Broadband high-efficiency 1bit circularly polarized reconfigurable transmission unit and array antenna

Abstract

The invention discloses a broadband high-efficiency 1bit circularly polarized reconfigurable transmission unit and an array antenna. The reconfigurable transmission unit comprises a circularly polarized wave receiving patch, an upper-layer dielectric substrate, an upper-layer metal ground plane, a middle dielectric substrate, a DC bias line, a lower-layer metal ground plane, a lower-layer dielectric substrate and a radiation patch which are sequentially arranged from top to bottom, and can directly realize two unit phases of 0 degree and 180 degrees of circularly polarized transmission waves; the equivalent rotation phase is free of dispersion; the state of each unit in the transmission array is controlled through the FPGA, + / -60-degree large-angle scanning of circular polarization transmission beams can be achieved, the beam performance is good, and high circular polarization purity is achieved. The array antenna provided by the invention has the advantages of wide axial ratio bandwidth and high aperture efficiency, and has relatively high application potential and value in scenes requiring real-time electric control circular polarization beam scanning antennas, such as application of long-distance radar detection, communication systems and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of microwaves and antennas, and in particular to a broadband high-efficiency 1-bit circularly polarized reconfigurable transmission unit and an array antenna. Background Art

[0002] As an important component of long-range radar detection and wireless communication systems, circularly polarized antennas have received extensive research attention due to their advantages in resisting path loss, Faraday rotation and multipath effects. However, with the development of technology, the requirements for real-time high-performance circularly polarized beam scanning make it difficult for traditional mechanical scanning and electronic scanning antennas with additional phase shifter networks to meet practical application needs. Due to some inherent defects, such as bulky mechanical structure and expensive phase shifter network costs, traditional scanning methods have gradually withdrawn from the researchers' field of vision under the trend of modern low-cost, lightweight and easy-to-integrate devices.

[0003] Existing metasurface designs can achieve flexible control of the amplitude, phase and polarization of electromagnetic waves by integrating diodes or MEMS microelectromechanical systems, thereby realizing low-cost, low-profile and easy-to-integrate antenna equipment, which basically meets the needs of existing radar communication systems; however, due to the complexity of circularly polarized antenna design, most of the existing reconfigurable metasurfaces are limited to the phase control of simple linearly polarized waves. Such antenna equipment is susceptible to spatial path fading, and due to the existence of multipath effects, the detection and communication quality of such equipment is reduced.

[0004] The emergence of reconfigurable circularly polarized array antennas can effectively solve the above problems and has significant advantages in application fields such as radar anti-interference; however, the existing circularly polarized array antennas are mostly limited to the category of reflective array antennas, which usually require a feed antenna with a higher profile on the same side of the beam scattering direction, and there are significant feed shielding and high profile problems. Therefore, the rarely reported circularly polarized reconfigurable transmission arrays have gradually appeared in the field of vision of researchers. However, on the one hand, the existing circularly polarized transmission arrays have great difficulties in the design of reconfigurable metasurface units, and on the other hand, the complex multi-device integration and structure make them difficult to apply to practical applications. In addition, both reconfigurable circularly polarized reflective arrays and transmission arrays are restricted by limited bandwidth and aperture efficiency. In order to improve the bandwidth and efficiency performance of circularly polarized antennas, more complex multi-bit structures are often required, but this brings about the problem of multi-layer complex structures and integration of more devices. And with the development of measurement and control technology, lightweight and easy-to-integrate antenna systems also need to have large-angle beam scanning capabilities, which is more difficult for circularly polarized antennas. Therefore, in various practical application scenarios, there are still many problems to be solved in the reconfigurable circularly polarized array antenna. Summary of the invention

[0005] The purpose of the present invention is to propose a broadband, high-efficiency 1-bit circularly polarized reconfigurable transmission unit and array antenna, which only rely on a single functional layer to achieve phase control of circularly polarized waves, thereby solving the problem of complex structure of existing circularly polarized transmission units; in addition, the combination of a broadband planar circularly polarized feeding array, a broadband and efficient circularly polarized unit and a specific unit arrangement scheme in the array enables the 1-bit circularly polarized reconfigurable transmission array antenna to have broadband, high efficiency and good polarization purity large-angle beam scanning capability, greatly reducing the design complexity and device requirements of the circularly polarized array antenna, and realizing a circularly polarized reconfigurable transmission array antenna with simple structure, low manufacturing cost, compactness and easy integration.

[0006] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0007] In a first aspect, the present invention discloses a broadband high-efficiency 1-bit circularly polarized reconfigurable transmission unit, which comprises a circularly polarized wave receiving patch, an upper dielectric substrate, an upper metal ground plane, a DC+ DC bias network, an intermediate dielectric substrate, a DC- DC bias network, a lower metal ground plane, a lower dielectric substrate and a radiation patch arranged in sequence from top to bottom;

[0008] A C-shaped annular gap is arranged in the center of the circularly polarized wave receiving patch, and two rotationally symmetrical rectangular grooves are etched on the outer ring of the circularly polarized wave receiving patch to receive and reflect the specified circularly polarized wave;

[0009] The outer circle of the radiation patch is etched with two rotationally symmetrical rectangular grooves, the rectangular grooves of the radiation patch and the rectangular grooves of the receiving patch are in different directions, and a circular ring gap is etched inside to form an inner disc and an outer radiator; the radiation patch bridges the inner disc and the outer radiator by integrating two PIN diodes in the same direction, and only one of the two PIN diodes is selected at a time to selectively connect the inner disc and the outer radiator;

[0010] The upper metal ground plane and the lower metal ground plane are both pre-punched for transmission of RF radio frequency and DC direct current signals;

[0011] The DC+ bias network and the DC- bias network are attached to both sides of the intermediate dielectric substrate respectively; one end of the DC+ bias network is connected to the radiator outside the radiation patch through a metallized via and an RF choke inductor, and the other end is connected to the FPGA control board through a socket; and the DC- bias network is mainly composed of a fan-shaped open-circuit branch and a bent metal microstrip line connected in series, one end of which is connected to the RF metallized through-hole, and the other end is connected to the metal ground plane through a metallized via; the DC+ bias network and the DC- bias network are respectively connected to the positive and negative ends of the PIN diode to form a complete DC signal path;

[0012] The receiving patch and the radiating patch are connected through a central metallized through-hole. The spatial electromagnetic wave is received by the receiving patch and converted into a current signal, which is then transmitted to the radiating patch through the metallized through-hole and then transmitted to the outer radiator through the turned-on PIN diode. The current signal is converted into a spatial electromagnetic wave again, completing the process of receiving, converting, conducting and re-radiating the RF radio frequency energy signal. By changing the DC bias voltage to control the on-off state of the two PIN diodes, the 180° phase control of the same circularly polarized radiated electromagnetic wave of the metasurface unit is performed.

[0013] Furthermore, the metal patches on both sides of the PIN diode are provided with extension parts.

[0014] Furthermore, the upper dielectric substrate, the middle dielectric substrate and the lower dielectric substrate are all squares with a side length of 10 mm, and their electrical dimensions do not exceed one half of the working wavelength;

[0015] The outer circular rings of the receiving patch and the radiating patch are of the same size so that the resonant frequencies of the two are consistent; the inner metal circular plate is optimized differently according to the reception, reflection and radiation characteristics of the circularly polarized wave; the slot center of the outer ring and the connection center of the metal microstrip line maintain a slot angle of 45°, 135°, -45° or -135°; the polarization properties of the patch unit are changed by adjusting the slot angle.

[0016] Furthermore, the DC+ bias network adopts a 0.2 mm thin metal microstrip line extending in the +x-axis direction; the DC- bias network is composed of a fan-shaped open-circuit branch and a bent metal microstrip line connected in series, one end of which is connected to the RF radio frequency metallized through hole, and the other end is connected to the metal ground plane through the metallized via hole; the metallized via hole is located at a certain distance from the receiving and radiating patches;

[0017] The fan-shaped open-circuit branch is placed at a distance of one quarter wavelength from the RF radio frequency through hole, and the radius of the fan-shaped open-circuit branch is one quarter wavelength of the operating frequency.

[0018] Furthermore, the RF choke inductor connected to the DC+ DC bias network can be replaced by a narrow and curved metal microstrip line.

[0019] Furthermore, the DC+ DC bias network of each unit between the upper metal ground plane and the lower metal ground plane is guided to both sides of the transmission array and uniformly connected to the FPGA control board through a socket.

[0020] In a second aspect, the present invention discloses a reconfigurable transmission array antenna using a 1-bit metasurface unit, wherein the reconfigurable transmission array antenna comprises a circularly polarized planar feed array, a circularly polarized transmission surface, and an FPGA control board;

[0021] The circularly polarized planar feeding array is used to radiate the circularly polarized electromagnetic waves required by the transmission surface;

[0022] The circularly polarized transmission surface comprises a plurality of 1-bit circularly polarized reconfigurable transmission units as described in claims 1 to 6, wherein the 1-bit circularly polarized reconfigurable transmission units are arranged in an n×n array, and adjacent 4×4 1-bit circularly polarized reconfigurable transmission units constitute a supercell, wherein the supercell is formed by rotating and replicating a 2×2 structural block, wherein the 2×2 structural blocks are arranged in an orthogonal rotation manner, and the two 1-bit circularly polarized reconfigurable transmission units before and after rotation constitute two orthogonal units according to the placement orientation of the diode, and the 1-bit phase before the unit rotation is 0° and 180°; and the 1-bit phase after the unit rotation is 270° and 90°;

[0023] The FPGA control board allocates different bias voltages to each 1-bit circularly polarized reconfigurable transmission unit in the circularly polarized transmission plane, and performs phase-independent control on n×n 1-bit circularly polarized reconfigurable transmission units, so that the reconfigurable transmission array antenna performs ±60° large-angle beam scanning in a two-dimensional half space.

[0024] Furthermore, the circularly polarized planar feed array antenna is composed of 2×2 corner-cut square patches, and the energy is evenly distributed to four corner-cut square patches arranged in a rotational manner in the order of 0°, 90°, 180° and 270° through a ring series feed network to form a broadband planar feed array antenna with a three-dimensional symmetrical circularly polarized radiation beam shape;

[0025] The bottom of the circularly polarized planar feed array antenna is a complete metal ground plane, and the top layer is covered with a super-surface impedance matching layer composed of a plurality of small metal square pieces to achieve wide-angle impedance matching.

[0026] Furthermore, the FPGA control board is connected to the DC+ DC bias network concentrated on both sides of the transmission array antenna through a total of 16 sockets on both sides; one socket on the left side controls two rows of n / 2 1-bit metasurface units on the left side of the corresponding row, and one socket on the right side controls two rows of n / 2 1-bit metasurface units on the right side of the corresponding row; the calculated beam phase coding is pre-stored in the FPGA control board.

[0027] Furthermore, n is equal to 16, the circularly polarized planar feed array radiates right-hand circularly polarized electromagnetic waves, the distance between the feed source phase center and the transmission array is set to 100 mm, and the focal diameter ratio is 0.625, so as to irradiate each receiving patch of the transmission array; the transmission array mirror-reflects left-hand circularly polarized electromagnetic waves and efficiently receives right-hand circularly polarized electromagnetic waves, and controls the phase of the electromagnetic waves re-radiated by each metasurface unit through the FPGA control board, so as to perform reconfigurable and efficient directional radiation of the transmitted right-hand circularly polarized waves.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] First, the broadband, high-efficiency, 1-bit circularly polarized reconfigurable transmission unit and array antenna of the present invention realize the broadband and high-efficiency 1-bit circularly polarized electromagnetic wave phase control function with the minimum 2 PIN diodes and a single-layer phase control functional layer required by the transmission unit, which greatly simplifies the structure and design complexity of the circularly polarized reconfigurable transmission array.

[0030] Second, the broadband high-efficiency 1-bit circularly polarized reconfigurable transmission unit and array antenna of the present invention, the unit in the reconfigurable transmission array is composed of 4×4 orthogonal rotation supercells, this arrangement can eliminate the main polarization sidelobe caused by the 1-bit phase quantization error, and can also eliminate the stray sidelobe formed by the cross-polarization component in the mirror image, so that the main polarization component is effectively converged in the main beam direction to improve the beam gain and aperture efficiency, and can also significantly broaden the axial ratio bandwidth of the circularly polarized beam;

[0031] Thirdly, the broadband high-efficiency 1-bit circularly polarized reconfigurable transmission unit and array antenna of the present invention can realize broadband symmetrical 3D radiation beam illumination by adopting a circularly polarized planar array antenna as the feed source of the reconfigurable circularly polarized transmission array antenna, and also facilitate lightweight and low-profile integration of the antenna system, making the radar or communication system more compact;

[0032] Fourthly, the broadband, high-efficiency, 1-bit circularly polarized reconfigurable transmission unit and array antenna of the present invention can realize rapid switching of array unit states by adopting a high-speed FPGA control board, thereby changing the phase distribution on the aperture plane and realizing ±60° large-angle beam scanning in a two-dimensional half space, which is very suitable for communication and detection systems with fast and instant scanning beams. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the structure of a broadband, high-efficiency, 1-bit circularly polarized reconfigurable transmission unit proposed by the present invention;

[0034] Figure 2 for Figure 1 The top view of the 1-bit circularly polarized reconfigurable transmission unit shown is specifically a receiving patch structure;

[0035] Figure 3 for Figure 1 The bottom view of the 1-bit circularly polarized reconfigurable transmission unit shown is specifically a radiation patch structure including two integrated PIN diodes and an RF choke inductor;

[0036] Figure 4 Schematic diagram of the DC+ and DC- bias network of the 1-bit circularly polarized reconfigurable transmission unit;

[0037] Figure 5 It is a schematic diagram of the metal ground plane structure;

[0038] Figure 6 The amplitude response curves of the co-polarization and cross-polarization components of the reflection and transmission of the 1-bit circularly polarized reconfigurable transmission unit when the left-handed circularly polarized electromagnetic wave is irradiated to the unit receiving patch in the normal direction;

[0039] Figure 7 The amplitude response curves of the co-polarization and cross-polarization components of the reflection and transmission of the 1-bit circularly polarized reconfigurable transmission unit when the right-handed circularly polarized electromagnetic wave is irradiated to the unit receiving patch in the normal direction;

[0040] Figure 8 Schematic diagram of the amplitude response curves of the co-polarization and cross-polarization transmission components of the 1-bit circularly polarized reconfigurable transmission unit working in two states (Figure (a)), and a schematic diagram of the phase response curves of the co-polarization transmission components in two states (Figure (b));

[0041] Fig. 9 The three-dimensional schematic diagram (Figure (a)) and side view (Figure (b)) of the optimized circularly polarized planar feed array antenna;

[0042] Fig.10 Schematic diagram of the main radiator of the circularly polarized planar fed array antenna (Figure (a)) and the schematic diagram of the metasurface wide-angle impedance matching layer (Figure (b));

[0043] Fig.11 is the reflection coefficient S of the circularly polarized planar feed array antenna 11 curve (Figure (a)), and the curve of gain and axial ratio in the main beam direction changing with frequency (Figure (b));

[0044] Fig.12 Schematic diagram of two unit structures corresponding to orthogonally placed radiation patches, Figure (a) is a vertical unit, and Figure (b) is a horizontal unit;

[0045] Fig.13 The schematic diagram of a 4×4 supercell constructed by orthogonally rotating two units (Figure (a)), and the corresponding actual diagram (Figure (b));

[0046] Fig.14 The schematic diagram of the 16×16 unit arrangement of the 1-bit circularly polarized reconfigurable transmission array antenna implemented by the present invention;

[0047] Fig.15 The schematic diagram is a working principle diagram of a 1-bit circularly polarized reconfigurable transmission array antenna system, which includes a planar feed antenna and a transmission array.

[0048] Fig.16 The bottom view of the 1-bit circularly polarized reconfigurable transmission array includes a schematic diagram of the receiving patch distribution and the socket interfaces on both sides for connecting to the FPGA.

[0049] Fig.17 It is the aperture-plane phase distribution diagram of the fixed-angle transmission beam of the 1-bit circularly polarized reconfigurable transmission array antenna system;

[0050] Fig.18 It is the far-field normalized radiation pattern of the fixed beam of the 1-bit circularly polarized reconfigurable transmission array antenna system;

[0051] Fig.19 The gain of the fixed beam of the 1-bit circularly polarized reconfigurable transmission array antenna system and the corresponding aperture efficiency are plotted against frequency;

[0052] Fig. 20 The axial ratio bandwidth curve of the fixed beam main beam radiation direction of the 1-bit circularly polarized reconfigurable transmission array antenna system;

[0053] Fig.21 The far-field radiation pattern of ±60° beam scanning realized by the 1-bit circularly polarized reconfigurable transmission array antenna system under FPGA control in the diagonal plane (D plane, azimuth angle phi = 45°) (Figure (a)), as well as the schematic diagram of the gain and axial ratio envelope in the main beam direction (Figure (b));

[0054] Fig. 22 The far-field radiation pattern of ±60° beam scanning realized by the 1-bit circularly polarized reconfigurable transmission array antenna system under FPGA control in the horizontal plane (E plane, azimuth angle phi = 0°) (Figure (a)), as well as the gain and axial ratio envelope diagram in the main beam direction (Figure (b));

[0055] Fig.23 The far-field radiation pattern of ±60° beam scanning realized by the 1-bit circularly polarized reconfigurable transmission array antenna system under FPGA control in the vertical plane (H plane, azimuth angle phi = 90°) (Figure (a)), as well as the schematic diagram of the gain and axial ratio envelope in the main beam direction (Figure (b));

[0056] The accompanying drawings are marked as follows:

[0057] 1. Right-hand circularly polarized receiving patch; 2. Right-hand circularly polarized radiating patch; 3. PIN diode; 4. RF choke inductor; 5. Central RF signal conduction metallized through hole; 6. Upper dielectric substrate; 7. Middle dielectric substrate; 8. Lower dielectric substrate; 9. Upper metal ground plane; 10. Lower metal ground plane; 11. DC-direct current bias network composed of fan-shaped branches and bent microstrip lines; 12. DC-metallized vias; 13. DC+direct current bias network and metallized vias; 14. Dielectric substrate pp bonding layer; 15. Dielectric substrate pp bonding layer; 16. Circularly polarized planar fed array antenna main radiator patch; 17. Planar fed array antenna annular series feeding network; 18. Metasurface wide-angle impedance matching layer; 19. Planar fed array antenna metal ground plane; 20. Feed antenna lower dielectric substrate; 21. Feed antenna upper dielectric substrate; 22. Feed antenna central SMA micro connector feeding diagram. DETAILED DESCRIPTION

[0058] The embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0059] like Figure 1 As shown, the present invention discloses a broadband high-efficiency 1-bit circularly polarized reconfigurable transmission unit, which comprises, from top to bottom, a right-handed circularly polarized receiving patch 1 arranged on the top layer, an upper dielectric substrate 6, an upper metal ground plane 9, a DC+ DC bias network and a metallized via 13, an intermediate dielectric substrate 7, a DC-DC bias network 11 composed of fan-shaped branches and bent microstrip lines, a lower metal ground plane 10, a lower dielectric substrate 8, and a right-handed circularly polarized radiation patch 2 integrating a radio frequency choke inductor 4 and a PIN diode 3; the three-level dielectric substrates are bonded by PP bonding layers 14 and 15; the central metallized via 5 penetrates all dielectrics and two layers of metal ground planes to connect the right-handed circularly polarized receiving patch 1 and the right-handed circularly polarized radiation patch 2 for conducting radio frequency signals.

[0060] All dielectric substrates and metal ground planes are preferably squares with a side length of 10 mm within the X-band range, which is one-third of the wavelength of the central operating frequency, and preferably the size does not exceed one-half of the operating wavelength.

[0061] The material of the upper and lower dielectric substrates is preferably F4B material with a dielectric constant of 3.5 and a loss tangent of 0.0015, and the thickness is preferably 1.524 mm. The use of dielectric substrates with different dielectric constants and different heights has a greater impact on the performance of the receiving and radiating patches on the top and bottom layers. While ensuring the effective reception and transmission of circularly polarized electromagnetic waves by metal patches under a specific unit size, the selection of the more common and relatively inexpensive preferred F4B material is beneficial to reducing the cost of the entire transmission array antenna.

[0062] The specific structure of the top right-hand circular polarization receiving patch 1 is as follows Figure 2 As shown, a C-shaped annular seam is dug out in the center, and two rectangular grooves are dug at the diagonal corners of the outer ring structure. The metal microstrip line located on the left side in the horizontal direction bridges the outer ring structure and the central disc; the positional relationship between the metal microstrip line and the rectangular groove determines the polarity of the received electromagnetic wave. In order to achieve the reception of right-handed circularly polarized waves, an angle of 45° is formed here. It should be noted that the effect of placing this bridging metal microstrip line on the right side horizontally is equivalent; in addition, the metal microstrip line is placed vertically, which can change the polarity of the received electromagnetic wave and selectively receive left-handed circularly polarized waves. The figure is only an example and does not limit the function of the receiving patch.

[0063] Figure 3The structure shown is a top-level right-handed circularly polarized radiation patch 2. Two rotationally symmetrical rectangular grooves are also etched on the outer circle, which are inconsistent with the orientation of the receiving patch. A circular gap is etched inside, and two PIN diodes are integrated to achieve bridging of the internal and external patches. To facilitate welding, the metal patches on the left and right sides of the PIN diode are partially extended. The inner circular patch of the radiation patch 2 is physically isolated from the outer ring radiation patch, where the two rectangular grooves of the outer ring patch are similar to the mechanism of the receiving patch; the radiation of different phases of the same polarized wave is achieved by selective connection of the two integrated PIN diodes 3; similarly, placing the PIN diode vertically can change the polarization characteristics of the radiated electromagnetic wave; the voltage that controls the on-off state of the PIN diode is applied to the outer ring radiation patch through the RF choke inductor 4, and ensures the isolation of the RF radio frequency signal from the DC bias network. Only one of the two PIN diodes with the same orientation integrated in the radiation patch is turned on at a time. By changing the DC bias voltage to control the on-off state of the two PIN diodes, the 180° phase regulation of the same circularly polarized electromagnetic wave radiated by the metasurface unit can be achieved; wherein, the phase of the two diodes is 0° in state I (ON / OFF) and 180° in state II (OFF / ON); the two states are controlled by applying different voltages only through a single DC+ DC bias line; the two states can be equivalent to physical rotations achieved by electrical control, so it has dispersion-free broadband phase regulation characteristics. The outer rings of the receiving patch and the radiation patch are of the same size to ensure that the resonant frequencies of the two are consistent; the inner metal disc can be optimized differently according to the reception, reflection and radiation characteristics of the circularly polarized wave. The center of the outer ring slot is kept at an angle of 45° or 135° with the center of the metal microstrip line connection, which can achieve a more ideal circular polarization characteristic; if the polarization properties of the patch unit are to be changed, the slot angle can be selected at an angle of -45° or -135°.

[0064] Figure 4 The structure shown is a DC-DC bias network 11. The attached intermediate dielectric substrate 7 benefits from the isolation of the metal ground planes 9 and 10 on both sides. Theoretically, any material of any thickness can be selected. Here, in order to ensure the continuity of impedance, the same material F4B material is still selected, with a height of 0.508mm. The DC-DC bias network 11 is composed of a fan-shaped open-circuit branch and a curved metal microstrip line in series, which can be equivalent to a low-pass filter. The two ends are respectively connected to the RF radio frequency conduction signal via and the metal ground plane to prevent the leakage of RF radio frequency signals.

[0065] Figure 5 The detailed structure of the two-layer metal ground planes 9 and 10 is shown in FIG. The central white hole allows the RF signal to pass through, and the lower white hole allows the voltage signal of the DC+ bias network to pass through. Figure 5The red dots at the same position are metallized vias that connect metal patches with different functions. Both layers of metal ground planes are pre-punched for the transmission of RF and DC+ bias network signals.

[0066] The two PIN diodes in the radiating patch are oriented in the same direction. The positive electrode of the PIN diode on the left is connected to the external patch, and the negative electrode is connected to the internal patch; the positive electrode of the PIN diode on the right is connected to the internal patch, and the negative electrode is connected to the external patch; the external patch is connected to the DC+ bias network through an RF choke inductor. Placing the two-layer DC bias network in the middle of the two-layer metal ground plane can effectively eliminate its influence on the receiving or radiating patch; if you want to simplify the structure, you can also use a single-layer metal ground plane to isolate the receiving and radiating patches; a thin and curved microstrip line and a fan-shaped open branch connected to the DC-bias network constitute an equivalent low-pass filter, which effectively prevents the leakage of RF signals and allows DC signals to pass; the RF choke inductor connected to the DC+ bias network can be replaced by a thin and curved microstrip line. In this embodiment, the DC-bias network uses a 0.2mm thin metal microstrip line, extending in the +x axis direction and connected to the fan-shaped branch; the fan-shaped branch is placed at a quarter wavelength away from the RF through hole, and the opening angle of the fan-shaped branch is The larger the opening angle, the wider the bandwidth for preventing RF radio frequency current signal leakage. The radius of the fan-shaped branch is one quarter wavelength of the operating frequency. To make the structure compact, the thin and bent metal wire is placed along the -y axis. The width and gap of the bent wire are both 0.2mm, and it is connected to the metal ground plane through a metallized via. The location of the metallized via must ensure a certain distance from the receiving and radiating patches. The radiating patch is connected to the DC+ DC bias network located in the middle of the ground plane through an RF choke inductor and a metallized via. The choke inductor can be replaced by a thin and bent metal wire. In order to independently distribute different DC voltages to each unit, the DC+ DC bias network of each unit between the two ground planes is guided to both sides of the transmission array and uniformly connected to the FPGA control board through a socket.

[0067] As a functional description of the working mechanism of the above unit, Figure 6 and Figure 7The scattering and transmission amplitude response curves of the metasurface unit structure are respectively shown when left-hand circular polar wave and right-hand circular polar wave are vertically irradiated onto the receiving patch on the top layer of the unit; when left-hand circular polar wave is incident, the unit achieves efficient rLL co-polarization reflection, and the reflection loss is less than 1dB in the broadband range of 9.5-10.5GHz, and almost no energy is converted into cross-polarization component for reflection or transmitted to the other side; when right-hand circular polar wave is incident, the unit achieves efficient tRR co-polarization transmission, and the insertion loss is less than 1.5dB in the broadband range of 9.7-10.5GHz, and almost no energy is reflected or converted into cross-polarization component for transmission, and the cross-polarization transmission component is less than -15dB in the range of 9.8-10.4GHz; as a general description, the above performances are obtained when the unit works in state I (i.e., PIN#1 / PIN#2 is in ON / OFF state), and the same performance can be obtained when the unit works in state II (i.e., PIN#1 / PIN#2 is in OFF / ON state).

[0068] Since the metasurface unit has 1-bit phase control function, Figure 8 The co-polarization and cross-polarization transmission amplitude responses of the metasurface unit working in two different states (state I and state II) and the corresponding co-polarization transmission component phase response curves are shown when the unit is subjected to right-hand circular polarization incidence. It can be seen that the transmission amplitude responses in the two states are basically consistent, but the phase difference is maintained at around 180° in the entire 8-12 GHz X-band. In fact, the two working states of the unit are equivalent to a physical rotation of 180°. This type of equivalent rotation phase achieved by electrical control is dispersion-free. Theoretically, the phase difference between the two is 180° at any frequency, which ensures the broadband phase modulation capability of the 1-bit metasurface unit described in the present invention.

[0069] The present invention also proposes a reconfigurable transmission array antenna using 1-bit metasurface units, comprising a circularly polarized planar feed array and a circularly polarized receiving and reradiating transmission surface; the circularly polarized planar feed array radiates the circularly polarized electromagnetic waves required by the transmission surface; the aforementioned 1-bit metasurface units are arranged in an n×n array with a specific 4×4 structural block to construct the transmission surface; and different bias voltages are assigned to each 1-bit unit in the transmission surface through the FPGA control board, so that the phase of the n×n unit can be independently controlled, so that the reconfigurable transmission array antenna can achieve efficient ±60° large-angle beam scanning in a two-dimensional half space. The circularly polarized planar feed array antenna is composed of 2×2 classic corner-cut square patches, and the energy is evenly distributed to four corner-cut square patches arranged in a sequential rotation manner through a ring series feed network, thereby forming a broadband planar feed array antenna with a three-dimensional symmetrical circularly polarized radiation beam shape; the bottom of the feed array antenna is a complete metal ground plane, and the top layer is covered with a metasurface impedance matching layer composed of a number of small metal square pieces to achieve wide-angle impedance matching.

[0070] Specifically, in order to realize a broadband and high-efficiency circularly polarized reconfigurable transmission array antenna, in addition to the broadband and high-efficiency unit performance, the performance of the feed antenna also has an important influence on the performance of the overall reconfigurable transmission array antenna; the feed antenna adopts an optimized setting, and its main radiation patch 16 and the annular series feed network 17 constitute a small 2×2 circularly polarized planar array antenna. The annular series feed network 17 ensures that the energy fed into the central single-ended SMA connector 22 is evenly distributed to four rectangular cut-corner patches placed in a rotational manner in the order of 0°, 90°, 180° and 270°, so as to realize the effective superposition of the desired circularly polarized waves. In order to meet the unit performance, the 2×2 planar array antenna here radiates right-handed circularly polarized waves; the super-surface wide-angle impedance matching layer 18 attached to the top of the upper dielectric 21 plays a role in further widening the working bandwidth; the bottom metal ground plane 19 and the main radiation patch 16 are printed on both sides of the lower dielectric substrate 20; the inner core probe of the central single-ended SMA connector 22 passes through the metal ground plane and is connected to the center of the annular series feed network 17; Fig. 9 The 3D exploded view and side view of the 2×2 circularly polarized planar feed array antenna are shown; the main radiator patch and the metasurface wide-angle impedance matching layer are shown in Fig.10 middle.

[0071] The transmission surface adopts a 4×4 structural sub-block with a specific pattern arrangement, which can effectively eliminate the co-polarization sidelobe problem caused by 1-bit quantization error, and can further eliminate the stray sidelobe formed by the cross-polarization component in the mirror image, so that the energy is concentrated in the main beam direction, thereby greatly increasing the radiation gain and aperture efficiency of the transmission array antenna;

[0072] The FPGA control board is connected to the DC+ DC bias network concentrated on both sides of the transmission array antenna through a socket; among them, a socket on the left side controls two rows of n / 2 1-bit metasurface units on the left side of the corresponding row, and a socket on the right side controls two rows of n / 2 1-bit metasurface units on the right side of the corresponding row; by pre-storing the calculated beam phase encoding into the FPGA, flexible and controllable beam scanning changes can be achieved.

[0073] As an example of preferred parameters for a circularly polarized planar feed array antenna, Fig.11 The reflection coefficient S of the fed antenna is given by 11 The gain and axial ratio characteristic curves of right-hand circularly polarized waves are shown in Figure 2. It can be seen that the measured reflection coefficient is kept below -10dB in the wide frequency range of 8-12GHz, indicating that the energy is basically fed into the feed antenna through the SMA connector to generate effective radiation. The gain in the main beam direction is as high as 12dBi in the wide frequency range of 8.5-10.5GHz, and the axial ratio curve is below 3dB in the range of 8.8-12GHz, indicating that the radiation beam has good polarization purity. It should be noted that by mirroring the main radiator patch layer, a left-hand circularly polarized wave radiating antenna with similar performance can be easily obtained.

[0074] As a further optimization of the reconfigurable array antenna, the radiation patch layer of the unit in the array is divided into two types: Fig.12 The PIN diodes shown are vertical units placed vertically and horizontal units placed horizontally, represented by the letters 'V' and 'H' in the lower right corners respectively; the two units are divided into Fig.13 The orthogonal rotation pattern shown is placed to form a 4×4 structural block supercell; the 1-bit circularly polarized reconfigurable transmission array antenna example is a collection of 16×16 units composed of 4×4 such structural block supercells. The structural style of each unit in the array is shown in the figure below. Fig.14 shown.

[0075] Fig.15 The overall structure diagram of the 1-bit circularly polarized reconfigurable transmission array antenna system as an example of the present invention is shown, which consists of a right-handed circularly polarized planar feed array antenna placed at the bottom and a reconfigurable transmission plane placed at the top, and of course also includes an FPGA control board for controlling the state of the radiation patch.

[0076] The working mechanism of the antenna system can be briefly described as follows: the right-hand circularly polarized planar fed array antenna radiates a three-dimensionally symmetrical right-hand circularly polarized wide beam, which is irradiated to the receiving layer of the reconfigurable transmission plane. Each unit receiving patch of the receiving layer responds to the right-hand circularly polarized wave irradiated thereon, converts the spatial electromagnetic wave signal into an RF radio frequency current signal, and transmits it to the top radiation layer through the metallized conductive via. Each radiating unit realizes the radiation of a right-hand circularly polarized wave with a specific phase according to the on and off state of the integrated PIN diode. Finally, the right-hand circularly polarized electromagnetic waves radiated by each unit are superimposed in the far field to produce the desired functional beam.

[0077] Fig.16 The bottom receiving layer of the 1-bit circularly polarized reconfigurable transmission array plane is shown. It can be seen that the receiving patches of each unit in the array are arranged in a uniform orientation. In addition, the rectangular patches on both sides of the transmission array plane are used for welding the sockets connected to the FPGA, and each patch is connected to the inner DC bias line layer through a metallized via.

[0078] It should be noted that the compensation phase of each unit radiation patch in the array can be calculated according to the following formula:

[0079]

[0080] Wherein, λ is the wavelength corresponding to the antenna operating frequency, (x, y) is the horizontal and vertical coordinates of the center of each unit in the array, F is the height of the phase center of the normal-placed vertical feed antenna from the plane receiving layer of the transmission array, which is preferably 100 mm, and the focal diameter ratio F / D of the feed and the array is preferably 0.625, where D is preferably the side length of the square reflective surface of 160 mm; is the radiation direction of the transmitted circularly polarized main beam.

[0081] In addition, since the 1-bit circularly polarized reconfigurable transmission unit proposed in the present invention has only two states, state I and state II, and is divided into vertical and horizontal units according to the placement of the PIN diode; therefore, there are two 1-bit phases in the array, with state I of the vertical unit as the phase 0° reference, the vertical unit has two phase states of 0° and 180°; and the horizontal unit has two phase states of 270° and 90°; the compensation phase of each unit in the array is discretized according to the following formula:

[0082]

[0083] Note that, according to the positions of the diodes in the two cells, state I corresponds to two phases of 0° and 270°, and state II corresponds to two phases of 180° and 90°.

[0084] As a functional verification of the 1-bit circularly polarized reconfigurable transmission array antenna system, Fig.17 The transmitted beam pointing is given by Compensated discrete phase distribution diagram, where the discrete phase corresponding to each unit is distinguished by different color blocks, and the phase represented by the specific color block is Fig.17 The pattern above is calibrated; according to the discrete scheme shown in formula (2), the state I corresponding to the two units corresponds to the '0' in the actual FPGA code, and the state II corresponds to the '1' in the actual FPGA code. According to this standard, the discrete phase of the units in the array is converted into the corresponding '0 / 1' coding matrix; the coding matrix is ​​pre-stored in the FPGA chip, and the corresponding voltage signal is distributed to the corresponding unit through the connecting cable.

[0085] Fig.18 , Fig.19 and Fig. 20 The performance curves of the transmission array antenna with fixed transmission beam pointing are given, including the far-field normalized radiation patterns of the co-polarized and cross-polarized transmission components, the gain in the main beam direction and the corresponding aperture efficiency versus frequency, and the axial ratio bandwidth curve in the main beam direction. It can be clearly seen that both the simulation and measured results show that the right-hand circularly polarized beam pointing to the predetermined direction, and the cross-polarization component is less than -20dB, indicating good transmission of right-hand circularly polarized waves; in addition, the measured peak gain in the main beam direction is 18.3dBi, which appears at 9.6GHz, and the corresponding aperture efficiency is as high as 27.5%. Compared with the simulation result corresponding to the peak gain of 19.4dBi at 10.2GHz, the measured result has a certain frequency offset. It is speculated that this is mainly caused by the dielectric constant and thickness deviation of the actual dielectric substrate; it is worth noting that the axial ratio of the main beam is kept below 3dB in the wide bandwidth range of 8.8-12GHz, and the corresponding 3dB axial ratio bandwidth is as wide as 30.8%, indicating that the beam has good polarization purity in the wide bandwidth range.

[0086] To verify the two-dimensional wide-angle beam scanning capability of the 1-bit circularly polarized reconfigurable transmission array antenna system, Fig.21 , Fig. 22 and Fig.23The far-field radiation patterns of the ±60° beam scanning achieved by the array antenna in the diagonal plane (D plane, azimuth angle phi=45°), horizontal plane (E plane, azimuth angle phi=0°) and vertical plane (H plane, azimuth angle phi=90°) under FPGA control, as well as the gain and axial ratio envelope in the main beam direction are given respectively; the phase distributions of the corresponding circularly polarized beams are calculated and discretized according to formulas 1.1 and 1.2, and the deflection direction of the radiation beam of the reconfigurable transmission array antenna can be controlled as needed by pre-storing the corresponding coding matrix in the FPGA and switching with buttons; it can be seen from the three figures that the radiation beam achieves ±60° wide-angle beam scanning with good sidelobe level in two-dimensional space, and the scanning gain loss does not exceed 3.5dB as the angle increases; in addition, the axial ratios of all beam directions are below 3dB, indicating that the beam maintains good polarization purity during scanning.

[0087] The above performance parameters fully demonstrate that the 1-bit circularly polarized reconfigurable transmission unit and array antenna system proposed in the present invention has significant advantages in the application scenarios of low-profile electronically scanned antennas; its advantages such as streamlined structure, controllable manufacturing cost, fast beam response time, and excellent beam performance make it have extremely high application value in scenarios requiring circularly polarized radiation and beam electronic scanning.

[0088] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code. The scheme in the embodiments of the present application can be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0089] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0090] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0091] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0092] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0093] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A broadband, high-efficiency, 1-bit circularly polarized reconfigurable transmission unit, characterized in that: The broadband high-efficiency 1-bit circularly polarized reconfigurable transmission unit includes a circularly polarized wave receiving patch, an upper dielectric substrate, an upper metal ground plane, a DC+ DC bias network, an intermediate dielectric substrate, a DC- DC bias network, a lower metal ground plane, a lower dielectric substrate and a radiation patch arranged in sequence from top to bottom; A C-shaped annular gap is arranged in the center of the circularly polarized wave receiving patch, and two rotationally symmetrical rectangular grooves are etched on the outer ring of the circularly polarized wave receiving patch to receive and reflect the specified circularly polarized wave; The outer circle of the radiation patch is etched with two rotationally symmetrical rectangular grooves, the rectangular grooves of the radiation patch and the rectangular grooves of the receiving patch are in different directions, and a circular ring gap is etched inside to form an inner disc and an outer radiator; the radiation patch bridges the inner disc and the outer radiator by integrating two PIN diodes in the same direction, and only one of the two PIN diodes is selected at a time to selectively connect the inner disc and the outer radiator; The upper metal ground plane and the lower metal ground plane are both pre-punched for transmission of RF radio frequency and DC direct current signals; The DC+ bias network and the DC- bias network are attached to both sides of the intermediate dielectric substrate respectively; one end of the DC+ bias network is connected to the radiator outside the radiation patch through a metallized via and an RF choke inductor, and the other end is connected to the FPGA control board through a socket; the DC- bias network is composed of a fan-shaped open-circuit branch and a bent metal microstrip line connected in series, one end of which is connected to the RF metallized through-hole, and the other end is connected to the metal ground plane through a metallized via; the DC+ bias network and the DC- bias network are respectively connected to the positive and negative ends of the PIN diode to form a complete DC signal path; The receiving patch and the radiating patch are connected through a central metallized through-hole. The spatial electromagnetic wave is received by the receiving patch and converted into a current signal, which is then transmitted to the radiating patch through the metallized through-hole and then transmitted to the outer radiator through the turned-on PIN diode. The current signal is converted into a spatial electromagnetic wave again, thus completing the process of receiving, converting, conducting and re-radiating the spatial electromagnetic signal. The on-off state of the two PIN diodes is controlled by changing the voltage of the DC+ DC bias network, and the 180° phase control is performed on the same circularly polarized radiated electromagnetic wave of the metasurface unit.

2. The broadband high-efficiency 1-bit circularly polarized reconfigurable transmission unit according to claim 1, characterized in that: The metal patches on both sides of the PIN diode are both provided with extension parts.

3. The broadband high-efficiency 1-bit circularly polarized reconfigurable transmission unit according to claim 1, characterized in that: The upper dielectric substrate, the middle dielectric substrate and the lower dielectric substrate are all squares with a side length of 10 mm, and their electrical dimensions do not exceed one half of the working wavelength; The outer rings of the receiving patch and the radiating patch are of the same size so that the resonant frequencies of the two are consistent; The inner metal disc is optimized according to the reception, reflection and radiation characteristics of circularly polarized waves; The slot center of the outer ring maintains a slot angle of 45°, 135°, -45° or -135° with the connection center of the metal microstrip line; the polarization property of the patch unit is changed by adjusting the slot angle.

4. The broadband high-efficiency 1-bit circularly polarized reconfigurable transmission unit according to claim 1, characterized in that: The DC+ bias network uses a 0.2 mm thin metal microstrip line extending in the +x-axis direction; the DC- bias network is composed of a fan-shaped open-circuit branch and a bent metal microstrip line connected in series, one end of which is connected to the RF radio frequency metallized through hole, and the other end is connected to the metal ground plane through the metallized via hole; the metallized via hole is located at a certain distance from the receiving and radiating patches; The fan-shaped open-circuit branch is placed at a distance of one quarter wavelength from the RF radio frequency through hole, and the radius of the fan-shaped open-circuit branch is one quarter wavelength of the operating frequency.

5. The broadband high-efficiency 1-bit circularly polarized reconfigurable transmission unit according to claim 1, characterized in that: The RF radio frequency choke inductor connected to the DC+ direct current bias network is a narrow and long curved metal microstrip line.

6. The broadband high-efficiency 1-bit circularly polarized reconfigurable transmission unit according to claim 1, characterized in that: The DC+ direct current bias network of each unit between the upper metal ground plane and the lower metal ground plane is guided to both sides of the transmission array and uniformly connected to the FPGA control board through a socket.

7. A reconfigurable transmission array antenna using 1-bit metasurface units, characterized in that: The reconfigurable transmission array antenna comprises a circularly polarized planar feed array, a circularly polarized transmission surface and an FPGA control board; The circularly polarized planar feeding array is used to radiate the circularly polarized electromagnetic waves required by the transmission surface; The circularly polarized transmission surface comprises a plurality of 1-bit circularly polarized reconfigurable transmission units as described in claims 1 to 6, wherein the 1-bit circularly polarized reconfigurable transmission units are arranged in an n×n array, and adjacent 4×4 1-bit circularly polarized reconfigurable transmission units constitute a supercell, wherein the supercell is formed by rotating and replicating a 2×2 structural block, wherein the 2×2 structural blocks are arranged in an orthogonal rotation manner, and the two 1-bit circularly polarized reconfigurable transmission units before and after rotation constitute two orthogonal units according to the placement orientation of the diode, and the 1-bit phase before the unit rotation is 0° and 180°; and the 1-bit phase after the unit rotation is 270° and 90°; The FPGA control board allocates different bias voltages to each 1-bit circularly polarized reconfigurable transmission unit in the circularly polarized transmission plane, and performs phase-independent control on n×n 1-bit circularly polarized reconfigurable transmission units, so that the reconfigurable transmission array antenna performs ±60° large-angle beam scanning in a two-dimensional half space.

8. The reconfigurable transmission array antenna according to claim 7, characterized in that: The circularly polarized planar feed array antenna is composed of 2×2 corner-cut square patches, and the energy is evenly distributed to four corner-cut square patches arranged in a rotational manner in the order of 0°, 90°, 180° and 270° through a ring series feed network to form a broadband planar feed array antenna with a three-dimensional symmetrical circularly polarized radiation beam shape; The bottom of the circularly polarized planar feed array antenna is a complete metal ground plane, and the top layer is covered with a super-surface impedance matching layer composed of a plurality of small metal square pieces to achieve wide-angle impedance matching.

9. The reconfigurable transmission array antenna according to claim 7, characterized in that: The FPGA control board is connected to the DC+ DC bias network concentrated on both sides of the transmission array antenna through a total of 16 sockets on both sides; one socket on the left side controls two rows of n / 2 1-bit metasurface units on the left side of the corresponding row, and one socket on the right side controls two rows of n / 2 1-bit metasurface units on the right side of the corresponding row; the calculated beam phase coding is pre-stored in the FPGA control board.

10. The reconfigurable transmission array antenna according to claim 7, characterized in that: The n is equal to 16, the circularly polarized planar feed array radiates right-handed circularly polarized electromagnetic waves, the distance between the feed source phase center and the transmission array is set to 100 mm, and the focal diameter ratio is 0.625, so as to irradiate each receiving patch of the transmission array; the transmission array mirror-reflects left-handed circularly polarized electromagnetic waves and receives right-handed circularly polarized electromagnetic waves, and controls the phase of the electromagnetic waves re-radiated by each metasurface unit through the FPGA control board, so as to perform reconfigurable and efficient directional radiation of the transmitted right-handed circularly polarized waves.

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