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

Abstract

The application discloses a broadband high-efficiency 1bit circularly polarized reconfigurable transmission unit and array antenna, the reconfigurable transmission unit comprises, from top to bottom, a circularly polarized wave receiving patch, an upper layer dielectric substrate, an upper layer metal ground plane, an intermediate dielectric substrate, a DC bias line, a lower layer metal ground plane, a lower layer dielectric substrate and a radiation patch, and the reconfigurable transmission unit can directly realize 0° and 180° two kinds of unit phases of the circularly polarized transmission wave, and the equivalent rotating phase is non-dispersive; the state of each unit in the transmission array is controlled through an FPGA, ±60° large-angle scanning of the circularly polarized transmission beam can be realized, the beam performance is good, and the circularly polarized purity is high. The array antenna has the advantages of wide axial ratio bandwidth and high aperture efficiency, and has high application potential and value in the scene requiring real-time electrically-controlled circularly polarized beam scanning antennas, such as long-distance radar detection and communication systems and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of microwave and antenna technology, in particular to a wideband high-efficiency 1bit circularly polarized reconfigurable transmission unit and array antenna. BACKGROUND

[0002] Circularly polarized antennas, as an important part of long-distance radar detection and wireless communication systems, have attracted extensive research attention due to their advantages in resisting path loss, Faraday rotation and multipath effects. However, with the development of technology, the requirement of real-time high-performance circularly polarized beam scanning makes it difficult for traditional mechanical scanning and electronic scanning antennas with additional phase shifter networks to meet the actual application requirements. Due to some inherent defects, such as heavy mechanical structure and expensive phase shifter network, the traditional scanning method has gradually withdrawn from the researchers' field of vision in the trend of modern low-cost, lightweight and easy-to-integrate devices.

[0003] The existing metasurface design can realize flexible control of electromagnetic wave amplitude, phase and polarization by integrating diodes or MEMS micro-electro-mechanical systems, thereby realizing low-cost, low-profile and easy-to-integrate antenna devices, which basically meet 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 simple linearly polarized wave phase control. Such antenna devices are easily affected by spatial path fading, and due to the existence of multipath effects, the detection and communication quality of such devices is reduced.

[0004] The emergence of reconfigurable circularly polarized array antennas can effectively solve the above problems and has significant advantages in radar anti-jamming and other application fields. However, most of the existing circularly polarized array antennas are limited to the category of reflective array antennas, which usually require a higher profile feed antenna on the same side of the beam scattering direction, resulting in significant feed blockage and high profile problems. Therefore, there are few reported circularly polarized reconfigurable transmission arrays appearing in the field of vision of researchers. However, the existing circularly polarized transmission arrays have great difficulties in the design of reconfigurable metasurface units on the one hand, and the complex multi-device integration and structure make it difficult to be applied to practical applications. In addition, whether it is a reconfigurable circularly polarized reflective array or a transmission array, it is 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 the problem of multi-layer complex structure and integration of more devices. With the development of measurement and control technology, lightweight and easy-to-integrate antenna systems also need to have large-angle beam scanning capability, which is more difficult for circularly polarized antennas. Therefore, in various practical application scenarios, there are still many problems to be solved in reconfigurable circularly polarized array antennas. SUMMARY

[0005] The application aims to provide a broadband high-efficiency 1bit circularly polarized reconfigurable transmission unit and array antenna, which realizes phase control of circularly polarized waves by only relying on a single functional layer, thereby solving the problem of complex structure of existing circularly polarized transmission units; in addition, a broadband planar circularly polarized feeding array, a broadband and high-efficiency circularly polarized unit and a specific unit arrangement scheme in the array, the three are matched to make the 1bit circularly polarized reconfigurable transmission array antenna have wideband, high-efficiency and good polarization purity wide-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 and compact integration.

[0006] To achieve the above technical purposes, the technical scheme adopted by the application is:

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

[0008] The central part of the circularly polarized wave receiving patch is provided with a C-shaped ring slot, and the outer circle of the circularly polarized wave receiving patch is etched with two rotationally symmetrical rectangular grooves to receive and reflect specified circularly polarized waves.

[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 receiving patch are inconsistent in direction, the inner part is etched with a circular ring gap, forming an inner circular patch and an outer radiator; the radiation patch bridges the inner circular patch and the outer radiator by integrating two PIN diodes with consistent direction, and only one of the two PIN diodes is selected at one time to selectively connect the inner circular patch and the outer radiator.

[0010] The upper layer metal ground plane and the lower layer metal ground plane are both provided with pre-punching for transmission of RF and DC signals.

[0011] The DC+ direct current bias network and the DC- direct current bias network are respectively attached to the two sides of the middle dielectric substrate; one end of the DC+ direct current bias network is connected to the outer side radiator of the radiation patch through a metallized via and an RF choke inductance, and the other end is connected to the FPGA control board through a socket; the DC- direct current bias network is mainly composed of a fan-shaped open-circuit stub and a bent metal microstrip line connected in series, one end of which is connected to an RF metallized via, and the other end is connected to a metal ground plane through a metallized via; the DC+ direct current bias network and the DC- direct current bias network are respectively connected to the positive and negative electrodes of the PIN diode, forming a complete DC direct current signal path.

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

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

[0014] Further, the upper dielectric substrate, the middle dielectric substrate and the lower dielectric substrate are all square with a side length of 10 mm, and the electrical size is not more than one half of the working wavelength.

[0015] The outer circle rings of the receiving patch and the radiation patch are the same size to make the resonant frequencies consistent. The inner metal disc is optimized according to the receiving, reflecting and radiating characteristics of the circularly polarized wave. The center of the outer slot and the center of the metal microstrip line are kept at a slot included angle of 45°, 135°, -45° or -135°. The polarization properties of the patch unit are changed by adjusting the slot included angle.

[0016] Further, the DC+ direct current bias network adopts a 0.2 mm long metal microstrip line extending in the +x direction; the DC- direct current bias network is composed of a fan-shaped open-circuit stub and a bent metal microstrip line connected in series, one end of which is connected to an RF metallized via, and the other end is connected to a metal ground plane through a metallized via; the position of the metallized via is kept at a certain distance from the receiving and radiation patches.

[0017] The fan-shaped open-circuit stub is placed at a distance of one quarter of the wavelength of the RF frequency from the RF via, and the radius of the fan-shaped open-circuit stub is one quarter of the wavelength of the working frequency.

[0018] Further, the RF choke inductance connected to the DC bias network can be replaced by a long and curved metal microstrip line.

[0019] Further, the 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 connected to the FPGA control board through the socket.

[0020] In a second aspect, the application discloses a reconfigurable transmission array antenna using 1bit metasurface units, which comprises a circularly polarized planar feed array, a circularly polarized transmission surface and an FPGA control board.

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

[0022] The circularly polarized transmission surface comprises a plurality of 1bit circularly polarized reconfigurable transmission units arranged in an n×n array, and adjacent 4×4 1bit circularly polarized reconfigurable transmission units form a supercell, the supercell is formed by rotating and copying 2×2 structure blocks, the 2×2 structure blocks are arranged in an orthogonal rotation mode, and the two kinds of 1bit circularly polarized reconfigurable transmission units before and after rotation constitute two kinds of units in an orthogonal manner according to the placement direction of the diodes, and the 1bit phase before unit rotation is 0° and 180°; the 1bit phase after unit rotation is 270° and 90°.

[0023] The FPGA control board allocates different bias voltages for each 1bit circularly polarized reconfigurable transmission unit in the circularly polarized transmission surface, and independently controls the phases of the n×n 1bit circularly polarized reconfigurable transmission units, so that the reconfigurable transmission array antenna performs ±60° wide-angle beam scanning in a two-dimensional half space.

[0024] Further, the circularly polarized planar feed array antenna is composed of 2×2 cut-corner square patches, energy is evenly divided to the four cut-corner square patches arranged in a rotation mode of 0°, 90°, 180° and 270° through a ring-shaped series feed network, so as to form a planar feed array antenna with wideband and 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 is covered with a metasurface impedance matching layer composed of a plurality of small metal squares, so as to realize wide-angle impedance matching.

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

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

[0028] Compared with the prior art, the beneficial effects of the present application are as follows:

[0029] Firstly, the wideband and high-efficiency 1bit circularly polarized reconfigurable transmission unit and array antenna of the present application realizes the phase control function of wideband and high-efficiency 1bit circularly polarized electromagnetic waves with the least two PIN diodes and a single-layer phase control function layer required by the transmission unit, greatly simplifying the structure and design complexity of the circularly polarized reconfigurable transmission array.

[0030] Secondly, the wideband and high-efficiency 1bit circularly polarized reconfigurable transmission unit and array antenna of the present application adopts a 4x4 orthogonal rotation supercell in the unit of the reconfigurable transmission array, which can eliminate the main polarization sidelobe caused by 1bit phase quantization error and eliminate the stray sidelobe of the cross-polarization component formed by the mirror, so that the main polarization component is effectively converged in the main beam direction to improve the beam gain and aperture efficiency, and the axial ratio bandwidth of the circularly polarized beam is also significantly widened.

[0031] Thirdly, the wideband and high-efficiency 1bit circularly polarized reconfigurable transmission unit and array antenna of the present application uses a circularly polarized planar array antenna as the feed source of the reconfigurable circularly polarized transmission array antenna, which can realize wideband symmetric 3D radiation beam irradiation, and is easy to integrate into a lightweight and low-profile antenna system, making the radar or communication system more compact.

[0032] Fourthly, the wideband and high-efficiency 1bit circularly polarized reconfigurable transmission unit and array antenna of the present application uses a high-speed FPGA control board to realize the rapid switching of the state of the array unit, so as to change the phase distribution on the aperture surface, realize the scanning of ±60° large-angle beam in two-dimensional half space, and is very suitable for communication and detection systems that require rapid and instant scanning beams. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 A structure schematic diagram of a broadband high-efficiency 1bit circularly polarized reconfigurable transmissive unit proposed by the application;

[0034] Figure 2 A top view of the 1bit circularly polarized reconfigurable transmissive unit shown in the figure, specifically the receiving patch structure; Figure 1

[0035] Figure 3 A bottom view of the 1bit circularly polarized reconfigurable transmissive unit shown in the figure, specifically the radiation patch structure, including two integrated PIN diodes and one RF choke inductor; Figure 1

[0036] Figure 4 A DC+ and DC- direct current bias network schematic diagram of the 1bit circularly polarized reconfigurable transmissive unit;

[0037] Figure 5 A metal ground plane structure schematic diagram;

[0038] Figure 6 A reflection and transmission co-polarization and cross-polarization component amplitude response curve of the 1bit circularly polarized reconfigurable transmissive unit when the left-handed circularly polarized electromagnetic wave is normally irradiated to the unit receiving patch;

[0039] Figure 7 A reflection and transmission co-polarization and cross-polarization component amplitude response curve of the 1bit circularly polarized reconfigurable transmissive unit when the right-handed circularly polarized electromagnetic wave is normally irradiated to the unit receiving patch;

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

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

[0042] Figure 10 A schematic diagram of the main radiator (Figure (a)) and a schematic diagram of the super surface wide-angle impedance matching layer (Figure (b)) of the circularly polarized planar feed array antenna;

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

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

[0045] Figure 13 Schematic diagram of a 4x4 supercell composed of two kinds of units arranged orthogonally (a), and a corresponding actual diagram (b);

[0046] Figure 14 Schematic diagram of a 16x16 unit arrangement of a 1bit circularly polarized reconfigurable transmissive array antenna realized by the application;

[0047] Figure 15 Schematic diagram of the working principle of a 1bit circularly polarized reconfigurable transmissive array antenna system, including a planar feed antenna and a transmissive array;

[0048] Figure 16 Bottom view of a 1bit circularly polarized reconfigurable transmissive array, specifically including a schematic diagram of a receiving patch distribution and a socket interface on both sides for connecting an FPGA;

[0049] Figure 17 Aperture phase distribution diagram of a fixed angle transmissive beam of a 1bit circularly polarized reconfigurable transmissive array antenna system;

[0050] Figure 18 Far field normalized radiation pattern of a fixed beam of a 1bit circularly polarized reconfigurable transmissive array antenna system;

[0051] Figure 19 Gain and corresponding aperture efficiency curves of a fixed beam of a 1bit circularly polarized reconfigurable transmissive array antenna system with respect to frequency;

[0052] Figure 20 Axial ratio bandwidth curve of the main beam radiation direction of a fixed beam of a 1bit circularly polarized reconfigurable transmissive array antenna system;

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

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

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

[0056] In the drawings:

[0057] 1. Right-handed circularly polarized receiving patch; 2. Right-handed circularly polarized radiating patch; 3. PIN diode; 4. RF choke inductance; 5. RF metallized via; 6. Upper layer dielectric substrate; 7. Middle layer dielectric substrate; 8. Lower layer dielectric substrate; 9. Upper layer metal ground plane; 10. Lower layer metal ground plane; 11. DC-bias network composed of fan-shaped branches and bent microstrip lines; 12. DC- metallized via; 13. DC+ bias network and metallized via; 14. Dielectric substrate pp adhesive layer; 15. Dielectric substrate pp adhesive layer; 16. Circularly polarized planar feed array antenna main radiator patch; 17. Planar feed array antenna ring-shaped series feed network; 18. Super surface wide-angle impedance matching layer; 19. Planar feed array antenna metal ground plane; 20. Feed antenna lower layer dielectric substrate; 21. Feed antenna upper layer dielectric substrate; 22. Feed antenna central SMA micro connector feed schematic. DETAILED DESCRIPTION

[0058] The embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0059] As Figure 1 shown, the present application discloses a broadband high-efficiency 1bit circularly polarized reconfigurable transmissive unit, from top to bottom, in turn, right-handed circularly polarized receiving patch 1, upper layer dielectric substrate 6, upper layer metal ground plane 9, DC+ bias network and metallized via 13, middle layer dielectric substrate 7, DC-bias network 11 composed of fan-shaped branches and bent microstrip lines, lower layer metal ground plane 10, lower layer dielectric substrate 8, and right-handed circularly polarized radiating patch 2 integrated with RF choke inductance 4 and PIN diode 3; three layers of dielectric substrates are adhered by pp adhesive layers 14 and 15; central metallized via 5 penetrates all dielectric and two layers of metal ground planes, connecting right-handed circularly polarized receiving patch 1 and right-handed circularly polarized radiating patch 2 for the conduction of RF signals.

[0060] All dielectric substrates and metal ground planes are preferably square with a side length of 10mm in the X-band range, which is one third of the center operating frequency wavelength, and the preferred size is no more than 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 significant 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 the metal patches under a specific unit size, the selection of the more common and relatively inexpensive F4B material is beneficial to reducing the cost of the entire transmission array antenna.

[0062] The specific structure of the top right-hand circularly polarized receiving patch 1 is as follows Figure 2 As shown, a C-shaped annular gap 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, it is at a 45° angle here. It should be noted that the effect of this bridging metal microstrip line is the same when placed on the right side horizontally; 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 for explanation and does not limit the function of the receiving patch.

[0063] Figure 3The structure shown is a top layer right-handed circularly polarized radiation patch 2, two rotationally symmetric rectangular slots are etched in the outer ring, the internal is etched with a circular ring slot, and the internal and external patches are bridged by integrating two PIN diodes, for easy welding, the metal patches on the left and right sides of the PIN diodes are partially extended. The inner side of the radiation patch 2 and the outer ring radiation circular patch are physically isolated, and the two rectangular slots of the outer ring circular patch have a similar mechanism to the receiving patch; through the selective connection of the integrated two PIN diodes 3, the radiation of the same polarized wave with different phases is realized; similarly, placing the PIN diode vertically can change the polarization characteristics of the radiated electromagnetic wave; the voltage controlling the on-off state of the PIN diode is applied to the outer ring radiation circular patch through the RF choke inductance 4, and the isolation of the RF signal and the DC bias network is ensured. The two PIN diodes integrated in the radiation patch are selected at a time, and the on-off state of the two PIN diodes can be controlled by changing the DC bias voltage, which can realize the 180° phase control of the same circularly polarized radiation electromagnetic wave of the metasurface unit; among them, the phase is 0° when the two diodes are in state I (ON / OFF), and the phase is 180° when the two diodes are in state II (OFF / ON); the two states are controlled by applying different voltages through a single DC+ bias line; the two states can be equivalent to a physically rotating realized by electrical control, so it has the characteristics of wideband phase control without dispersion. The outer ring of the receiving patch and the radiation patch is the same size, ensuring that the resonant frequencies of the two are consistent; the inner metal disc can be optimized according to the receiving, reflecting and radiating characteristics of the circularly polarized wave. The center of the outer slot is connected to the center of the metal microstrip line at an angle of 45° or 135°, which can achieve ideal circular polarization characteristics; if you want to change the polarization properties of the patch unit, the slot angle can be selected at -45° or -135°.

[0064] Figure 4 The structure shown is a DC-bias network 11, which is attached to the intermediate layer dielectric substrate 7, which is isolated by the metal ground planes 9 and 10 on both sides, and can theoretically choose any thickness and any material. Here, to ensure the continuity of impedance, the same F4B material is still chosen, with a height of 0.508 mm; the DC-bias network 11 is composed of a fan-shaped open-circuit stub and a curved metal microstrip line in series, which can be equivalent to a low-pass filter. The two ends are connected to the RF signal conducting hole and the metal ground plane respectively, which prevents RF signal leakage.

[0065] Figure 5 The detailed structure of the two metal ground planes 9 and 10 is shown. The central white hole allows RF signals to pass through, and the lower white hole allows DC bias voltage signals to pass through. Figure 5The red dots in the same position are the metalized via connecting different functional metal patches. The two layers of metal ground planes are pre-perforated 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 anode of the left PIN diode is connected to the external patch, and the cathode is connected to the internal patch. The anode of the right PIN diode is connected to the internal patch, and the cathode is connected to the external patch. The external patch is connected to the DC bias network through an RF choke inductor. Placing the two layers of DC bias networks in the middle of the two layers of metal ground planes can effectively eliminate their influence on the receiving or radiating patch. If the structure is to be simplified, a single layer of metal ground plane can be used to isolate the receiving and radiating patches. An elongated and curved microstrip line and a fan-shaped open-circuit stub connected to the DC bias network form an equivalent low-pass filter, which effectively prevents the leakage of RF signals and allows the passage of DC signals. The RF choke inductor connected to the DC bias network can be replaced by an elongated and curved microstrip line. In this embodiment, the DC bias network uses a 0.2mm elongated metal microstrip line extending in the +x direction and connected to the fan-shaped stub. The fan-shaped stub is placed at a distance of one-quarter wavelength from the RF via. The fan-shaped stub has an opening angle of 80°. The larger the opening angle, the wider the bandwidth of the RF current signal leakage suppression. The radius of the fan-shaped stub is one-quarter of the wavelength of the operating frequency. To make the structure compact, the elongated and curved metal line is placed along the -y axis. The width and gap of the curved line are both 0.2mm, and it is connected to the metal ground plane through a metalized via. The position of the metalized via must ensure a certain distance from the receiving and radiating patches. The radiating patch is connected to the DC bias network in the middle of the ground plane through an RF choke inductor and a metalized via. The choke inductor can be replaced by an elongated and curved metal line. In order to independently distribute different DC voltages to each unit, the DC bias network of each unit between the two ground planes is guided to both sides of the transmission array and is connected to the FPGA control board through a socket.

[0067] As a functional explanation of the working mechanism of the above unit, Figure 6 and Figure 7The scattering and transmission amplitude response curves of the super surface unit structure are shown when the left-handed circular polarized wave and the right-handed circular polarized wave are vertically irradiated to the top layer receiving patch of the unit respectively; when the left-handed circular polarized wave is incident, the unit realizes efficient rLL co-polarized reflection, the reflection loss is less than 1 dB in the wideband range of 9.5-10.5 GHz, and almost no energy is converted into cross-polarized component reflection or transmitted to the other side; when the right-handed circular polarized wave is incident, the unit realizes efficient tRR co-polarized transmission, the insertion loss is less than 1.5 dB in the wideband range of 9.7-10.5 GHz, and almost no energy is reflected or converted into cross-polarized component transmission, the cross-polarized transmission component is less than -15 dB in the range of 9.8-10.4 GHz; 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), 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 super surface unit has a 1bit phase control function, Figure 8 The co-polarized and cross-polarized transmission amplitude responses of the unit when the right-handed circular polarized wave is incident, and the corresponding co-polarized transmission component phase response curves when the super surface unit works in two different states (state I and state II) are shown; it can be seen that the transmission amplitude responses in the two states are basically consistent, but the phase difference is kept near 180° in the entire X-band of 8-12 GHz; in fact, the two working states of the unit can be equivalent to a physical rotation of 180°, and such an equivalent rotation phase realized in an electrically controlled manner is non-dispersive, and theoretically the phase difference between the two is 180° at any frequency, which guarantees the wideband phase modulation capability of the 1bit super surface unit described in the present application.

[0069] The application also provides a reconfigurable transmissive array antenna using 1bit metasurface units, which comprises a circularly polarized planar feed array and a circularly polarized receiving and radiating transmissive surface; the circularly polarized planar feed array radiates the circularly polarized electromagnetic waves required by the transmissive surface; the 1bit metasurface units are arranged in an n*n array in a specific 4*4 structure block to construct the transmissive surface; and different bias voltages are distributed to each 1bit unit in the transmissive surface through an FPGA control board, so that the phase of the n*n units can be controlled independently, thereby enabling the reconfigurable transmissive array antenna to realize efficient ±60° wide-angle beam scanning in a two-dimensional half space. The circularly polarized planar feed array antenna is composed of a 2*2 classical cut-corner square patch, and the energy is evenly divided to four cut-corner square patches arranged in a sequentially rotating manner through a ring-shaped series feed network, so as to form a planar feed array antenna with wideband and three-dimensional symmetrical circularly polarized radiation beam shape; and a complete metal ground plane is arranged at the bottom of the feed array antenna, and a metasurface impedance matching layer composed of a plurality of small metal squares is arranged on the top layer, so as to realize wide-angle impedance matching.

[0070] Specifically, in order to realize a wideband and high-efficiency circularly polarized reconfigurable transmissive array antenna, in addition to the wideband and high-efficiency unit performance, the performance of the feed antenna also has an important influence on the performance of the overall reconfigurable transmissive array antenna; the feed antenna is optimally arranged, and the main radiation patch 16 and the ring-shaped series feed network 17 form a small 2*2 circularly polarized planar array antenna; the ring-shaped series feed network 17 ensures that the energy fed by the center single-end SMA connector 22 is evenly divided to four rectangular cut-corner patches arranged in a sequentially rotating manner at 0°, 90°, 180° and 270°, so as to realize effective superposition of the desired circularly polarized wave; the metasurface wide-angle impedance matching layer 18 attached to the top of the upper layer 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 layer dielectric substrate 20; and the inner core probe of the center single-end SMA connector 22 penetrates through the metal ground plane and is connected with the central connection of the ring-shaped series feed network 17. Figure 9 The three-dimensional exploded view and the side view of the 2*2 circularly polarized planar feed array antenna are shown; and the main radiator patch and the metasurface wide-angle impedance matching layer are shown in Figure 10 .

[0071] The 4*4 structure sub-blocks arranged in a specific pattern are used for the transmissive surface, which can effectively eliminate the co-polarized sidelobe problem caused by 1bit quantization error, and further eliminate the cross-polarization component in the mirror image to form a stray sidelobe, so that the energy can converge in the main beam direction, thereby greatly increasing the radiation gain and aperture efficiency of the transmissive array antenna;

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

[0073] As a preferred parameter example of the circularly polarized planar feed array antenna, Figure 11 The reflection coefficient S 11 And the gain and axial ratio characteristic curve of the right-handed circularly polarized wave; it can be seen that the measured reflection coefficient is maintained below-10dB in the wide frequency band 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 or more in the wide band 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 the main radiator patch layer can be easily folded by mirroring to obtain a left-handed circularly polarized wave radiation antenna with similar performance.

[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, which are Figure 12 The PIN diode is vertically placed as a vertical unit and horizontally placed as a horizontal unit, and is represented by the lower right corner letter 'V' and 'H' respectively; the two types of units are placed according to Figure 13 The orthogonal rotation pattern is shown, and a 4x4 structure block supercell is formed; a 1bit circularly polarized reconfigurable transmission array antenna example is a collection of 16x16 units composed of 4x4 such structure block supercells, and the structure pattern of each unit in the array is shown as Figure 14 .

[0075] Figure 15 The overall structure diagram of the 1bit circularly polarized reconfigurable transmission array antenna system as an example of the application is shown, which is composed of a right-handed circularly polarized planar feed array antenna placed below and a reconfigurable transmission plane above, of course, which 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-handed circularly polarized planar feed array antenna radiates a three-dimensional symmetrical right-handed circularly polarized wide beam, which is irradiated to the receiving layer of the reconfigurable transmission plane, each unit of the receiving layer receives the right-handed circularly polarized wave irradiated on the receiving patch and responds to the right-handed circularly polarized wave, converts the spatial electromagnetic wave signal into an RF radio frequency current signal, and conducts the RF radio frequency current signal to the top radiation layer through the metalized conductive via, and each radiation unit realizes the radiation of the right-handed circularly polarized wave with a specific phase according to the on and off states of the integrated PIN diode, and finally the right-handed circularly polarized electromagnetic waves radiated by each unit form a superposition in the far field to generate a desired functional beam.

[0077] Figure 16 The bottom layer receiving layer of the 1bit circularly polarized reconfigurable transmission array plane is shown, and it can be seen that the receiving patches of each unit in the array are arranged in a unified direction, and in addition, the rectangular patches on both sides of the transmission array plane are used for soldering the sockets of the FPGA, wherein each patch is connected to the inner layer DC bias line layer through a metalized via.

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

[0079] Wherein, λ is the wavelength corresponding to the working frequency of the antenna, (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 vertically placed feed antenna from the receiving layer of the transmission array plane, which is preferably 100 mm, and the focal ratio F / D of the feed and the array is preferably 0.625, wherein D is preferably the side length of the square reflecting surface, 160 mm; is the radiation direction of the transmission circularly polarized main beam.

[0080] In addition, since the 1bit circularly polarized reconfigurable transmission unit proposed in the present application has only two states, state I and state II, and is divided into vertical and horizontal units according to the position of the PIN diode, the array has two 1bit phases, with the 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:

[0081] Note that according to the position of the diode in the two units, state I corresponds to two phases of 0° and 270°, and state II corresponds to two phases of 180° and 90°.

[0082] As a functional verification of the 1bit circularly polarized reconfigurable transmission array antenna system, Figure 17 The transmission beam pointing direction is given The compensation discrete phase distribution diagram, wherein each unit corresponds to a discrete phase distinguished by different color blocks, and the phase represented by a specific color block is shown in the table below Figure 17 The upper pattern calibration; according to the discrete scheme shown in formula (2), the state I corresponding to two units corresponds to '0' in the actual FPGA code, and the state II corresponds to '1' in the actual FPGA code, and the unit discrete phase in the array is converted into the corresponding '0 / 1' code matrix according to this standard; the code matrix is pre-stored in the FPGA chip, and the corresponding voltage signal is distributed to the corresponding unit through the connecting cable.

[0083] Figure 18 、 Figure 19 and Figure 20 The performance curves of the transmissive array antenna with fixed transmissive beam pointing are given, including the far-field normalized radiation patterns of co-polarization and cross-polarization transmission components, the gain and corresponding aperture efficiency curves with frequency variation in the main beam direction, and the axial ratio bandwidth curve in the main beam direction; obviously, both the simulation and the measured results show that the right-handed circularly polarized beam points to the predetermined direction, and the cross-polarization component is less than -20 dB, indicating good transmission of right-handed circularly polarized waves; in addition, the measured peak gain of the main beam direction is 18.3dBi, which occurs at 9.6GHz, and the corresponding aperture efficiency is as high as 27.5%, compared with the corresponding 10.2GHz peak gain of 19.4dBi in the simulation result, the measured result appears a certain frequency shift, which is mainly caused by the deviation of the dielectric constant and thickness of the actual medium substrate; it is worth noting that the axial ratio of the main beam remains below 3dB in the wide frequency band 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 frequency band.

[0084] To verify the two-dimensional wide-angle beam scanning capability of the 1bit circularly polarized reconfigurable transmissive array antenna system, Figure 21 、 Figure 22 and Figure 23The far-field radiation patterns of the array antenna in the diagonal section (D-plane, azimuth angle phi = 45°), the horizontal section (E-plane, azimuth angle phi = 0°) and the vertical section (H-plane, azimuth angle phi = 90°) for realizing the ±60° beam scanning are respectively given under the control of the FPGA, and the gain and axial ratio envelope of the main beam direction are also given. The phase distribution corresponding to the circularly polarized beam is calculated and discretized according to the formulas 1.1 and 1.2, and the corresponding encoding matrix is pre-stored in the FPGA, and the deflection direction of the reconfigurable transmissive array antenna radiation beam can be controlled as needed by switching the keys. As can be seen from the three figures, the radiation beam realizes the ±60° wide-angle beam scanning with good side lobe level in the two-dimensional space, and the gain loss is not more than 3.5dB as the angle increases. In addition, the axial ratio of all beam directions is below 3dB, indicating that the beam maintains good polarization purity during scanning.

[0085] The above performance parameters fully demonstrate that the 1bit circularly polarized reconfigurable transmissive unit and array antenna system proposed in the application have significant advantages in the application scenario of low-profile electrically scanned antennas. The advantages of simple 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 electrically controlled beam scanning.

[0086] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system or a computer program product. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware aspects. Moreover, the present application can take 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.) containing computer usable program code. The solutions in the embodiments of the present application can be implemented in various computer languages, such as object-oriented programming language Java and interpreted scripting language JavaScript.

[0087] The present application is described with reference to flowcharts and / or block diagrams according to the methods, devices (systems) and computer program products of the embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of the flows and / or blocks in the flowcharts and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device produce a device that implements the functions specified in the flowcharts and / or block diagrams. Figure 1 The functions specified in one flow or multiple flows and / or blocks Figure 1 The device that implements the functions specified in one flow or multiple flows and / or blocks.

[0088] These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the Figure 1 function specified in the flow or flows and / or blocks Figure 1 of the block or blocks.

[0089] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions that are executed on the computer or other programmable apparatus provide steps for implementing the Figure 1 function specified in the flow or flows and / or blocks Figure 1 of the block or blocks.

[0090] Although preferred embodiments of the application have been described herein, substitutions and alterations are possible in view of the disclosure of this application without departing from the spirit and scope of the present application. Therefore, it is the intent of the appended claims to cover all such variations and modifications as come within the scope of the present application. 1

[0091] It will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the spirit or scope of the application. Thus, it is intended that the present application cover modifications and variations of this application provided they come within the scope of the appended claims and their equivalents.

Claims

1. A broadband high-efficiency 1-bit circularly polarized reconfigurable transmissive unit, characterized in that, The broadband high-efficiency 1bit circularly polarized reconfigurable transmission unit comprises, from top to bottom, a circularly polarized wave receiving patch, an upper layer dielectric substrate, an upper layer metal ground plane, a DC+ direct current bias network, an intermediate dielectric substrate, a DC- direct current bias network, a lower layer metal ground plane, a lower layer dielectric substrate and a radiation patch; the circularly polarized wave receiving patch and the radiation patch are both circular; The central part of the circularly polarized wave receiving patch is provided with a C-shaped ring gap, forming an outer ring structure and a central circular patch, the outer ring structure and the central circular patch are bridged by a metal microstrip line, and the outer ring of the circularly polarized wave receiving patch is etched with two rotationally symmetrical rectangular grooves to receive and reflect the specified circularly polarized wave; The outer ring of the radiation patch is etched with two rotationally symmetrical rectangular grooves, the rectangular grooves of the radiation patch and the receiving patch are inconsistent in direction, and the inside is etched with a circular ring gap, forming an inside circular patch and an outside radiator; the radiation patch bridges the inside circular patch and the outside radiator by integrating two PIN diodes with consistent direction, and only one of the two PIN diodes is selected at one time to selectively connect the inside circular patch and the outside radiator; The upper layer metal ground plane and the lower layer metal ground plane are both provided with pre-punching for transmission of RF radio frequency and DC direct current signals; The DC+ direct current bias network and the DC- direct current bias network are respectively attached to the two sides of the intermediate dielectric substrate; one end of the DC+ direct current bias network is connected to the outside radiator of the radiation patch through a metallized via and an RF radio frequency choke inductor, and the other end is connected to an FPGA control board through a socket; the DC- direct current 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 an RF radio frequency metallized via, and the other end is connected to a metal ground plane through a metallized via; the DC+ direct current bias network and the DC- direct current bias network are respectively connected to the positive and negative electrodes of the PIN diode, forming a complete DC direct current signal path; The receiving patch and the radiation patch are connected through the central RF radio frequency metallized via, the spatial electromagnetic wave is received by the receiving patch and converted into a current signal, which is conducted to the radiation patch through the metallized via, and then conducted to the outside radiator through the conducting PIN diode, and the current signal is converted into a spatial electromagnetic wave again, completing the receiving, conversion, conduction and re-radiation process of the spatial electromagnetic signal; by changing the voltage of the DC+ direct current bias network, the on-off state of the two PIN diodes is controlled, and the same circularly polarized radiation electromagnetic wave of the metasurface unit is phase-controlled by 180°.

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

3. The broadband high-efficiency 1-bit circularly polarized reconfigurable transmission unit of claim 1, wherein The upper layer dielectric substrate, the intermediate dielectric substrate and the lower layer dielectric substrate are all square with a side length of 10 mm, and the electrical size is not more than one half of the working wavelength; The outer ring of the receiving patch and the radiation patch is the same size, so that the resonant frequencies of the two are consistent; The inside metal circular patch is optimized according to the receiving, reflecting and radiating characteristics of the circularly polarized wave; The outer ring is connected to the center of the metal microstrip line with a slotted center at an angle of 45°, 135°, -45° or -135°; the polarization properties of the patch unit are changed by adjusting the slotted angle.

4. The broadband high-efficiency 1-bit circularly polarized reconfigurable transmission unit of claim 1, wherein The DC+ bias network adopts a 0.2mm long and narrow metal microstrip line extending in the +x-axis direction. The fan-shaped open-circuit stub is placed at a quarter wavelength away from the RF metalized via, and the radius of the fan-shaped open-circuit stub is a quarter wavelength of the working frequency.

5. The broadband high-efficiency 1-bit circularly polarized reconfigurable transmission unit of claim 1, wherein The RF choke inductance connected to the DC+ bias network is a long and narrow metal microstrip line.

6. The broadband high-efficiency 1-bit circularly polarized reconfigurable transmission unit of claim 1, wherein The DC+ bias network of each unit between the upper and lower metal ground planes is guided to both sides of the transmission unit and connected to the FPGA control board through the sockets.

7. A reconfigurable transmissive array antenna employing 1-bit metasurface unit, 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 feed array is used to radiate circularly polarized electromagnetic waves required by the transmission surface. The circularly polarized transmission surface comprises a plurality of 1bit circularly polarized reconfigurable transmission units according to any one of claims 1 to 6, the 1bit circularly polarized reconfigurable transmission units are arranged in an n×n array, and adjacent 4×4 1bit circularly polarized reconfigurable transmission units form a supercell, the supercell is formed by rotating and copying a 2×2 structure block, the 2×2 structure block is arranged in an orthogonal rotation manner, and two kinds of 1bit circularly polarized reconfigurable transmission units before and after rotation constitute two kinds of units in an orthogonal manner according to the arrangement direction of the diodes, the 1bit phase before rotation is 0° and 180°; the 1bit phase after rotation is 270° and 90°. The FPGA control board allocates different bias voltages to each 1bit circularly polarized reconfigurable transmission unit in the circularly polarized transmission surface, and controls the phases of the n×n 1bit circularly polarized reconfigurable transmission units independently, so that the reconfigurable transmission array antenna performs ±60° wide-angle beam scanning in a two-dimensional half space.

8. The reconfigurable transmitarray array antenna of claim 7, wherein, The circularly polarized planar feed array antenna is composed of 2×2 cut-corner square patches, and the energy is evenly divided to the four cut-corner square patches arranged in a rotation manner of 0°, 90°, 180° and 270° through a ring-shaped series feed network, so as to form a planar feed array antenna with wideband and 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 is covered with a super surface impedance matching layer composed of a plurality of small metal squares, so as to realize wide-angle impedance matching.

9. The reconfigurable transmitarray array antenna of claim 7, wherein, The FPGA control board is connected to the DC+ bias network concentrated on both sides of the transmission array antenna through 16 sockets on both sides; one socket on the left side controls two rows of n / 2 1bit super surface units on the left side of the corresponding row, and one socket on the right side controls two rows of n / 2 1bit super surface units on the right side of the corresponding row; the FPGA control board pre-stores the calculated beam phase code.

10. The reconfigurable transmissive array antenna of claim 7, wherein, The n is equal to 16, the circular polarization plane feed array radiates right-handed circularly polarized electromagnetic waves, the distance between the feed phase center and the transmission array is set to 100 mm, the focal ratio is 0.625, and each receiving patch of the transmission array is irradiated; the transmission array mirror reflects left-handed circularly polarized electromagnetic waves and receives right-handed circularly polarized electromagnetic waves, and controls the phase of each metasurface unit to re-radiate electromagnetic waves through the FPGA control board, and reconfigurable high-efficiency directional radiation is carried out on the transmission right-handed circularly polarized wave.

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