in each quadrant into quadrant ports; The sum and difference device is connected to the ports of each quadrant, and the output terminal is provided with a sum port and an azimuth difference port. The sum port is used for time-division transmission and reception, and the azimuth difference port is only used for reception. The second feeder network combines one or N rows of subarrays into a row group port along the pitch dimension, where N is an integer ≥ 1; The one-dimensional controllable beamforming network includes an amplitude and phase control unit connected one-to-one with each row group port, and a synthesis network that synthesizes the outputs of each amplitude and phase control unit into an elevation difference signal. The amplitude and phase control unit is used to adjust the amplitude and phase of each row group port, and the output of the synthesis network is an elevation difference port, which is only used for receiving signals.

2. The subarray-level monopulse phased array antenna system as described in claim 1, characterized in that, Each of the subarrays contains multiple radiation channels and a T / R chip, wherein the T / R chip is used for amplitude and phase compensation, scanning phase configuration and channel consistency processing of the radiation channels within the subarray; The first and second feeding networks are used to implement subarray-level target weighting.

3. The subarray-level monopulse phased array antenna system as described in claim 1, characterized in that, The first power supply network is an unequal power splitting network or an unequal power combining network, and its power splitting ratio or power combining ratio is determined according to the amplitude distribution of the first low sidelobe; the amplitude distribution of the first low sidelobe is a two-dimensional Taylor distribution or its engineering approximation distribution.

4. The subarray-level monopulse phased array antenna system as described in claim 1, characterized in that, The amplitude and phase control unit is a port or channel of the amplitude and phase multifunction chip, used to control the amplitude and phase of the received signal, and is configured to give the ports located on the upper and lower sides of the pitch centerline the phase relationship required to form the pitch difference beam.

5. The subarray-level monopulse phased array antenna system as described in claim 1, characterized in that, The N is equal to 1, and the second power supply network combines each row of subarrays into a port, with each port corresponding to an amplitude and phase control unit.

6. The subarray-level monopulse phased array antenna system as described in claim 1, characterized in that, If N is greater than or equal to 2, the second feed network combines multiple rows of subarrays into one port through an unequal power combining network, and then connects it to an amplitude and phase control unit; the unequal power combining network is used to synthesize the multiple rows of subarrays according to the amplitude ratio between corresponding rows in the amplitude distribution of the target low sidelobe difference beam.

7. The subarray-level monopulse phased array antenna system as described in claim 1, characterized in that, The one-dimensional controllable beamforming network adopts a Bayliss distribution or its engineering approximation to achieve a one-dimensional low sidelobe difference beam distribution.

8. The subarray-level monopulse phased array antenna system as described in claim 1, characterized in that, It also includes a frequency conversion module, which downconverts the three radio frequency signals from the sum port, azimuth difference port and elevation difference port to intermediate frequency when receiving; and upconverts the signal to be transmitted into a radio frequency signal when transmitting and feeding it into the sum port of the sum and difference device.

9. The subarray-level monopulse phased array antenna system as described in claim 1, characterized in that, It also includes a signal processing module and a beamforming control and power supply module. The signal processing module is used to generate beam control commands and process the received signals from the sum, azimuth, and elevation difference ports. The beamforming control and power supply module is used to send beam control commands to the array antenna and the one-dimensional controllable beamforming network and provide DC power.

10. The subarray-level monopulse phased array antenna system as described in claim 1, characterized in that, The first and / or second feed network is a waveguide, microstrip, stripline, coaxial, or LTCC network; the sum and difference device is a magic T, hybrid ring, 3dB bridge, 180-degree mixer, or equivalent sum and difference network.

Images