A marine vehicle dual circular polarization MIMO communication system and method

Abstract

The application discloses a kind of waterborne vehicle double circular polarization MIMO communication system and method, belong to wireless communication technical field.System includes orthogonal double linear polarization antenna, 90 ° 3dB orthogonal hybrid electric bridge and microwave transceiver device;Two polarization ports of antenna are electrically connected with two coupling ports of electric bridge, and two synthesis ports of electric bridge receive sending device, realize linear polarization and the bidirectional conversion of circular polarization, constitute double circular polarization MIMO link.Antenna is placed on the stable platform containing azimuth axis, because transceiving circularly polarized wave does not need to roll compensation shaft, can add pitch axis.The application also provides method steps.The application suppresses water surface multipath fading, eliminates hull disturbance using circular polarization insensitive to roll, supplies chain with double linear polarization antenna, simplifies structure, reduces cost, and improves communication stability.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, specifically to a dual circular polarization MIMO communication system and method for watercraft, applicable to shipborne and shore-based wireless communication scenarios in aquatic environments such as sea, lakes, and rivers, and particularly suitable for high-speed MIMO communication scenarios that need to resist strong water surface reflections and ship roll disturbances. Background Technology

[0002] In the field of maritime wireless communication, especially in shipborne microwave MIMO communication systems, the stability of the communication link faces two major challenges: the strong specular reflection effect of the water surface (especially the sea surface) and the frequent rolling attitude disturbances of the ship. At the same time, the traditional system architecture has obvious defects, making it difficult to guarantee communication quality.

[0003] Existing technologies generally employ a "three-axis self-stabilizing platform + dual-polarized antenna" architecture. This architecture uses high-precision azimuth, pitch, and roll axis servo mechanisms to compensate for the ship's roll, pitch, and yaw in real time, attempting to maintain the absolute stability of the antenna beam pointing and polarization direction, thereby ensuring the orthogonality of MIMO communication. The dual-polarized antenna typically employs horizontal / vertical (H / V) polarization or ±45° polarization, and leveraging its mature supply chain advantages, it is widely used in various wireless communication systems.

[0004] However, the aforementioned existing technologies have fundamental flaws and cannot fundamentally solve the core pain points of maritime communication, as follows: First, mechanical compensation cannot resolve polarization distortion at the propagation level of electromagnetic waves. Water surfaces (especially sea surfaces) exhibit a strong specular reflection effect on electromagnetic waves. When a linearly polarized wave incident on the water surface, the polarization direction of the reflected wave undergoes a violent and random rotation, and the polarization direction of the reflected wave is no longer consistent with that of the direct wave. This polarization distortion is a physical phenomenon along the propagation path of the electromagnetic wave and is unrelated to the mechanical attitude of the transmitting antenna. Even if the antenna is stabilized in an absolutely horizontal state using the most precise three-axis platform, the receiver will still receive a reflected interference signal with a violently oscillating polarization direction, leading to the destruction of the orthogonality of the MIMO channel, a severe imbalance in the amplitude of the two signals, and a sharp decline in the quality of the communication link.

[0005] Second, there is a significant contradiction between system complexity and reliability. To cope with the high-frequency roll of the hull, existing solutions have to rely on high-cost, high-power three-axis electromechanical stabilization platforms. However, in actual aquatic environments, the high-frequency roll of the hull often exceeds the response bandwidth of the mechanical roll axis, resulting in compensation lag and failing to completely solve the polarization mismatch. At the same time, the three-axis platform has a complex mechanical structure and is large in size and weight. In the harsh environment of high humidity and high vibration on the water, the mechanical components are prone to wear and failure, resulting in high maintenance costs and seriously affecting the long-term stable operation of the system.

[0006] Third, the utilization rate of mature components is low. Dual-polarized antennas have a mature supply chain, low cost, and wide application, but traditional linear polarization schemes cannot cope with polarization distortion and roll disturbance problems in water scenarios, which prevents them from taking full advantage of their advantages and results in low utilization, further increasing the overall cost of the system.

[0007] Therefore, existing technologies are trapped in the dilemma of "trying to solve the physical problems of electromagnetic wave propagation with complex mechanical means", making it difficult to ensure high-speed and stable MIMO communication in the dual harsh environments of strong water surface reflection and violent shaking. There is an urgent need for a brand-new technical solution to solve the above pain points from the source, while taking into account communication stability, system simplification and cost controllability. Summary of the Invention Purpose of the invention

[0008] This invention aims to provide a dual-circular polarization MIMO communication system and method for watercraft, to solve the technical problems in the prior art caused by polarization distortion due to water surface reflection and polarization mismatch due to vehicle roll disturbance, resulting in poor communication quality, complex system structure, high cost and low reliability; at the same time, it reuses the mature dual-polarization antenna supply chain, lowers the threshold for implementation, and realizes high-speed, stable and low-cost MIMO communication for watercraft. Technical solution

[0009] To achieve the above-mentioned objectives, the present invention provides the following technical solution: a dual-circular polarization MIMO communication system for watercraft, comprising: an orthogonal dual-linear polarization antenna, a 90° 3dB orthogonal hybrid bridge, and a microwave communication transceiver; the two polarization output ports of the orthogonal dual-linear polarization antenna are electrically connected to the two coupling ports of the 90° 3dB orthogonal hybrid bridge in a one-to-one correspondence; the two combining ports of the 90° 3dB orthogonal hybrid bridge are both electrically connected to the microwave communication transceiver, for realizing bidirectional conversion between two orthogonal linear polarization signals and left-hand circular polarization signals and right-hand circular polarization signals, thereby forming a dual-circular polarization MIMO communication link.

[0010] Furthermore, the 90° 3dB orthogonal hybrid bridge is set independently or integrated into the microwave communication transceiver device and the orthogonal dual-polarized antenna module. The 90° 3dB orthogonal hybrid bridge is the core device for realizing bidirectional conversion between linear and circular polarized signals, and is used to provide orthogonal excitation with equal amplitude and 90° phase difference. The 90° 3dB orthogonal hybrid bridge covers all equivalent devices and device combinations that can realize the same 90° 3dB orthogonal hybrid function, that is, it can complete the bidirectional conversion between linear and circular polarized signals and provide orthogonal excitation with equal amplitude and 90° phase difference. Specifically, it includes, but is not limited to, the combination of a 3dB coupler and a 90° phase shifter, the combination of a power divider and a 90° phase shifting network, an active orthogonal phase processing module, and a microwave integrated orthogonal conversion chip.

[0011] Furthermore, the orthogonal dual-polarized antenna is an H / V dual-polarized antenna or a ±45° dual-polarized antenna, both of which are industry-standard components. Relying on a mature supply chain, the cost is controllable, the versatility is strong, and existing components can be directly reused without the need for custom-designed antennas.

[0012] Furthermore, the orthogonal dual-polarized antenna is mounted on a stable platform; the stable platform includes an azimuth axis, and because the antenna transmits and receives dual circularly polarized waves, there is no need to set a roll compensation axis; the stable platform also includes an optional pitch axis, and the pitch axis does not have a roll compensation function.

[0013] Furthermore, the system also includes a second orthogonal dual-polarized antenna and a second 90° 3dB orthogonal hybrid bridge; the two orthogonal dual-polarized antennas and the two 90° 3dB orthogonal hybrid bridges correspond one-to-one, each independently completing the conversion of linear polarized signals to circular polarized signals, forming two independent left-hand circular polarized and right-hand circular polarized MIMO channels.

[0014] Furthermore, the two orthogonal dual-polarized antennas are electrically connected to the two 90° 3dB orthogonal hybrid bridges using a cross-polarization combination. Specifically, if it is an H / V dual-polarized antenna, the H port of the first antenna and the V port of the second antenna are electrically connected to the same coupling port of the 90° 3dB orthogonal hybrid bridge, and the V port of the first antenna and the H port of the second antenna are electrically connected to the coupling port of another 90° 3dB orthogonal hybrid bridge. If it is a ±45° dual-polarized antenna, the +45° port of the first antenna and the -45° port of the second antenna are electrically connected to the same coupling port of the 90° 3dB orthogonal hybrid bridge, and the -45° port of the first antenna and the +45° port of the second antenna are electrically connected to the coupling port of another 90° 3dB orthogonal hybrid bridge.

[0015] Furthermore, in the transmitting state, the 90° 3dB orthogonal hybrid bridge converts the two MIMO signals output by the microwave communication transceiver into orthogonal linearly polarized signals with equal amplitude and a phase difference of ±90°, which are then radiated by the orthogonal dual-linear polarized antenna to form left-hand and right-hand orthogonal circularly polarized waves. In the receiving state, the orthogonal dual-linear polarized antenna receives the spatial circularly polarized wave, which is decomposed and restored into two independent MIMO signals by the 90° 3dB orthogonal hybrid bridge and sent to the microwave communication transceiver for processing.

[0016] This invention also provides a dual circular polarization MIMO communication method for watercraft, applied to any of the above-described dual circular polarization MIMO communication systems for watercraft, comprising the following steps: S1. Connect the two polarization output ports of the orthogonal dual-polarized antenna to the two coupling ports of the 90° 3dB orthogonal hybrid bridge in a one-to-one correspondence; the orthogonal dual-polarized antenna is an H / V dual-polarized antenna or a ±45° dual-polarized antenna; the 90° 3dB orthogonal hybrid bridge is set independently or integrated internally, and it is selected from equivalent devices that can realize equal amplitude, 90° phase difference orthogonal excitation; S2. Connect the two combined ports of the 90° 3dB orthogonal hybrid bridge to the MIMO port of the microwave communication transceiver to construct a dual circular polarization MIMO communication link; S3. In the transmit state, the 90° 3dB orthogonal hybrid bridge converts the two MIMO signals into orthogonal linearly polarized signals with equal amplitude and a phase difference of ±90°, which are then radiated by the orthogonal dual-linear polarized antenna as either a left-hand circularly polarized wave or a right-hand circularly polarized wave. In the receive state, the orthogonal dual-linear polarized antenna receives the spatial circularly polarized wave, which is then decomposed and restored by the 90° 3dB orthogonal hybrid bridge into two independent MIMO signals, which are then sent to the microwave communication transceiver for processing.

[0017] Furthermore, the method also includes a second orthogonal dual-polarized antenna and a second 90° 3dB orthogonal hybrid bridge; the two orthogonal dual-polarized antennas and the two 90° 3dB orthogonal hybrid bridges correspond one-to-one and operate independently to achieve independent radiation of left-hand circularly polarized waves and right-hand circularly polarized waves, respectively.

[0018] Furthermore, the method also includes a second orthogonal dual-polarized antenna and a second 90° 3dB orthogonal hybrid bridge; the two orthogonal dual-polarized antennas and the two 90° 3dB orthogonal hybrid bridges are electrically connected in a linear polarization cross combination manner to optimize port isolation.

[0019] The dual-circular polarization MIMO signal utilizes the physical characteristic of reversing rotation after reflection (left-handed circularly polarized waves mainly become right-handed circularly polarized waves after reflection, and vice versa), ensuring that the direct and reflected waves are naturally orthogonal in the polarization domain. This prevents the reflected signal from superimposing with the direct signal to form fading interference, effectively suppressing multipath fading caused by strong water surface reflection. Simultaneously, by utilizing the insensitivity of circularly polarized waves to roll attitude, it eliminates polarization mismatch caused by hull roll disturbances, ensuring the stability of the communication link and the continuity of high-speed communication under the swaying conditions of the watercraft. The above is a detailed explanation of the technical principles and beneficial effects utilized in this invention.

[0020] Beneficial effects

[0021] Compared with the prior art, the present invention has the following significant advantages: Suppressing water surface reflection fading from the electromagnetic source: This invention utilizes the physical characteristic that the rotation direction of circularly polarized waves reverses after reflection on the water surface. By constructing a dual-circularly polarized MIMO system through an orthogonal dual-linearly polarized antenna and a 90° 3dB orthogonal hybrid bridge, the direct wave and the reflected wave are naturally orthogonal in the polarization domain. The reflected signals no longer superimpose as fading interference, thus fundamentally solving the technical problem of deep fading caused by the violent rotation of polarization direction and the superposition of direct and reflected signals in the existing linear polarization scheme under strong water surface reflection environment, and greatly improving the link's anti-interference capability; Eliminating the impact of roll attitude from the physical characteristics of polarization: This invention utilizes the inherent characteristic that circularly polarized waves are insensitive to roll (rotation around the antenna axis) attitude, so that the orthogonal dual-polarized antenna system does not need to set a roll compensation axis. Unlike the existing technology, which must rely on a three-axis platform (including a roll axis) to compensate for polarization mismatch caused by hull rolling, this invention completely eliminates the impact of roll disturbance on communication through the properties of electromagnetic waves themselves, realizing "electromagnetic cure instead of mechanical compensation", solving the polarization mismatch problem from the source; Achieving fundamental simplification of system architecture and reducing cost and failure rate: Based on the above two points, this invention simplifies the reliance of traditional shipborne communication systems on "high-precision three-axis electromechanical stabilization platforms" to only requiring beam alignment on the azimuth axis (or azimuth + pitch axis). This not only significantly reduces the system's size, weight, power consumption and manufacturing cost, but also reduces mechanical failure points, avoids communication interruptions caused by mechanical roll axis response lag or failure, and improves system reliability in harsh maritime environments. Reusing a mature supply chain, low barriers to entry and high cost performance: This invention directly reuses the existing mature dual-polarized antenna supply chain (H / V and ±45° dual-polarized antennas are common components in the industry), without the need to customize dedicated circular polarized antennas, which greatly reduces component costs and R&D cycle; the 90° 3dB bridge and equivalent components can be set up independently or integrated, adapting to different equipment architectures, with low barriers to entry and easy large-scale promotion and application. Ensuring MIMO channel stability: The left and right circularly polarized waves have highly symmetrical fading characteristics on the propagation path, which enables the MIMO channel matrix to maintain good orthogonality and condition number over a long period of time. This ensures the stable maintenance of the spatial multiplexing gain of the MIMO system, guarantees continuous communication stability, and adapts to the communication needs of various watercraft. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1This is a schematic diagram of the structure of the dual circular polarization MIMO communication system for watercraft in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram illustrating the connection and signal conversion between the orthogonal dual-polarized antenna and the 90° 3dB orthogonal hybrid bridge in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the independent dual-antenna scheme in Embodiment 2 of the present invention; Figure 4 This is a connection diagram of the dual-antenna cross combination scheme in Embodiment 3 of the present invention; Figure 5 This is a schematic diagram of the waterborne communication scenario in which the present invention is applied.

[0024] The markings and descriptions of each component in the diagram are as follows: 11- The first orthogonal dual-polarized antenna, one of the orthogonal dual-polarized antennas, is used to construct a MIMO channel; 12- The second orthogonal dual-polarized antenna is another orthogonal dual-polarized antenna, which is set independently from the first orthogonal dual-polarized antenna and is used to construct a MIMO channel; 21-The first 90° 3dB orthogonal hybrid bridge, independently set or built-in integrated, is electrically connected to the first orthogonal dual-polarized antenna to realize bidirectional conversion between linear polarized signals and circular polarized signals; 22 - The second 90° 3dB orthogonal hybrid bridge, either independently set or built-in integrated, is electrically connected to the second orthogonal dual-polarized antenna to realize bidirectional conversion between linearly polarized and circularly polarized signals; 3-Microwave communication transceiver, used to realize the transmission and reception processing of MIMO signals; 4-Stabilized platform, used to mount the antenna and achieve azimuth pointing adjustment, which includes an azimuth axis, and can optionally add a pitch axis, but does not have a roll compensation axis; 5-Water vehicle, which serves as the application carrier for this invention; 6-Water surface, serving as a reflective medium in communication scenarios; First coupling port A, second coupling port A, first coupling port B, and second coupling port B are the ports for connecting the first and second 90° 3dB orthogonal hybrid bridges to the corresponding antennas, respectively. First synthesis port C, first synthesis port D, second synthesis port C, and second synthesis port D are all ports for connecting the first and second 90° 3dB orthogonal hybrid bridges to the microwave communication transceiver. The first horizontal H / +45° polarization port, the second horizontal H / +45° polarization port, the first vertical V / -45° polarization port, and the second vertical V / -45° polarization port are the corresponding polarization ports of the two orthogonal dual-line polarized antennas. The first horizontal H / +45° dipole, the second horizontal H / +45° dipole, the first vertical V / -45° dipole, and the second vertical V / -45° dipole correspond to the polarization dipoles of two orthogonal dual-polarized antennas, respectively. The first 90° phase-shifting network, corresponding to the first 90° 3dB quadrature hybrid bridge, is used to realize 90° phase-shifting processing of the signal; The second 90° phase-shifting network, corresponding to the second 90° 3dB quadrature hybrid bridge, is used to realize 90° phase-shifting processing of the signal; RF1 and RF2 are MIMO radio frequency ports for microwave communication transceivers; Axis configuration for a stable platform: single horizontal axis / dual horizontal pitch axis / no roll axis required; Shore-based / other waterborne vehicles serve as the communication carriers for the other end in a communication scenario. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1: Single Antenna Scheme

[0026] like Figure 1 , Figure 2 As shown, this embodiment provides a dual circular polarization MIMO communication system for watercraft. The system includes: a first orthogonal dual-polarized antenna 11, a first 90° 3dB orthogonal hybrid bridge 21, and a microwave communication transceiver 3. It can be adapted to the communication needs of various watercraft. Its core features are the simplest structure and controllable cost. It achieves dual circular polarization MIMO communication by relying on the combination of a single antenna and a single bridge.

[0027] The first orthogonal dual-polarized antenna 11 adopts a dual-adaptive-port design. Its two polarization ports are defined as a first horizontal H / +45° polarization port and a first vertical V / -45° polarization port, which is compatible with both H / V dual-polarized antennas and ±45° dual-polarized antennas. No structural modifications to the antenna are required, and existing mature supply chains can be directly reused. The antenna is mounted on a stabilization platform 4, which includes an azimuth axis. Because the antenna transmits and receives dual circularly polarized waves, a roll compensation axis is not required. The stabilization platform also includes an optional elevation axis, which does not have roll compensation functionality, ensuring communication accuracy while avoiding mechanical structural complexity.

[0028] The first horizontal H / +45° polarization port and the first vertical V / -45° polarization port of the first orthogonal dual-polarized antenna 11 are electrically connected one-to-one with the first coupling port A and the first coupling port B of the first 90° 3dB orthogonal hybrid bridge 21, respectively. The specific adaptation rules for the dual-adapter ports are as follows: when using an H / V dual-polarized antenna, the two ports are used as the horizontal H polarization port and the vertical V polarization port, respectively; when using a ±45° dual-polarized antenna, the two ports are used as the +45° polarization port and the -45° polarization port, respectively, without changing the port wiring and bridge parameters. The first 90° 3dB orthogonal hybrid bridge 21 encompasses all equivalent devices and device combinations capable of achieving the same 90° 3dB orthogonal hybrid function, i.e., capable of bidirectional conversion between linear and circular polarization signals and providing equal amplitude and 90° phase difference orthogonal excitation; specifically including but not limited to combinations of 3dB couplers and 90° phase shifters, combinations of power dividers and 90° phase shifting networks, active orthogonal phase processing modules, and microwave integrated orthogonal conversion chips. It can be set independently or integrated into the microwave communication transceiver device 3 or antenna module. It has a built-in 90° phase shifting network, and the first synthesis port C and the first synthesis port D are electrically connected to the RF1 and RF2 ports of the microwave communication transceiver device 3, respectively, to form a complete dual circular polarization MIMO communication link, realizing bidirectional conversion between linear and circular polarization signals.

[0029] The signal transmission and reception process in this embodiment is as follows, realizing bidirectional conversion between linearly polarized and circularly polarized signals to complete dual-circularly polarized MIMO communication: Transmission mode: The microwave communication transceiver 3 upconverts two independent MIMO baseband signals to radio frequency, and sends them to the first synthesis port C and the first synthesis port D of the first 90° 3dB orthogonal hybrid bridge 21 through RF1 and RF2 ports respectively; the bridge performs 90° phase shift and power distribution on the two radio frequency signals through the built-in phase shift network, and outputs orthogonal linear polarized signals with equal amplitude and a phase difference of ±90° at the first coupling ports A and B, respectively, which are fed into the dual adapter ports of the first orthogonal dual-linear polarized antenna 11; the signal radiation is completed according to the selected antenna type, and finally left-hand circularly polarized wave and right-hand circularly polarized wave are formed to realize the stable transmission of dual-circularly polarized MIMO signal; Reception mode: The first orthogonal dual-polarized antenna 11 receives left-handed and right-handed circularly polarized waves in space through dual adapter ports, converts them into corresponding orthogonal linearly polarized signals, and sends them to the coupling ports A and B of the first 90° 3dB orthogonal hybrid bridge 21; the bridge performs orthogonal mixing and power synthesis on the two linearly polarized signals, decomposes and restores them into two independent MIMO radio frequency signals, and sends them to the microwave communication transceiver 3 through the first synthesis port C and the first synthesis port D. After down-conversion and baseband processing, the signal reception is completed. The receiving link and the transmitting link are completely symmetrical, ensuring the consistency and stability of communication.

[0030] The advantages of this embodiment match the system design: the dual-adapter port of the antenna is compatible with two general dual-polarized antennas, reusing existing mature supply chains, which greatly reduces the cost of components and the threshold for implementation; the stabilization platform eliminates the roll compensation axis design, relying on the inherent characteristic of circularly polarized waves being insensitive to roll attitude, eliminating the influence of hull roll disturbances from the electromagnetic level, simplifying the mechanical structure, reducing power consumption and maintenance costs; the combination architecture of a single antenna and a single bridge is the simplest, which can effectively resist water surface reflection and hull roll disturbances, taking into account both communication stability and cost controllability, and can be widely adapted to the basic communication needs of various watercraft. Example 2: Independent Dual-Antenna Scheme

[0031] like Figure 3 As shown, this embodiment provides a dual circular polarization MIMO communication system for watercraft. Based on the first embodiment, the architecture is optimized. The system includes: two orthogonal dual-polarized antennas (first orthogonal dual-polarized antenna 11, second orthogonal dual-polarized antenna 12), two 90° 3dB orthogonal hybrid bridges (first bridge 21, second bridge 22), and microwave communication transceiver 3. Through the one-to-one correspondence between the dual antennas and the dual bridges, the radiation of left-hand circularly polarized waves and right-hand circularly polarized waves is separated and implemented independently by the two antennas.

[0032] The first and second orthogonal dual-polarized antennas 11 and 12 both adopt the same dual-adaptive port design as in Embodiment 1. The ports are defined as a horizontal H / +45° polarization port and a vertical V / -45° polarization port, which are compatible with both H / V dual-polarization and ±45° dual-polarization antennas. No structural modification is required, and existing components can be directly reused. Both antennas are mounted on a stabilization platform 4, which includes an azimuth axis. Because the antennas transmit and receive dual circularly polarized waves, no roll compensation axis is required. The stabilization platform also includes an optional pitch axis, which does not have roll compensation functionality. This ensures communication accuracy while avoiding mechanical structural complexity, adapting to the installation requirements of various watercraft.

[0033] The first orthogonal dual-polarized antenna 11 is connected to the first 90° 3dB orthogonal hybrid bridge 21, and the second orthogonal dual-polarized antenna 12 is connected to the second 90° 3dB orthogonal hybrid bridge 22. The two sets of combinations work independently and do not interfere with each other, respectively completing the bidirectional conversion from linearly polarized signals to circularly polarized signals. The type selection of the two bridges is completely consistent with that in Embodiment 1, covering all equivalent devices and device combinations that can achieve the same 90° 3dB orthogonal hybrid function. They can be set independently or integrated into the microwave communication transceiver device 3, flexibly adapting to different installation space requirements. The built-in 90° phase shifting network is used to realize the bidirectional conversion between linearly polarized and circularly polarized signals.

[0034] The port connection logic is as follows: the dual adapter ports of the first orthogonal dual-polarized antenna 11 are electrically connected to the coupling ports A and B of the first 90° 3dB orthogonal hybrid bridge 21 respectively; the dual adapter ports of the second orthogonal dual-polarized antenna 12 are electrically connected to the coupling ports A and B of the second 90° 3dB orthogonal hybrid bridge 22 respectively. The adaptation rules of the dual adapter ports are completely consistent with those of Embodiment 1, and there is no need to change the wiring and bridge parameters. To form two independent dual-circular polarization MIMO channels, the first synthesizing port C of the first 90° 3dB orthogonal hybrid bridge 21 is connected to the RF1 port of the microwave communication transceiver 3, and its first synthesizing port D is connected to a 50Ω load; the second synthesizing port D of the second 90° 3dB orthogonal hybrid bridge 22 is connected to the RF2 port of the microwave communication transceiver 3, and its second synthesizing port C is connected to a 50Ω load, thereby achieving physical decoupling of the left-hand and right-hand circular polarization generation paths, so as to realize the independent radiation of the left-hand circular polarization wave and the right-hand circular polarization wave respectively.

[0035] The working principle of this embodiment is exactly the same as that of Embodiment 1. The core difference lies in the adoption of a one-to-one independent architecture of "two antennas + two bridges" to physically decouple the generation paths of left-hand and right-hand circular polarization. The advantages of this architecture are: it can reuse existing general-purpose antennas and bridge devices, relax the performance requirements of a single 90° 3dB orthogonal hybrid bridge, and lower the threshold for device selection; the dual independent link design improves the redundancy and reliability of the system. Even if one link fails, the other link can still maintain basic communication, making it suitable for various watercraft scenarios with high requirements for communication reliability. Example 3: Dual-antenna cross combination scheme

[0036] like Figure 4 As shown, this embodiment provides a dual circular polarization MIMO communication system for watercraft. The system configuration is completely consistent with that of Embodiment 2, including a first orthogonal dual-polarized antenna 11, a second orthogonal dual-polarized antenna 12, a first 90° 3dB orthogonal hybrid bridge 21, a second 90° 3dB orthogonal hybrid bridge 22, and a microwave communication transceiver device 3. The core improvement is that the two orthogonal dual-polarized antennas and the two 90° 3dB orthogonal hybrid bridges are electrically connected in a linear polarization cross combination to optimize port isolation.

[0037] The system configuration, component selection, and stable platform design in this embodiment are completely consistent with those in Embodiment 2. The two orthogonal dual-polarized antennas still employ the same dual-adaptor port design as in Embodiments 1 and 2, compatible with both H / V dual-polarization and ±45° dual-polarization antennas. The adaptation rules remain consistent with the previous two embodiments, requiring no changes to wiring or bridge parameters. The core difference in this embodiment lies solely in the port connection method between the two antennas and the two bridges: a linear polarization cross combination. The specific connection logic is as follows: If it is an H / V dual-polarized antenna, the H port of the first antenna and the V port of the second antenna are electrically connected to the same coupling port of the 90° 3dB orthogonal hybrid bridge, and the V port of the first antenna and the H port of the second antenna are electrically connected to another coupling port of the 90° 3dB orthogonal hybrid bridge. If it is a ±45° dual-polarized antenna, the +45° port of the first antenna and the -45° port of the second antenna are electrically connected to the same coupling port of the 90° 3dB orthogonal hybrid bridge, and the -45° port of the first antenna and the +45° port of the second antenna are electrically connected to another coupling port of the 90° 3dB orthogonal hybrid bridge.

[0038] This cross-connection method improves signal isolation between ports without changing the bidirectional conversion function between linear and circular polarization signals.

[0039] The connection method and function of the bridge to the microwave communication transceiver 3 in this embodiment are completely consistent with those in Embodiment 2: the first synthesizing port C of the first 90° 3dB orthogonal hybrid bridge 21 is connected to the RF1 port of the microwave communication transceiver 3, and the first synthesizing port D is connected to a 50Ω load; the second synthesizing port D of the second 90° 3dB orthogonal hybrid bridge 22 is connected to the RF2 port of the microwave communication transceiver 3, and the second synthesizing port C is connected to a 50Ω load, ensuring the formation of two independent dual circular polarization MIMO channels. The bidirectional conversion principle of linear polarization and circular polarization signals and the signal transmission and reception process are completely consistent with those in Embodiments 1 and 2.

[0040] The advantages of this embodiment are achieved based on the cross-connection architecture: the port cross-combination design significantly improves the signal isolation between ports of the MIMO system, effectively suppresses crosstalk and external interference between ports, thereby increasing the system input power and enhancing the coverage of the communication link; the dual-adapter antenna ports can reuse existing general-purpose components, reducing costs and implementation barriers, an advantage consistent with embodiments one and two; the stabilization platform eliminates the roll compensation axis, relying on the inherent characteristic of circularly polarized waves being insensitive to roll attitude to ensure communication stability during hull swaying, which is completely consistent with the stabilization platform design logic and core function of the previous two embodiments. The overall architecture takes into account communication quality, reliability, and cost controllability, and can be adapted to various watercraft scenarios with high requirements for communication isolation. Application Scenario Description

[0041] like Figure 5As shown, this invention can be widely applied to various waterborne communication scenarios, including but not limited to: ship-to-ship communication, ship-to-shore communication, shore-to-shore communication, and wireless broadband access in waterways such as lakes, rivers, and ports. A stabilization platform 4 is installed on the waterborne vehicle 5. The stabilization platform 4 includes an azimuth axis, and because the antenna transmits and receives dual circularly polarized waves, a roll compensation axis is not required; a pitch axis can be selectively added. The stabilization platform 4 carries an orthogonal dual-polarized antenna 1, which is signal-connected to a 90° 3dB orthogonal hybrid bridge 2. The 90° 3dB orthogonal hybrid bridge 2 is signal-connected to a microwave communication transceiver 3, completing signal transmission and processing. The reflected waves generated by the water surface 6 and the direct waves transmitted by the shore-based / other waterborne vehicles are received by the orthogonal dual-polarized antenna 1 and then polarized through the 90° 3dB orthogonal hybrid bridge 2, ensuring stable communication.

[0042] This invention does not limit the communication distance, antenna height, or elevation angle, and is applicable to various microwave communication systems using MIMO technology. It can be adapted to various watercraft such as small speedboats, medium-sized cargo ships, and large cruise ships, and has broad application prospects.

[0043] In summary, this invention, by introducing a 90° 3dB orthogonal hybrid bridge, transforms a general-purpose dual-linear polarized antenna into a dual-circular polarized MIMO antenna. It fully utilizes the physical characteristics of circularly polarized waves, solving the communication pain points caused by water surface reflection and ship roll disturbances from the electromagnetic source. At the same time, it reuses mature component supply chains, simplifies the system structure, reduces costs and implementation barriers, and achieves a balance between communication stability, system simplification, and cost controllability for waterborne vehicles. It has significant technological advancements and practical value.

[0044] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A dual-circular polarization MIMO communication system for watercraft, characterized in that, include: Orthogonal dual-polarized antenna, 90° 3dB orthogonal hybrid bridge, and microwave communication transceiver; The two polarization output ports of the orthogonal dual-linear polarization antenna are electrically connected one-to-one with the two coupling ports of the 90° 3dB orthogonal hybrid bridge; the two combining ports of the 90° 3dB orthogonal hybrid bridge are electrically connected to the microwave communication transceiver device to realize bidirectional conversion between the two orthogonal linear polarization signals and the left-hand circular polarization signal and the right-hand circular polarization signal, thus forming a dual-circular polarization MIMO communication link.

2. The dual circular polarization MIMO communication system for watercraft according to claim 1, characterized in that, The 90° 3dB orthogonal hybrid bridge is set independently or integrated into the microwave communication transceiver device and the orthogonal dual-linear polarized antenna module. The 90° 3dB orthogonal hybrid bridge is the core device for realizing bidirectional conversion between linear and circular polarized signals, and is used to provide orthogonal excitation with equal amplitude and 90° phase difference. The 90° 3dB orthogonal hybrid bridge covers all equivalent devices and device combinations that can realize the same 90° 3dB orthogonal hybrid function, that is, it can complete the bidirectional conversion between linear and circular polarized signals and provide orthogonal excitation with equal amplitude and 90° phase difference. Specifically, it includes, but is not limited to, the combination of a 3dB coupler and a 90° phase shifter, the combination of a power divider and a 90° phase shifting network, an active orthogonal phase processing module, and a microwave integrated orthogonal conversion chip.

3. The dual circular polarization MIMO communication system for watercraft according to claim 1, characterized in that, The orthogonal dual-polarized antenna is an H / V dual-polarized antenna or a ±45° dual-polarized antenna.

4. The dual circular polarization MIMO communication system for watercraft according to claim 1, characterized in that, The orthogonal dual-polarized antenna is mounted on a stable platform; the stable platform includes an azimuth axis, and because the antenna transmits and receives dual circularly polarized waves, no roll compensation axis is required; the stable platform also includes an optional pitch axis, and the pitch axis does not have roll compensation functionality.

5. The dual circular polarization MIMO communication system for watercraft according to claim 1, characterized in that, It also includes a second orthogonal dual-polarized antenna and a second 90° 3dB orthogonal hybrid bridge; the two orthogonal dual-polarized antennas and the two 90° 3dB orthogonal hybrid bridges correspond one-to-one, and each independently completes the conversion of linear polarized signals to circular polarized signals, forming two independent left-hand circular polarized and right-hand circular polarized MIMO channels.

6. The dual circular polarization MIMO communication system for watercraft according to claim 1, characterized in that, The two orthogonal dual-polarized antennas are electrically connected to the two 90° 3dB orthogonal hybrid bridges using a cross-polarization combination. Specifically, for H / V dual-polarized antennas, the H port of the first antenna and the V port of the second antenna are electrically connected to the same coupling port of the 90° 3dB orthogonal hybrid bridge, and the V port of the first antenna and the H port of the second antenna are electrically connected to the coupling port of another 90° 3dB orthogonal hybrid bridge. For ±45° dual-polarized antennas, the +45° port of the first antenna and the -45° port of the second antenna are electrically connected to the same coupling port of the 90° 3dB orthogonal hybrid bridge, and the -45° port of the first antenna and the +45° port of the second antenna are electrically connected to the coupling port of another 90° 3dB orthogonal hybrid bridge.

7. The dual circular polarization MIMO communication system for watercraft according to claim 1, characterized in that, In transmit mode, the 90° 3dB orthogonal hybrid bridge converts the two MIMO signals output by the microwave communication transceiver into orthogonal linearly polarized signals with equal amplitude and a phase difference of ±90°. These signals are then radiated by the orthogonal dual-linear polarized antenna to form left-hand and right-hand orthogonal circularly polarized waves. In receive mode, the orthogonal dual-linear polarized antenna receives the spatial circularly polarized wave, which is then decomposed and restored into two independent MIMO signals by the 90° 3dB orthogonal hybrid bridge and sent to the microwave communication transceiver for processing.

8. A dual circular polarization MIMO communication method for watercraft, applied to the dual circular polarization MIMO communication system for watercraft as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Connect the two polarization output ports of the orthogonal dual-polarized antenna to the two coupling ports of the 90° 3dB orthogonal hybrid bridge in a one-to-one correspondence; the orthogonal dual-polarized antenna is an H / V dual-polarized antenna or a ±45° dual-polarized antenna; the 90° 3dB orthogonal hybrid bridge is set independently or integrated internally, and it is selected from equivalent devices that can realize equal amplitude, 90° phase difference orthogonal excitation; S2. Connect the two combining ports of the 90° 3dB orthogonal hybrid bridge to the MIMO port of the microwave communication transceiver to construct a dual circularly polarized MIMO communication link; S3. In the transmit state, the 90° 3dB orthogonal hybrid bridge converts the two MIMO signals into orthogonal linearly polarized signals with equal amplitude and a phase difference of ±90°, which are then radiated by the orthogonal dual-linear polarized antenna as either a left-hand circularly polarized wave or a right-hand circularly polarized wave. In the receive state, the orthogonal dual-linear polarized antenna receives the spatial circularly polarized wave, which is then decomposed and restored by the 90° 3dB orthogonal hybrid bridge into two independent MIMO signals, which are then sent to the microwave communication transceiver for processing.

9. The dual circular polarization MIMO communication method for watercraft according to claim 8, characterized in that, It also includes a second orthogonal dual-polarized antenna and a second 90° 3dB orthogonal hybrid bridge; the two orthogonal dual-polarized antennas and the two 90° 3dB orthogonal hybrid bridges correspond one-to-one and work independently to achieve independent radiation of left-hand circularly polarized waves and right-hand circularly polarized waves, respectively.

10. The dual circular polarization MIMO communication method for watercraft according to claim 8, characterized in that, It also includes a second orthogonal dual-polarized antenna and a second 90° 3dB orthogonal hybrid bridge; the two orthogonal dual-polarized antennas and the two 90° 3dB orthogonal hybrid bridges are electrically connected in a linear polarization cross combination manner to optimize port isolation.

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