Ultra-low sidelobe dual-polarization active row feed array with variable unit number and unequal power division

Abstract

The invention relates to an ultra-low side lobe row feed array. The main types of current engineering include a traveling wave waveguide array and passive row feed with unequal power division feed. Due to the existence of an azimuth frequency scanning angle, zenith scanning blind spots exist, the larger the frequency deflection angle is, the larger the scanning dome blind area is, and azimuth beams are fixed, so that multiple beams cannot be formed; although the beam points to the normal direction, the defect of large loss exists. Aiming at the defects in the prior art, the invention provides the ultra-low side lobe dual-polarization active row feed array with variable unit number and unequal power division, a form based on an unequal unit active subarray is adopted, dual-polarization active row feed is realized, and the ultra-low side lobe dual-polarization active row feed array has the characteristics of ultra-low side lobe, low cost and low loss.

Description

Technical Field

[0001] Weather radar is an effective monitoring device for disastrous weather. Traditional weather radar has gone through three stages: analog, digital, and Doppler. The new generation of weather radar is developing towards dual polarization and phased array systems. Sidelobe level is an important indicator of the weather radar array subsystem. On the one hand, the use of ultra-low sidelobe technology can greatly improve the overall performance of the weather radar. On the other hand, how to effectively reduce costs while maintaining high performance is also a focus of practical engineering applications. Based on the need to save costs, the phased array composed of line-fed arrays with elevation phase scanning and azimuth machine scanning is a common form of meteorological radar. It relies on fixed amplitude weighting to achieve ultra-low sidelobes in azimuth, and uses unit-level digitization in the elevation direction to achieve ultra-low sidelobes through high-precision digital amplitude modulation. Regarding ultra-low sidelobe line-fed arrays, the main types in engineering are currently traveling waveguide arrays and passive line feeds with unequal power division feeding. Among them, the traveling waveguide array achieves low sidelobe amplitude weighting by opening gaps with different angles or different widths and depths on the narrow side of the waveguide. The terminal is connected to a matching load, which can match well in a wider frequency band; the passive line feed with unequal power division feeding uses a power division network composed of unequal power dividers to achieve corresponding power distribution for the entire row of antenna units. These types of arrays have their own advantages and are adopted by meteorological radars for different purposes. However, they also have certain disadvantages. For example, the former has a zenith scanning blind spot due to the existence of an azimuth frequency scanning angle, and the larger the frequency deviation angle, the larger the scanning sphere top blind spot, and the azimuth beam is fixed and cannot form multiple beams; although the latter has a beam pointing to the normal direction, it has the disadvantage of large loss. Summary of the invention

[0002] In view of the shortcomings of the above-mentioned prior art, the present invention proposes an ultra-low sidelobe dual-polarization active row feed array with variable number of units and unequal power division, which is used in phased array weather radar. It adopts the form of unequal unit active sub-arrays to realize dual-polarization active row feed, and has the characteristics of ultra-low sidelobe, low cost and low loss. The row feed adopts a sub-array-level activation system and is divided into several active sub-arrays (5). Compared with passive arrays, the transmission efficiency and reliability are greatly improved, and compared with unit-level activation, the cost is saved. Each active sub-array (5) has several rows, each row has a multifunctional chip (3), which has several channels, each channel corresponds to a unit array (11), and each unit array (11) is composed of different numbers of dual-polarization antenna units (1). The multifunctional chip (3) has different transceiver links. When transmitting, the input signal of each row is evenly distributed to the multifunctional chip (3) by the total power division network (4). Each channel of the multifunctional chip amplifies the signal and distributes it to antenna units in different unit arrays (11) through a weighted power division network (2). Since the number of units in each unit array (11) is different, but the input power is equal, the energy allocated to the antenna units in the unit arrays (11) with different numbers of units is also different, which forms a first-level amplitude weighting. On this basis, the unit array (11) with a large number of units adopts an unequal power power divider or a series feed network, which can further refine the power distribution between units, realize the second-level amplitude weighting, and finally realize the transmission low sidelobe weighting. The unit array (11) with a small number of units still adopts an equal power power divider, which reduces the design and production costs without affecting the performance. During the reception operation, each unit array (11) is also subjected to an overall amplitude attenuation of different sizes, forming a third-level amplitude weighting, so that the amplitude ratio of the entire line feed array unit is more inclined to Taylor weight distribution or other low sidelobe weight distribution, further realizing the reception ultra-low sidelobe weighting.

[0003] The present invention discloses an ultra-low sidelobe dual-polarization active line-fed array with variable number of units and unequal power division, which specifically comprises N different active sub-arrays (5), each of which comprises a dual-polarization antenna unit (1), a weighted power division network (2), a multifunctional chip (3) and a total power division network (4); the weighted power division network (2) is composed of a plurality of power dividers, each of which is connected to an active channel of the multifunctional chip (3); all the dual-polarization antenna units (1) connected to each power divider form a unit array (11), and the multifunctional chip (3) is connected to the total power division network (4); wherein the dual-polarization antenna unit (1) The signal is sent out through free space, or the electromagnetic wave signal in free space is received. The weighted power division network (2) performs unequal power distribution or synthesis on the signal between the dual-polarized antenna unit (1) and the multifunctional chip (3). The multifunctional chip (3) amplifies, attenuates and phase-shifts the signal. The total power division network (4) then performs equal power distribution or synthesis on the signal between the multifunctional chip (3) and the back-end channel. Each active sub-array (5) has multiple rows, each row corresponds to a multifunctional chip (3), forming multiple channels, and each channel corresponds to a power divider and a unit array (11) of the weighted power division network (2).

[0004] Furthermore, the dual-polarized antenna units (1) are arranged at equal intervals and combined into a unit array (11) comprising different numbers of dual-polarized antenna units (1); the weighted power division network (2) comprises a V-polarized power division network (21) and an H-polarized power division network (22); the V-polarized and H-polarized ports of each unit array (11) are respectively connected to the power divider of the corresponding polarized power division network and are connected to a channel of the multifunctional chip (3); the V-polarized or H-polarized signals are synthesized by the total power division network (4) and finally sent to the back-end channel.

[0005] Furthermore, the row feed array comprises three layers of microwave boards and one layer of motherboard, the multifunctional chip (3) is located on the motherboard, and the V polarization channel and the H polarization channel are arranged in two parallel rows, the V polarization power division network (21) and the dual polarization antenna unit (1) are located above the first layer of microwave boards, a metal floor with a gap is provided between the first layer of microwave boards and the second layer of microwave boards, a microstrip feed line of the H polarization power division network (22) is provided below the second layer of microwave boards, an air cavity is provided between the second layer of microwave boards and the third layer of microwave boards, the signal is transmitted to the third layer of microwave boards through the metal wires between the layers, the feed line in the third layer of microwave boards transmits the signal to the multifunctional chip (3) located below the motherboard, the signal is processed by the multifunctional chip (3) and then goes back to the third layer of microwave boards, is synthesized by the total power division network (4) located on the third layer of microwave boards, and is then sent to the back-end port.

[0006] Furthermore, the weighted power division network (2) is composed of the same number of power dividers as the unit array (11), the power dividers include equal power dividers and unequal power dividers, the number of antenna units is preset to be Ne, when the number of units in the unit array exceeds Ne, the amplitude of each antenna unit satisfies Taylor distribution, when the number of units is less than or equal to Ne, the amplitudes of each antenna unit are equal, that is, when the number of units in the unit array (11) is less than or equal to Ne, equal power dividers are used, and when the number of units in the unit array (11) is greater than Ne, unequal power dividers are used. Each unit array (11) contains an unequal number of antenna units, and the power distribution between the antenna units in the unit array (11) is also unequal, thereby achieving ultra-low side lobes.

[0007] Furthermore, the multifunctional chip (3) comprises a transceiver switch (31), a high power amplifier (32), a low noise amplifier (33), an attenuator (34), and a phase shifter (35); wherein there are two transceiver switches (31), one of which is located at the front-end channel port and connects the transmission link and the reception link, the high power amplifier (32) is located in the transmission link, one end of which is connected to the front-end transceiver switch, and the other end of which is connected to another transceiver switch, the low noise amplifier (33) and the attenuator (34) are located in the reception link, one end of the low noise amplifier (33) is connected to the front-end transceiver switch, and the other end of which is connected to the attenuator (34), the other end of the attenuator (34) is connected to another transceiver switch, and the other transceiver switch is connected to the phase shifter (35); the transceiver switch (31) controls the switching of the transceiver state.

[0008] The beneficial effects of the present invention are

[0009] 1. It can realize dual-polarization working simultaneously, which is an effective solution for high-performance phased array weather radar array subsystem.

[0010] 2. Ultra-low sidelobe characteristics: The line-fed array achieves a transmit sidelobe of -34.2dB and a receive sidelobe of -39.8dB, and the sum of the transmit and receive sidelobes is -73.5dB. The ultra-low sidelobe performance greatly improves the radar's anti-interference and anti-ground clutter capabilities.

[0011] 3. Low-cost feature: The line-fed array adopts sub-array-level activation, which reduces the loss of the transmitting feeder line and the power level of the feeder line. Compared with the unit-level activation, it only uses nearly one-fifth of the active chips, saving a lot of costs.

[0012] 4. Flexible design and wide applicability: The sub-array division and the distribution ratio of the unequal power power divider involved in the present invention can be quickly optimized by setting different goals, which can meet the low sidelobe requirements of line-fed arrays of different sizes. This design method can also provide a reference for other low sidelobe array designs. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The dual-polarization active line-feed array of the present invention is shown in FIG.

[0014] Figure 2 This is a diagram of an active sub-array structure of the dual-polarization active row-fed column structure of the present invention.

[0015] Figure 3 It is a circuit link block diagram of a row of single polarization of the present invention.

[0016] Figure 4 This is a simplified internal structure block diagram of a four-channel multi-function chip.

[0017] Figure 5 An exploded diagram of a row model of the dual-polarization active row-feed column structure of the present invention.

[0018] Figure 6 A top view of a row model of the dual-polarization active row-feed array structure of the present invention.

[0019] Figure 7 The figure is a side view of a row model of the dual-polarization active row-feed array structure of the present invention.

[0020] Figure 8 A bottom view of a row model of the dual-polarization active row feed column structure of the present invention.

[0021] Fig. 9 It is a bar chart of the number of sub-array units in the dual-polarization active row-feed column structure of the present invention.

[0022] Fig.10 The figure shows the unit amplitude distribution of the dual-polarization active row-fed column structure during transmission of the present invention.

[0023] Fig.11 This is the unit amplitude distribution of the dual-polarization active row-fed column structure during reception of the present invention.

[0024] Fig.12 It is the center frequency transmission lobe diagram of the dual-polarization active row-fed column structure of the present invention.

[0025] Fig.13 It is the center frequency receiving lobe diagram of the dual-polarization active row-feed array structure of the present invention.

[0026] Among them, 1 dual-polarized antenna unit, 2 weighted power division network, 3 multi-function chip, 4 total power division network, 5 active sub-array, 21V polarization power division network, 22H polarization power division network, 31 transceiver switch, 32 high power amplifier, 33 low noise amplifier, 34 attenuator, 35 phase shifter. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] like Figure 1 As shown, the active line-fed array is composed of N different active sub-arrays (5), each of which includes several rows of dual-polarized antenna units (1) and a transceiver link. Figure 2 As shown, an active sub-array (5) has several rows, each row has a multifunctional chip (3), each chip has Nc channels, and each channel corresponds to a power divider or a series feed network and a unit array (11) of the weighted power division network (2). Figure 3 As shown, a row circuit of line feed includes a dual-polarized antenna array (1), a weighted power division network (2), a multifunctional chip (3), and a total power division network (4). All dual-polarized antenna units (1) connected to a power divider or a series feed network of the same weighted power division network (2) and an active channel of the multifunctional chip (3) constitute a unit array (11). The present invention achieves ultra-low side lobes by making the number of units contained in each unit array (11) unequal and the power distribution between the units in some unit arrays (11) unequal.

[0029] The dual-polarized antenna unit (1) is the front end of the system. The present invention adopts a microstrip patch antenna, and its feeding method is: H polarization adopts slot coupling feeding, and V polarization adopts microstrip line feeding. Each row of the row feed has Nx antenna units, and the total number of the unit array (11) is Ns=N·Nc. The number of dual-polarized antenna units (1) in each unit array (11) is not equal. The weighted power division network (2) is divided into a V polarization power division network (21) and an H polarization power division network (22), and the amplitude weighting ratio of the antenna units is the same. And each row of the two is composed of Ns equal-power power dividers or unequal-power power dividers or series feeding networks. The branch port of each power divider or series feeding network is connected to the same polarization feeding port of each unit in a unit array (11), and the joint port is connected to a channel of a multifunctional chip (3). A unit array (11) with a unit number less than or equal to 4 uses an equal-power power divider, while a unit array (11) with a unit number greater than 4 uses an unequal-power power divider or a series-feed network.

[0030] For small arrays, the number of units in each unit array (11) can be optimized by traversing all arrangements through exhaustive method. For large arrays, genetic algorithms can be used for optimization, and the optimization goal is to minimize the sidelobe level while satisfying other indicators (such as beam width, etc.). The idea of ​​optimization is to make the amplitude distribution of the entire array as close as possible to the Taylor weight or other low sidelobe weight (Taylor weight of -40dB in this case) distribution of the target sidelobe level. The optimization method is to first preset the power distribution ratio inside the unit array (11) (that is, when the number of units exceeds Ne, the amplitude of each unit satisfies the Taylor distribution, and when the number of units is less than or equal to Ne, the amplitude of each unit is equal, and Ne=4 is taken in this case), and then optimize the number of units in each unit array (11). This design provides an optimal solution obtained by exhaustive optimization, which is Nx=150, Ns=32, dx=0.5226λ0, where λ0 is the free space wavelength corresponding to the center frequency. The number of units in each unit array (11) is as follows Fig. 9 The amplitude distribution of each unit is shown as Fig.10 The array factor pattern of the line feed formed in this way is shown as Fig.12 As shown, its sidelobe level is -34.2dB and the main lobe width is 0.96 degrees.

[0031] The multifunctional chip (3) can amplify, attenuate and phase shift the signal. The simplified block diagram of its internal structure is as follows: Figure 4 As shown, it can be divided into a transceiver switch (31), a high power amplifier (32), a low noise amplifier (33), an attenuator (34), and a phase shifter (35). The high power amplifier (32) is located in the transmitting link, the low noise amplifier (33) and the attenuator (34) are located in the receiving link, the phase shifter (35) is a common part, and the transceiver switch (31) controls the switching of the transceiver state. The multifunctional chip (3) used in this design has Nc=4 channels. Since the number of active sub-arrays (5) is N=8, 8 multifunctional chips (3) are required for each row and each polarization. The RF feeder lines corresponding to the pins of four RF channels of a multifunctional chip (3) are connected to the power dividers or series feed network ports corresponding to the same polarization of four unit arrays (11). When the array is receiving, the attenuator (33) can be used to attenuate the sub-array amplitude as a whole to make the amplitude ratio between units closer to the Taylor distribution, thereby further optimizing the sidelobe level. For the subarrays using unequal power dividers or series-fed networks, after varying degrees of attenuation, the unit amplitude distribution can completely conform to the Taylor distribution, while for the subarrays using equal power dividers, the unit amplitude distribution is step-shaped, but generally conforms to the Taylor distribution. The final amplitude distribution is as follows: Fig.11 As shown, the array factor pattern of the line-fed array is as follows: Fig.13 As shown, its sidelobe level is 39.9dB and the main lobe width is 0.91 degrees.

[0032] Figure 5-8The exploded view, top view, side view and bottom view of a model of a practical design of the dual-polarization active line-feed array of the present invention are shown respectively. The line-feed array model has 3 layers of microwave boards and 1 layer of motherboard. Figure 5 As shown, the multifunctional chip (3) is located on the motherboard, and the multifunctional chip (3) responsible for V polarization and the multifunctional chip (3) responsible for H polarization are arranged in two parallel rows. The V polarization power division network (21) and the dual polarization antenna unit (1) are located above the first layer of microwave board. A metal floor with a gap is provided between the first layer of microwave board and the second layer of microwave board. Below the second layer of microwave board is the microstrip feeder of the H polarization power division network (22). Between the second layer of microwave board and the third layer of microwave board is an air cavity, and the signal is transmitted to the third layer of microwave board through the metal wire between the layers. The feeder in the third layer of microwave board transmits the signal to the multifunctional chip (3) located below the motherboard. After being processed by the multifunctional chip (3), the signal is returned to the third layer of microwave board, synthesized by the total power division network (4) of the corresponding polarization located on the third layer of microwave board, and connected to the back-end port.

[0033] The present invention is not limited to the above specific implementations, and the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made to the above implementations based on the technical essence of the present invention shall be included in the protection scope of the present invention.

Claims

1. An ultra-low sidelobe dual-polarization active line-fed array with variable number of elements and unequal power division, characterized in that: The invention comprises N different active sub-arrays (5), each of which comprises a dual-polarized antenna unit (1), a weighted power division network (2), a multifunctional chip (3) and a total power division network (4); the weighted power division network (2) is composed of a plurality of power dividers, each of which is connected to an active channel of the multifunctional chip (3); all the dual-polarized antenna units (1) connected to each power divider form a unit array (11), and the multifunctional chip (3) is connected to the total power division network (4); wherein the dual-polarized antenna unit (1) sends a signal through free space, or The electromagnetic wave signal in the free space is received, the weighted power division network (2) performs unequal power distribution or synthesis on the signal between the dual-polarized antenna unit (1) and the multifunctional chip (3), the multifunctional chip (3) performs amplification, attenuation and phase shift on the signal, and the total power division network (4) performs equal power distribution or synthesis on the signal between the multifunctional chip (3) and the back-end channel; each active sub-array (5) has a plurality of rows, each row corresponds to a multifunctional chip (3), forming a plurality of channels, each channel corresponds to a power divider and a unit array (11) of the weighted power division network (2).

2. The ultra-low sidelobe dual-polarization active line-fed array with variable number of elements and unequal power division according to claim 1, characterized in that: The dual-polarized antenna units (1) are arranged at equal intervals and combined into a unit array (11) comprising different numbers of dual-polarized antenna units (1); the weighted power division network (2) comprises a V-polarized power division network (21) and an H-polarized power division network (22); the V-polarized and H-polarized ports of each unit array (11) are respectively connected to the power divider of the corresponding polarized power division network and are connected to a channel of the multifunctional chip (3); the V-polarized or H-polarized signals are synthesized by the total power division network (4) and finally sent to the back-end channel.

3. The ultra-low sidelobe dual-polarization active line-fed array with variable number of elements and unequal power division according to claim 1, characterized in that: The row feed array comprises three layers of microwave boards and one layer of motherboard. The multifunctional chip (3) is located on the motherboard so that the V polarization channels and the H polarization channels are arranged in two parallel rows. The V polarization power division network (21) and the dual polarization antenna unit (1) are located above the first layer of microwave boards. A metal floor with a gap is provided between the first layer of microwave boards and the second layer of microwave boards. A microstrip feed line of the H polarization power division network (22) is provided below the second layer of microwave boards. An air cavity is provided between the second layer of microwave boards and the third layer of microwave boards. The signal is transmitted to the third layer of microwave boards through the metal wires between the layers. The feed line in the third layer of microwave boards transmits the signal to the multifunctional chip (3) located below the motherboard. The signal is processed by the multifunctional chip (3) and then goes back to the third layer of microwave boards. The signal is synthesized by the total power division network (4) located on the third layer of microwave boards and then sent to the back-end port.

4. The ultra-low sidelobe dual-polarization active line-fed array with variable number of elements and unequal power division according to claim 1, characterized in that: The weighted power division network (2) is composed of the same number of power dividers as the unit array (11), the power dividers including equal power dividers and unequal power dividers, the number of antenna units is preset to be Ne, when the number of units in the unit array exceeds Ne, the amplitude of each antenna unit satisfies Taylor distribution, when the number of units is less than or equal to Ne, the amplitudes of each antenna unit are equal, that is, when the number of units in the unit array (11) is less than or equal to Ne, equal power dividers are used, and when the number of units in the unit array (11) is greater than Ne, unequal power dividers are used.

5. The ultra-low sidelobe dual-polarization active line-fed array based on unequal unit subarrays according to claim 4, characterized in that: The number of antenna units contained in each unit array (11) is different, and the power distribution between the antenna units inside the unit array (11) is also different, so as to achieve ultra-low side lobes.

6. The ultra-low sidelobe dual-polarization active line-fed array based on unequal unit subarrays according to claim 1, characterized in that: The multifunctional chip (3) comprises a transceiver switch (31), a high power amplifier (32), a low noise amplifier (33), an attenuator (34), and a phase shifter (35); wherein there are two transceiver switches (31), one of which is located at a front-end channel port and is connected to a transmission link and a reception link, the high power amplifier (32) is located in the transmission link, one end of which is connected to the front-end transceiver switch, and the other end of which is connected to another transceiver switch, the low noise amplifier (33) and the attenuator (34) are located in the reception link, one end of the low noise amplifier (33) is connected to the front-end transceiver switch, and the other end of which is connected to the attenuator (34), the other end of the attenuator (34) is connected to another transceiver switch, and the other transceiver switch is connected to the phase shifter (35); the transceiver switch (31) controls the switching of the transceiver state.

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