1-bit circularly polarized reconfigurable transmissive unit and reconfigurable transmissive array antenna

Abstract

The application provides a 1bit circular polarization reconfigurable transmission unit, belongs to the field of low-orbit satellite communication, and comprises, from top to bottom, a radiation patch, a first dielectric substrate, a ground plate, a second dielectric substrate, a bias circuit, a third dielectric substrate and a receiving patch. The radiation patch is single-sidedly slotted and connected to a first capacitor disc at the center of the ground plate through a metallized through hole at the center of the first dielectric substrate; the inner patch of the receiving patch is connected to a second capacitor disc through a metallized through hole at the center of the third dielectric substrate; the second capacitor disc is located on the third dielectric substrate and connected to the bias circuit; the outer patch of the receiving patch is connected to the bias circuit through a metallized through hole; and the inner patch and the outer patch are bridged through two PIN diodes with consistent orientations; and the application further provides an array antenna. The capacitor disc coupling replaces the metallized through hole, greatly reduces the complexity and cost, the radiation patch is single-sidedly slotted to break the structural symmetry, the conversion efficiency of linear polarization waves is improved when the array is formed, and the circular polarization performance is improved.

Description

Technical Field

[0001] This invention relates to the field of low-Earth orbit satellite communication technology, and in particular to a 1-bit circularly polarized reconfigurable transmission element and a reconfigurable transmission array antenna. Background Technology

[0002] Transmissive array antennas, as air-fed antennas, have broad application prospects in low-Earth orbit (LEO) satellite communication terminal equipment due to their advantages such as low cost, ease of fabrication, and simple beam control logic. However, with the increasing demands of LEO satellite communication for high dynamic scanning speed, strong interference resistance, and miniaturized integration, traditional transmissive array antennas are gradually revealing several performance bottlenecks. (1) Insufficient circular polarization performance. Most designs have problems such as narrow axial ratio bandwidth and low polarization purity, making it difficult to resist interference in complex electromagnetic environments and failing to meet the stability requirements of satellite communication links; (2) Unreasonable array structure design. Traditional multilayer dielectric substrates often use metallized vias to achieve interlayer connections, which not only leads to a higher array profile and larger volume, but also increases processing complexity and manufacturing costs, which is not conducive to the miniaturization and integration of terminal equipment; (3) Low bit number reconfigurable transmission arrays are prone to problems such as increased cross-polarization level and deterioration of side lobes when implementing beam scanning, which seriously affects communication quality; (4) Insufficient integration of phase modulation technology. Although geometric phase technology can achieve high-precision phase control, existing applications are mostly limited to fixed beam design and lack effective integration with reconfigurable technology, making it difficult to optimize polarization performance and beam scanning performance at the same time.

[0003] In existing technologies, solutions to improve circular polarization performance often rely on complex unit structure improvements or multi-port feed network designs, which not only increase design difficulty but may also introduce additional signal loss. Attempts to reduce array size and manufacturing costs often come at the cost of sacrificing beam scanning angle, gain stability, or axial ratio bandwidth. Furthermore, most reconfigurable transmission arrays employ only a single phase modulation technique, making it difficult to simultaneously meet the combined requirements of wide bandwidth, large-angle scanning, and high polarization purity, thus failing to fully satisfy the practical application scenarios of low-Earth orbit satellite communication. For example, Chinese invention patent application CN110911831A, "A Dual-Frequency Circularly Polarized Planar Transmission Array Antenna Using a Single-Linear Polarized Feed," includes a linearly polarized feed and a transmission array. Circular polarization radiation is achieved by phase compensation in both high-frequency and low-frequency units, with the transmitting patch rotating within each unit. The high-frequency unit consists of a high-frequency transmitting patch passing through a metal through-hole through a metal ground plane and a high-frequency receiving patch, while the low-frequency unit consists of a low-frequency transmitting patch passing through a metal through-hole through a metal ground plane and a low-frequency receiving patch. There are two problems with this transmission array antenna: First, the high-frequency and low-frequency elements are connected by metallized vias, which not only results in a higher array profile and larger volume, but also increases the processing complexity and manufacturing cost, which is not conducive to the miniaturization and integration of terminal equipment. Second, the working principle of this transmission array antenna to achieve circular polarization radiation is as follows: the linearly polarized feed illuminates the transmission array, and the signal radiated from each high-frequency or low-frequency element is a linearly polarized signal, which is then circularly polarized by the entire transmission array, resulting in a significant reduction in signal utilization.

[0004] Therefore, developing a reconfigurable transmission array antenna that combines axial ratio bandwidth, large-angle beam scanning, high polarization purity, and low cost has become a key technological requirement in the field of satellite communications. Summary of the Invention

[0005] The technical problem to be solved by this invention is: how to solve the problems of insufficient circular polarization performance, large array size and high manufacturing cost of traditional transmission array antennas in low-orbit satellite communication applications.

[0006] The present invention solves the above-mentioned technical problems through the following technical solution: a 1-bit circularly polarized reconfigurable transmission unit, comprising, from top to bottom, a radiating patch, a first dielectric substrate, a ground plane, a second dielectric substrate, a bias circuit, a third dielectric substrate, and a receiving patch. The radiating patch has a slot on one side and is connected to a first capacitor disk at the center of the ground plane through a metallized through-hole in the center of the first dielectric substrate. The inner patch of the receiving patch is connected to a second capacitor disk through a metallized through-hole in the center of the third dielectric substrate. The second capacitor disk is located on the third dielectric substrate and connected to the bias circuit. The outer patch of the receiving patch is connected to the bias circuit through a metallized through-hole. The inner patch and the outer patch are bridged by two PIN diodes with the same orientation.

[0007] This invention's 1-bit circularly polarized reconfigurable transmission unit adopts a stacked structure of three-layer dielectric substrate and four-layer functional layer. Capacitor disk coupling replaces traditional metallized vias, significantly reducing the complexity and cost of multilayer board manufacturing. At the same time, the array structure is compact, which is conducive to the miniaturization and integration of satellite terminals. By slotting on one side of the radiating patch, the structural symmetry is broken, exciting two orthogonal modes with a 90-degree phase difference, thereby converting linearly polarized waves into right-hand circularly polarized waves and radiating them into free space. A single 1-bit circularly polarized reconfigurable transmission unit can achieve circularly polarized radiation. Compared with the existing technology where each antenna element in the array antenna converts linearly polarized waves into linearly polarized waves, and then the entire antenna array converts half of the linearly polarized waves into circularly polarized waves, the antenna array obtained by assembling the 1-bit circularly polarized reconfigurable transmission unit of this invention can greatly improve the conversion efficiency of linearly polarized waves, thereby improving the circular polarization performance of the antenna array.

[0008] Preferably, by controlling the on / off state of the two PIN diodes, the receiving patch receives the Y-polarized linearly polarized wave and completely reflects the X-polarized linearly polarized wave. After the Y-polarized linearly polarized wave is received, it is transmitted to the second capacitor disk through the metallized via in the center of the third dielectric substrate, then coupled to the first capacitor disk, and finally transmitted to the radiating patch through the metallized via in the center of the first dielectric substrate. The radiating patch converts the linearly polarized wave into a left-handed or right-handed circularly polarized wave and radiates it into free space.

[0009] Preferably, the radiating patch is rectangular, with a groove on one side and a rectangular groove inside the radiating patch.

[0010] Preferably, a circular groove is etched in the center of the ground plane, the first capacitor disk is printed in the circular groove, a groove is etched in the center of the upper surface of the third dielectric substrate, and the second capacitor disk is printed in the groove. The first capacitor disk and the second capacitor disk are coaxial.

[0011] Preferably, the bias circuit is located in the zero field direction of the receiving patch and includes a first bias line and a second bias line. One end of the first bias line is connected to the second capacitor disk, and one end of the second bias line is connected to the external patch through a metallized via. The other ends of the first bias line and the second bias line are respectively connected to the FPGA control board.

[0012] Preferably, the two PIN diodes are a first PIN diode and a second PIN diode, the anode of the first PIN diode is connected to the second extension of the outer surface mount, the cathode of the first PIN diode is connected to the first extension of the inner surface mount, the anode of the second PIN diode is connected to the first extension of the inner surface mount, and the cathode of the second PIN diode is connected to the second extension of the outer surface mount.

[0013] The present invention utilizes a bias network controlled by PIN diodes and FPGA to achieve rapid beam reconfiguration and fast beam switching, which can meet the requirements of low-Earth orbit satellite communication for dynamic scanning speed.

[0014] Preferably, the first and third dielectric substrates are both made of F4BME220 with a relative permittivity of 2.2 and a loss tangent of 0.0009; the second dielectric substrate is made of F4BTM350 with a relative permittivity of 3.55 and a loss tangent of 0.0027.

[0015] The present invention also provides a reconfigurable transmission array antenna, including a feed source, The 1-bit circularly polarized reconfigurable transmission unit is presented The array is arranged such that the feed emits Y-polarized linearly polarized waves, and each 1-bit circularly polarized reconfigurable transmission unit generates a circularly polarized wave. Each 1-bit circularly polarized reconfigurable transmission unit is then randomly rotated by an angle. Introducing geometric phase, The feed source is in the same direction as the feed source. The distance difference between the 1-bit circularly polarized reconfigurable transmission units generates an inherent transmission phase preset. By controlling the on / off state of the two PIN diodes, the 1-bit phase state of the 1-bit circularly polarized reconfigurable transmission unit is switched, thereby realizing beam scanning in a two-dimensional plane.

[0016] This invention, through composite phase pre-setting technology, achieves broadband two-dimensional beam scanning of a C-band circularly polarized transmission array for the first time, with a measured scanning angle of ±40°, covering the beam coverage requirements of low-Earth orbit satellite communication. It exhibits excellent circular polarization performance, with a 3dB axial ratio bandwidth fully covering the C-band downlink frequency band (3.6GHz~4.4GHz). The cross-polarization levels of all beam states are significantly lower than the main polarization level, resulting in high polarization purity and strong anti-interference capability. This solves the problems of increased cross-polarization levels and sidelobe deterioration in traditional transmission array antennas used in low-Earth orbit satellite communication applications. It also demonstrates good gain stability, with gain fluctuations within the operating frequency band ranging from 15.4dBic to 20.1dBic. The difference in main polarization gain among different beam states is less than 2.8dBic, resulting in stable radiation efficiency. Furthermore, the array sidelobe level is as low as -13dB, exhibiting high directivity and effectively reducing non-main directional radiation interference.

[0017] Preferably, the feed source is a rectangular waveguide horn antenna.

[0018] Preferably, the antenna also includes an FPGA control board, with the bias circuit of each 1-bit circularly polarized reconfigurable transmission unit connected to the FPGA control board. The FPGA control board assigns a different bias voltage to the bias circuit of each 1-bit circularly polarized reconfigurable transmission unit. Each 1-bit circularly polarized reconfigurable transmission element is used for phase-independent control, enabling fast beam switching and ±40-degree two-dimensional beam coverage of the reconfigurable transmission array antenna. Attached Figure Description

[0019] Figure 1 An exploded view of a 1-bit circularly polarized reconfigurable transmission unit provided in an embodiment of the present invention; Figure 2 A side view of a 1-bit circularly polarized reconfigurable transmission unit provided in an embodiment of the present invention; Figure 3 A top view of a 1-bit circularly polarized reconfigurable transmission unit provided in an embodiment of the present invention; Figure 4 A top view of another structure of the 1-bit circularly polarized reconfigurable transmission unit provided in an embodiment of the present invention; Figure 5 A top view of the bias circuit and receiving patch in a 1-bit circularly polarized reconfigurable transmission unit provided in an embodiment of the present invention; Figure 6 A bottom view of a 1-bit circularly polarized reconfigurable transmission unit provided in an embodiment of the present invention; Figure 7 A schematic diagram of a reconfigurable transmission array antenna provided in an embodiment of the present invention; Figure 8 This is a schematic diagram of the operation of a reconfigurable transmission array antenna provided in an embodiment of the present invention; Figure 9 Simulation results of gain and axial ratio as a function of frequency for the reconfigurable transmission array antenna provided in the embodiments of the present invention under beam states phi = 0 degrees, theta = ±10 degrees and ±20 degrees; Figure 10 Simulation results of gain and axial ratio as a function of frequency for the reconfigurable transmission array antenna provided in the embodiments of the present invention under beam states phi = 0 degrees, theta = ±30 degrees and ±40 degrees; Figure 11 Simulation results of gain and axial ratio as a function of frequency for the reconfigurable transmission array antenna provided in the embodiments of the present invention under beam states phi = 90 degrees, theta = ±10 degrees and ±20 degrees; Figure 12 Simulation results of gain and axial ratio as a function of frequency for the reconfigurable transmission array antenna provided in the embodiments of the present invention under beam states phi = 90 degrees, theta = ±30 degrees and ±40 degrees; Figure 13 The simulation results of the radiation pattern of the reconfigurable transmission array antenna at the center frequency point when phi = 0 degrees are provided in the embodiments of the present invention. Figure 14Simulation results of radiation patterns of all states of the reconfigurable transmission array antenna provided in the embodiments of the present invention at the center frequency when phi = 90 degrees; In the figure: 10 Radiation patch, 11 Slot, 12 Rectangular slot, 20 First dielectric substrate, 30 Ground plane, 40 Second dielectric substrate, 50 Bias circuit, 51 First bias line, 52 Second bias line, 60 Third dielectric substrate, 70 Receiving patch, 71 Internal patch, 711 First extension, 72 External patch, 721 Second extension, 81 First capacitor disk, 82 Second capacitor disk, 100 Feed source. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0021] like Figure 1 and Figure 2 As shown, this embodiment provides a 1-bit circularly polarized reconfigurable transmission unit, including a radiating patch 10, a first dielectric substrate 20, a ground plane 30, a second dielectric substrate 40, a bias circuit 50, a third dielectric substrate 60, and a receiving patch 70 arranged from top to bottom. The first dielectric substrate 20, ground plane 30, second dielectric substrate 40, and third dielectric substrate 60 are all rectangular, and the four rectangles can have the same size. When the four rectangles are stacked, their long sides and wide sides are parallel to each other. Figure 1 In the spatial coordinate system shown, the long side of the third dielectric substrate 60 is parallel to the x-axis, and the wide side of the third dielectric substrate 60 is parallel to the y-axis. The second dielectric substrate 40, the ground plane 30, and the first dielectric substrate 20 are stacked sequentially on the upper surface of the third dielectric substrate 60 along the positive z-axis. The first dielectric substrate 10 and the third dielectric substrate 60 are both 5 mm thick, made of F4BME220, with a relative permittivity of 2.2 and a loss tangent of 0.0009. The second dielectric substrate 40 is 0.25 mm thick, made of F4BTM350, with a relative permittivity of 3.55 and a loss tangent of 0.0027.

[0022] The radiating patch 10 has a slot on one side and is connected to the first capacitor disk 81 at the center of the ground plane 30 through a metallized through-hole in the center of the first dielectric substrate 20. The inner patch 71 of the receiving patch 70 is connected to the second capacitor disk 82 through a metallized through-hole in the center of the third dielectric substrate 60. The second capacitor disk 82 is located on the third dielectric substrate 60 and connected to the bias circuit 50. The outer patch 72 of the receiving patch 70 is connected to the bias circuit 50 through a metallized through-hole. The inner patch 71 and the outer patch 72 are bridged by two PIN diodes facing the same direction.

[0023] By controlling the on / off state of the two PIN diodes, the receiving patch 70 receives the Y-polarized linear wave and completely reflects the X-polarized linear wave. After the Y-polarized linear wave is received, it is transmitted to the second capacitor disk 82 through the metallized via in the center of the third dielectric substrate 60, and then coupled to the first capacitor disk 81. It is also transmitted to the radiating patch 10 through the metallized via in the center of the first dielectric substrate 20. The radiating patch 10 converts the linearly polarized wave into a left-handed or right-handed circularly polarized wave and radiates it into free space.

[0024] See Figure 3 The radiating patch 10 is rectangular and is disposed on the upper surface of the first dielectric substrate 20. The center of the radiating patch 10 does not coincide with the center of the first dielectric substrate 20, but the long side and the wide side of the radiating patch 10 are parallel to the long side and the wide side of the first dielectric substrate 20, respectively. Alternatively, the long side and the wide side of the radiating patch 10 can both be parallel to the long side and the wide side of the first dielectric substrate 20. A groove 11 is formed on one side of the radiating patch 10. The groove 11 is rectangular and has a length of L1 and a width of B1. A rectangular groove 12 is formed inside the radiating patch 10. The length of the rectangular groove 12 is L2 and the width is B2. The lengths L1 and L2 and the widths B1 and B2 can be set as needed. Traditional circularly polarized patch antennas require dual-port feeding, orthogonal patch stacking, or complex chamfer designs (such as double chamfers or oblique chamfers) to excite orthogonal degenerate modes, resulting in structural redundancy and susceptibility to signal interference. The radiating patch 10 of this invention employs an E-shaped structure of "single-sided rectangular slot + internal rectangular slot," breaking structural symmetry solely through a single-sided slot to excite two orthogonal modes, TM10 and TM01, naturally forming a 90° phase difference, directly converting linearly polarized waves into circularly polarized waves. This design eliminates the need for additional feeding networks or stacking structures; a single element can complete circularly polarized radiation, improving the linear-to-circular polarization conversion efficiency compared to the traditional scheme of "elemental linearly polarized radiation + array-synthesized circular polarization." It should be noted that... Figure 3 The radiating patch 10 shown can achieve right-hand circular polarization by... Figure 3 The mirrored setup of the radiation patch 10 shown can be obtained Figure 4The radiation patch shown, if... Figure 4 The radiating patch shown is arranged on the upper surface of the first dielectric substrate 20 and can achieve left-hand circular polarization.

[0025] A circular groove is etched in the center of the ground plane 30, and the first capacitor disk 81 is printed in the circular groove. A groove is etched in the center of the upper surface of the third dielectric substrate 60, and the second capacitor disk 82 is printed in the groove. The first capacitor disk 81 and the second capacitor disk 82 are coaxial. This invention transmits the incident linearly polarized wave to the radiating patch 10 through coupling of the first capacitor disk 81 and the second capacitor disk 82. In actual processing, only metallized vias need to be processed on the single-layer first dielectric substrate 20 and the third dielectric substrate 60, respectively. It is not necessary to stack the first dielectric substrate 20, the second dielectric substrate 40, and the third dielectric substrate 60 into multiple layers and then process the metallized vias. The capacitor disk coupling design of this invention transmits through coaxial non-contact coupling of "upper layer capacitor disk (ground plane side) + lower layer capacitor disk (bias circuit side)". There is no need to drill holes or adhesive layers on multi-layer substrates. Only capacitor disks and metallized vias need to be made separately during the processing of a single layer substrate. Signal transmission can be achieved by stacking and aligning them. While ensuring performance, manufacturing complexity and cost are reduced, which is beneficial to the miniaturization and integration of satellite terminals.

[0026] See Figure 5 The bias circuit 50 includes a first bias line 51 and a second bias line 52. One end of the first bias line 51 is connected to the second capacitor disk 82, and one end of the second bias line 52 is connected to an external surface mount device 72 through a metallized via. The other ends of the first bias line 51 and the second bias line 52 are respectively connected to the FPGA control board. See also Figure 6 The two PIN diodes are a first PIN diode and a second PIN diode, both of which are Skyworks SMP12760-079LF. The anode of the first PIN diode is connected to the second extension 721 of the external patch 72, and the cathode of the first PIN diode is connected to the first extension 711 of the internal patch 71. The anode of the second PIN diode is connected to the first extension 711 of the internal patch 71, and the cathode of the second PIN diode is connected to the second extension 721 of the external patch 72.

[0027] The control sequence code output by the FPGA control board applies a positive or negative level to the other end of the first bias line 51 and the second bias line 52, controlling the first and second PIN diodes so that one PIN diode is on and the other is off. For example, when the other end of the first bias line 51 is connected to a high level and the other end of the second bias line 52 is connected to a low level, the second PIN diode is on and the first PIN diode is off. When the other end of the first bias line 51 is connected to a low level and the other end of the second bias line 52 is connected to a high level, the first PIN diode is on and the second PIN diode is off. Using a single bias line design, the on / off state of the two PIN diodes is controlled by adjusting the positive and negative levels, thereby achieving the phase state switching between 0 degrees and 180 degrees for the 1-bit circularly polarized reconfigurable transmission unit, and thus realizing the electromagnetic equivalent rotation of the unit. The bias circuit 50 is applied in the zero-field direction of the receiving patch 70, which can reduce the impact on radiation performance.

[0028] See Figure 7 This embodiment A 1-bit circularly polarized reconfigurable transmission unit is presented The array arrangement enables a reconfigurable transmission array antenna. The feed 100 transmits Y-polarized linearly polarized waves. The feed 100 employs a rectangular waveguide horn antenna based on a modified standard rectangular waveguide BJ40, with a horn diameter of 100mm × 80mm and a height of 60mm. Its polarization direction is Y-polarized, consistent with the polarization of the receiving patch 70. Each 1-bit circularly polarized reconfigurable transmission element generates a circularly polarized wave. Each 1-bit circularly polarized reconfigurable transmission element is randomly rotated by an angle. Introducing geometric phase, See Figure 8 The feed 100 is in the same direction (e.g., the x-axis direction) as the feed source 100. The distance difference between each 1-bit circularly polarized reconfigurable transmission unit generates an inherent transmission phase preset. The bias circuit of each 1-bit circularly polarized reconfigurable transmission unit is connected to an FPGA control board. The FPGA control board assigns a different bias voltage to the bias circuit of each 1-bit circularly polarized reconfigurable transmission unit. By controlling the on / off state of two PIN diodes, the 1-bit phase state of the 1-bit circularly polarized reconfigurable transmission unit is switched. Each 1-bit circularly polarized reconfigurable transmission element is used for independent phase control, enabling rapid beam switching and ±40° two-dimensional beam coverage for the reconfigurable transmission array antenna. By combining geometric phase preset with inherent transmission phase preset, a composite phase preset technology is constructed, which enables precise beam control.

[0029] This invention is based on A 1-bit circularly polarized reconfigurable transmission unit is presented Taking the array arrangement as an example, we will perform simulation verification on the reconfigurable transmission array antenna. Figures 9 to 12 Simulation results of gain and axial ratio as a function of frequency show that, in two orthogonal planes, phi=0° (XOZ plane) and phi=90° (YOZ plane), when the beam points to the range of theta=-40°~40°, the gain of the reconfigurable transmission array antenna remains stable in the frequency band of 3.6~4.4GHz, and the gain fluctuation does not exceed 3dB at the full scan angle. Moreover, the performance of the beam states at the same angle in the two planes is highly consistent, with no obvious directional difference. In terms of axial ratio performance, the 3-dB axial ratio bandwidth of all beam states fully covers the frequency band of 3.6~4.4GHz, and the circular polarization purity is excellent. Figures 13 to 14 Simulation results of the center frequency radiation pattern show that within the ±40° beam coverage area of ​​the two-dimensional plane, the main lobe pointing perfectly matches the target angle, and the pointing accuracy meets the stringent requirements of low-Earth orbit satellite communication. The average cross-polarization voltage across all beam states is ≤-27dB, the cross-polarization ratio is ≥45dB, the sidelobe level is as low as -12.8dB, and there is no high-level sidelobe interference. Even at the maximum scanning angle, the main lobe shape remains regular, and no deterioration in cross-polarization occurs. These simulation results fully demonstrate that the array possesses excellent beam scanning capability, ultra-high polarization purity, and good directivity, and can comprehensively meet the core requirements of low-Earth orbit satellite communication for high dynamic scanning speed, strong anti-interference capability, and wide bandwidth coverage.

[0030] Working Principle: This invention designs a novel 1-bit circularly polarized reconfigurable transmission unit structure by stacking a three-layer dielectric substrate and four functional layers. The three dielectric substrates are a first dielectric substrate 20, a second dielectric substrate 40, and a third dielectric substrate 60. The four functional layers are a radiating patch 10, a ground plane 30, a bias circuit 50, and a receiving patch 70. Two PIN diodes with the same orientation are integrated on the receiving patch 70. Figure 3Taking the radiating patch and feed source emitting Y-polarized waves as an example, by controlling the on / off state of the two PIN diodes, the receiving patch 70 receives the Y-polarized waves and completely reflects the X-polarized waves. The reflection coefficient within the operating bandwidth is higher than -0.1dB. After the Y-polarized waves are received, they are transmitted to the second capacitor disk 82 through the metallized via in the center of the third dielectric substrate 60, then coupled to the first capacitor disk 81, and finally transmitted to the radiating patch 10 through the metallized via in the center of the first dielectric substrate 20. The radiating patch 10 has a slot on one side to break the structure. Symmetry is achieved by exciting two orthogonal modes with a 90-degree phase difference, thereby converting linearly polarized waves into right-hand circularly polarized waves and radiating them into free space. A single 1-bit circularly polarized reconfigurable transmission element can achieve circularly polarized radiation. Compared with the existing technology where each antenna element in the array converts linearly polarized waves into linearly polarized waves, and then the entire antenna array converts half of the linearly polarized waves into circularly polarized waves, the antenna array of this invention can greatly improve the conversion efficiency of linearly polarized waves, thereby improving the circular polarization performance of the antenna array. The reconfigurable transmission array antenna of this invention has a 3dB axial ratio bandwidth that completely covers the C-band downlink frequency band (3.6GHz~4.4GHz). The cross-polarization level of all beam states is significantly lower than the main polarization level, resulting in high polarization purity and strong anti-interference capability.

[0031] In the reconfigurable transmission array antenna obtained by assembling 1-bit circularly polarized reconfigurable transmission elements according to this invention, the present invention utilizes a composite phase pre-setting technology (CPPT) combining geometric phase pre-setting (GPP) and inherent transmission phase pre-setting (TPP). Based on the composite phase pre-setting technology and the circular polarization conversion mechanism of the 1-bit reconfigurable elements, beam control and polarization optimization are achieved. Geometric phase is introduced by rotating the E-shaped radiating patch. Different rotation angles correspond to different phase responses, and the rotation has minimal impact on the transmission coefficient, ensuring the accuracy and stability of phase control. Furthermore, the inherent transmission phase pre-setting generated by the difference in distance between each array element and the feed source forms a natural phase distribution. After combining the two, the 1-bit phase state (0° or 180°) of the unit is switched by the bias circuit controlled by the FPGA to achieve beam scanning in a two-dimensional plane. The received Y-polarized wave is coupled to the upper E-shaped radiating patch through a metallized via and the intermediate capacitor disk. The E-shaped radiating patch converts the linearly polarized wave into a right-hand circularly polarized wave and radiates it into free space. The transmission coefficient of this conversion process is higher than -1dB in the 3.73GHz~4.26GHz frequency band, and the minimum transmission loss is only 0.24dB (at 4GHz). The cross-polarized (left-hand circularly polarized) transmission coefficient is lower than -10dB, ensuring high polarization purity.

[0032] Furthermore, the bias circuit design simplifies phase switching control. Since the two PIN diodes are mounted in the same direction, a single bias line can control the switching between 0° and 180°. Combined with the control sequence code output by the FPGA, the array can achieve rapid beam switching and ±40° two-dimensional beam coverage, while ensuring high polarization purity, low cross-polarization level, and a compact structure. This reduces manufacturing difficulty and cost, meeting the requirements of low-Earth orbit satellite communication for high dynamic scanning speed, strong anti-interference capability, and miniaturized integration of terminal antennas. Simultaneously, the geometric phase preset technology effectively suppresses beam cross-polarization level. Combined with unit structure optimization and parameter adjustment, this ensures that the array maintains good polarization purity and gain stability across the entire scanning angle range. This invention achieves a good balance between scanning angle, bandwidth, polarization performance, and manufacturing cost, making it a low-cost, high-performance satellite communication terminal antenna solution that replaces traditional phased arrays.

[0033] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

A 1.1-bit circularly polarized reconfigurable transmission unit, characterized in that: The system comprises, from top to bottom, a radiating patch, a first dielectric substrate, a ground plane, a second dielectric substrate, a bias circuit, a third dielectric substrate, and a receiving patch. The radiating patch has a slot on one side and is connected to a first capacitor bank at the center of the ground plane via a metallized via in the center of the first dielectric substrate. The radiating patch is rectangular, with a slot on one side and a rectangular slot inside. The inner patch of the receiving patch is connected to a second capacitor bank via a metallized via in the center of the third dielectric substrate. The second capacitor bank is located on the third dielectric substrate and connected to the bias circuit. The ground plane has a circular slot in its center, and the first capacitor bank is located within this slot. The upper surface of the third dielectric substrate has a groove in its center, and the second capacitor bank is located within this groove. The first and second capacitor banks are coaxially coupled without contact. The outer patch of the receiving patch is connected to the bias circuit via a metallized via. The inner and outer patches are bridged by two PIN diodes facing the same direction.

2. The 1-bit circularly polarized reconfigurable transmission unit according to claim 1, characterized in that: By controlling the on / off state of the two PIN diodes, the receiving patch receives the Y-polarized linear wave and completely reflects the X-polarized linear wave. After the Y-polarized linear wave is received, it is transmitted to the second capacitor disk through the metallized via in the center of the third dielectric substrate, then coupled to the first capacitor disk, and finally transmitted to the radiating patch through the metallized via in the center of the first dielectric substrate. The radiating patch converts the linearly polarized wave into a left-handed or right-handed circularly polarized wave and radiates it into free space.

3. The 1-bit circularly polarized reconfigurable transmission unit according to claim 1, characterized in that: The bias circuit is located in the zero field direction of the receiving patch and includes a first bias line and a second bias line. One end of the first bias line is connected to the second capacitor disk, and one end of the second bias line is connected to the external patch through a metallized via. The other ends of the first bias line and the second bias line are respectively connected to the FPGA control board.

4. The 1-bit circularly polarized reconfigurable transmission unit according to claim 1, characterized in that: The two PIN diodes are a first PIN diode and a second PIN diode. The anode of the first PIN diode is connected to the second extension of the outer surface mount, and the cathode of the first PIN diode is connected to the first extension of the inner surface mount. The anode of the second PIN diode is connected to the first extension of the inner surface mount, and the cathode of the second PIN diode is connected to the second extension of the outer surface mount.

5. The 1-bit circularly polarized reconfigurable transmission unit according to claim 1, characterized in that: The first and third dielectric substrates are both made of F4BME220 with a relative permittivity of 2.2 and a loss tangent of 0.0009; the second dielectric substrate is made of F4BTM350 with a relative permittivity of 3.55 and a loss tangent of 0.0027.

6. A reconfigurable transmission array antenna, characterized in that: Including feed source, The 1-bit circularly polarized reconfigurable transmission unit according to any one of claims 1-5 is The array is arranged such that the feed emits Y-polarized linearly polarized waves, and each 1-bit circularly polarized reconfigurable transmission unit generates a circularly polarized wave. Each 1-bit circularly polarized reconfigurable transmission unit is then randomly rotated by an angle. Introducing geometric phase, The feed source is in the same direction as the feed source. The distance difference between the 1-bit circularly polarized reconfigurable transmission units generates an inherent transmission phase preset. By controlling the on / off state of the two PIN diodes, the 1-bit phase state of the 1-bit circularly polarized reconfigurable transmission unit is switched, thereby realizing beam scanning in a two-dimensional plane.

7. The reconfigurable transmission array antenna according to claim 6, characterized in that: The feed source is a rectangular waveguide horn antenna.

8. The reconfigurable transmission array antenna according to claim 6, characterized in that: The antenna also includes an FPGA control board. The bias circuit for each 1-bit circularly polarized reconfigurable transmission element is connected to the FPGA control board. The FPGA control board assigns a different bias voltage to the bias circuit of each 1-bit circularly polarized reconfigurable transmission element. Each 1-bit circularly polarized reconfigurable transmission element is used for phase-independent control, enabling fast beam switching and ±40-degree two-dimensional beam coverage of the reconfigurable transmission array antenna.

Images