Multi-GNSS High Precision Antenna Research Progress

　　Research progress of multi-GNSS high-precision antennas

　　At a time when the global navigation satellite system (GNSS) is widely used, multi-GNSS high-precision antennas are core components for improving positioning accuracy, stability and reliability, and their technological development has attracted much attention. From the reliance of self-driving cars on precise positioning under complex road conditions, to the demand for high-precision collection of geographic information in the surveying and mapping field, to the efficient sowing and spraying of pesticides by drones in agriculture based on precise positioning, multi-GNSS high-precision antennas play an irreplaceable role. In-depth analysis of its research progress will help grasp the future direction of this field and provide strong support for the development of related industries.

　　II. Progress in technological innovation

　　2.1 Deepening of multi-band fusion technology

　　In order to achieve efficient reception of multi-system signals such as GPS, Beidou, Galileo, and GLONASS, multi-band fusion has always been a key technical direction. In recent years, this technology has made continuous breakthroughs. Zhejiang Spacetime's dual-frequency low-orbit occultation antenna (CN114171907B) not only covers low-orbit satellite signals, but also is compatible with multiple frequency band signals through innovative structures such as multi-layer patches and four-arm spirals, significantly improving positioning reliability in complex environments. From the patent application trend, the number of patent applications for multi-GNSS high-precision antennas covering the entire frequency band continues to rise, reflecting the strong market demand for full compatibility with multi-system and multi-frequency band signals. Current research is moving towards further optimizing multi-frequency band signal processing algorithms to improve the coordination efficiency between signals in different frequency bands, reduce signal interference, and achieve more accurate positioning.

　　2.2 Innovation of anti-interference technology

　　In complex electromagnetic environments, anti-interference technology is an important guarantee for multi-GNSS high-precision antennas. Traditional anti-interference technology is mostly based on filtering principles, and has gradually evolved towards advanced directions such as adaptive zeroing and machine learning-driven interference detection. U-blox's patent (CN119335561A) uses machine learning to optimize signal processing, which can intelligently detect and suppress interference signals; China Railway Construction Corporation's ambiguity fixation method (CN118011445B) combines INS (inertial navigation system) with anti-interference technology to maintain signal stability in an interference environment. Recently, Wang Feixue's team at the National University of Defense Technology has achieved innovative results and proposed the concept of "using jitter for accuracy". By introducing controllable linear micro-jitter at the signal receiving end, the multipath signal phase changes rapidly, and efficient averaging and error cancellation are achieved in the signal processing stage. Experiments show that this method can enable ordinary vehicle-mounted antennas (costing about 7 yuan) to achieve basically the same two-dimensional positioning accuracy as stationary high-precision monitoring antennas (costing about 50,000 yuan), providing a new path to solve the problem of multipath errors in complex obstruction environments.

　　2.3 Advanced high-precision measurement antenna technology

　　High-precision measurement antennas are an important branch of multi-GNSS high-precision antennas. Thales has 9 key patents in the field of quadrifilar helical antennas by optimizing the feeding structure, ensuring the stability of the high-precision phase center and guaranteeing the measurement accuracy; Hexin Xingtong's patent (CN109856802B) uses multi-antenna double-difference observation equations to solve the baseline vector, effectively improving the accuracy of attitude measurement. Today, researchers are committed to further improving the long-term stability of the antenna phase center and exploring new materials and manufacturing processes to reduce the impact of environmental factors on antenna performance. At the same time, for multipath effect suppression, more complex and efficient algorithms and structures are continuously developed, such as using intelligent algorithms to adjust antenna parameters in real time to adapt to multipath interference in different measurement environments.

　　2.4 Breakthroughs in miniaturization and integration technology

　　With the rise of mobile devices and portable applications, miniaturization and integration have become an inevitable trend in the development of multi-GNSS high-precision antennas. Tesla's on-board antenna integrates heating function to adapt to extreme weather, and also integrates the antenna with the RF front end and signal processor to reduce power consumption and cost. The CXP-FUSION micro high-precision positioning intelligent terminal launched by Chengxin Zhilian and Shuobei has innovatively integrated the satellite-inertial navigation system (GNSS + IMU) with the vehicle antenna function. While achieving highly integrated functions, the product size is reduced to about 75×75×25mm, which is smaller than most P-BOX products on the market, effectively reducing the space occupied by the vehicle and improving the overall performance and reliability of the system. In the process of miniaturization, researchers continue to explore new materials, such as new ceramic materials with high dielectric constant and low loss, to maintain good signal reception and radiation performance while reducing the size of the antenna. In terms of integration, the research focus is on optimizing the electromagnetic compatibility between different functional modules and improving the stability and reliability of the integrated system.

　　3. Application expansion progress

　　3.1 Wide application in the field of intelligent transportation

　　In the field of intelligent transportation, multi-GNSS high-precision antennas play a key role. In autonomous vehicles, high-precision positioning is the basis for achieving safe and reliable autonomous driving. Huawei's multi-GNSS high-precision antenna patent technology (CN119667727A) dynamically adjusts antenna performance to adapt to different driving scenarios and has been applied to vehicle navigation, improving positioning accuracy and response speed. The application of CXP-FUSION micro high-precision positioning intelligent terminal in vehicles can provide real-time continuous high-precision, high-reliability centimeter-level positioning, vehicle speed and posture information, even in complex environments where satellite signals are interfered, blocked or lost, such as tunnels, urban canyons and underground parking lots, it can still rely on inertial navigation technology to continue to provide reliable positioning and navigation services for vehicles. In addition, the intelligent electric motorcycle operation and maintenance system based on Beidou single-frequency RTK (real-time differential positioning) and navigation maps, by equipping the vehicle's central control with a single-frequency RTK chip and a high-precision GNSS antenna, combined with the Beidou ground-based augmentation system and IoT devices, can achieve second-level reporting of positioning information, effectively identify vehicle parking, illegal behavior, etc., and promote the development of intelligent transportation in the field of two-wheel travel.

　　3.2 Accuracy Improvement in Surveying and Mapping and Geographic Information Fields

　　Surveying and mapping and geographic information fields have extremely high requirements for high-precision positioning. Trimble has many high-precision measurement antenna patents in the surveying and mapping field. By optimizing choke design and other technologies, it effectively suppresses multipath effects and occupies an important position in the professional surveying and mapping market. Unicore Starlink's multi-antenna collaborative positioning patent technology (CN109856802B) provides strong support for my country's Beidou satellite navigation system in high-precision surveying and mapping, and realizes high-precision positioning and attitude measurement. my country's first sub-meter resolution optical stereo mapping satellite, Gaofen-7, uses high-precision GNSS antennas to obtain high-resolution stereo mapping remote sensing data and high-precision laser altimetry data, achieving 1:10,000 stereo mapping, which improves the accuracy and efficiency of my country's geographic information collection. In addition, the "General Specification for Beidou Global Navigation Satellite System (GNSS) High-Precision Navigation Antennas" drafted by the Guangzhou Institute of Metrology will be implemented from June 1, 2023, providing a guarantee for the standardization and high-quality development of high-precision antennas in the field of surveying and mapping and geographic information.

　　3.3 In-depth penetration in the field of precision agriculture

　　Precision agriculture relies on high-precision positioning to achieve refined management of farmland operations. Based on Beidou's precision agriculture technology, multi-GNSS high-precision antennas are used to support farmland automation, intelligent sowing, irrigation, area calculation, nutrient determination, variety analysis, pest and disease monitoring, growth analysis, etc., realizing agricultural informatization and precision. For example, agricultural drones equipped with multi-GNSS high-precision antennas can accurately spray pesticides and sow in farmland according to positioning information, avoid drug waste and uneven sowing, improve agricultural production efficiency, and reduce the impact on the environment. In terms of grain storage, the Guangzhou Institute of Metrology uses metrology technology to ensure the accuracy of grain storage environment monitoring by deploying temperature measurement antennas and other equipment in grain warehouses to ensure grain preservation and safe storage.

　　4. Future Research Prospects

　　4.1 Overcoming Technical Gaps

　　Although multi-GNSS high-precision antenna technology has made significant progress, there are still some technical gaps. In terms of beamforming technology, there are few patents for the application of beamforming technologies such as phased arrays in multi-GNSS high-precision antennas, especially in terms of low-cost integration, which needs to be broken through. Although phased array technology can achieve flexible beam pointing and shaping, its complex structure and high cost limit its wide application. In the future, it is necessary to develop low-cost and miniaturized phased array antenna solutions. With the development of low-orbit satellite constellations, the design of antennas with anti-multipath effects suitable for low-orbit environments is not yet mature. The signal propagation environment of low-orbit satellites is complex and the multipath effect is serious. The existing multipath suppression technology is difficult to meet the needs, and new antenna structures and algorithms need to be developed in a targeted manner. In terms of adaptability to extreme environments, the reliability technology of antennas, such as material weather resistance, needs to be further improved in areas with high temperature, high humidity or dense electromagnetic interference. At present, the performance of antenna materials is prone to degradation in extreme environments. The development of high-performance, extreme environment-resistant antenna materials and protection technologies is an important research direction in the future.

　　4.2 Focus on emerging technology directions

　　In the future, multi-GNSS high-precision antennas will develop towards AI-driven smart antennas. By combining AI technologies such as machine learning and deep learning, antennas can sense environmental changes in real time and automatically optimize parameters, such as adjusting beam direction and gain, to adapt to different signal propagation environments and user needs. U-blox's interference detection model has demonstrated the application potential of AI in antenna anti-interference. In the future, AI will play a greater role in the all-round performance optimization of antennas. Chip-level integration is also an important trend. Highly integrating antennas with RF front-ends, signal processors, etc. on chips can reduce power consumption, reduce volume and cost, and improve the overall performance and reliability of the system. Huawei and other companies have explored this aspect. With the advancement of integrated circuit technology, chip-level integrated multi-GNSS high-precision antennas will be more widely used. In addition, with the increase in environmental awareness, the application of green manufacturing technology in the field of multi-GNSS high-precision antennas will be valued. Using recyclable materials to manufacture antennas and using low-energy consumption processes in the production process can not only reduce environmental impact but also meet the requirements of sustainable development. It will become an important development direction for antenna manufacturers in the future.