With the continuous development and improvement of satellite positioning technology, high-precision positioning technology has been applied to all walks of life. For example, high-precision positioning technology can be seen everywhere in the fields of Surveying and mapping, precision agriculture, UAV, unmanned driving and so on. Especially with the completion of the networking of the new generation of Beidou satellite navigation system and the arrival of the 5g era, the continuous development of Beidou 5g is expected to promote the wider application of high-precision positioning technology in the fields of airport dispatching, robot patrol inspection, vehicle monitoring, logistics management and so on. The realization of high-precision positioning technology is inseparable from the support of high-precision antenna, high-precision algorithm and high-precision board. This paper mainly introduces the development, application and technical status of high-precision antenna.
1. Development and application of GNSS high precision antenna
1.1 introduction to high precision antenna
In the field of GNSS, high-precision antenna is a kind of antenna with special requirements for the stability of antenna phase center. It usually cooperates with high-precision board to achieve centimeter or millimeter level high-precision positioning. In the design of high-precision antenna, there are usually special requirements for the following indexes of the antenna: antenna beam width, low elevation gain, out of roundness, roll off coefficient, front to back ratio, anti multipath ability, etc. These indexes will directly or indirectly affect the phase center stability of the antenna, and then affect the positioning accuracy.
1.2 application and classification of high precision antenna
High precision GNSS antenna was initially mainly used in the field of Surveying and mapping to achieve static millimeter positioning accuracy in engineering setting out, topographic mapping and various control measurements. With the increasing maturity of high-precision positioning technology, high-precision antenna is gradually applied in more and more fields, including continuous operation reference station, deformation monitoring, earthquake monitoring, surveying and mapping, UAV, precision agriculture, automatic driving field, driving test and training, engineering machinery and other industrial fields. There are obvious differences in the index requirements of antenna in different applications.
1.2.1 CORS system, deformation monitoring, seismic monitoring - reference station antenna
When the high-precision antenna is applied to the continuous operation reference station, the accurate position information is obtained through long-term observation, and the observation data is transmitted to the control center in real time through the data communication system. The control center calculates the error correction parameters in the area, and then passes through the ground-based enhancement system, wide area enhancement system, satellite based enhancement system, etc, Send the error information to the mobile station (client), and finally enable the user to obtain accurate coordinate information .
In the applications of deformation monitoring and earthquake monitoring, it is necessary to accurately monitor the deformation and detect small deformation, so as to predict the occurrence of natural disasters.
Therefore, in the design of high-precision antenna in applications such as continuous operation reference station, deformation monitoring and seismic monitoring, the first consideration must be its excellent phase center stability and anti multipath interference ability, so as to provide accurate position information for various enhancement systems in real time. In addition, in order to provide as many satellite correction parameters as possible, the antenna must receive as many satellites as possible. The four system full frequency band has become the standard configuration. In such applications, the reference station antenna (reference station antenna) covering the whole frequency band of the four systems is usually used as the observation antenna of the system.
1.2.2 survey mapping - built in survey antenna
In the field of Surveying and mapping, it is necessary to design a built-in measuring antenna which is easy to integrate. The antenna is usually built on the top of RTK receiver to realize real-time and high-precision positioning in the field of Surveying and mapping.
The main considerations in the design of built-in measurement antenna include frequency band coverage, beam coverage, phase center stability, antenna size, etc. especially with the popularization of Network RTK, the built-in measurement antenna of all Netcom integrating 4G, Bluetooth and WiFi gradually occupies the main market share. It has been favored by the majority of RTK receiver manufacturers since its launch in 2016, It has been widely used and popularized.
1.2.3 driving test, driving training, unmanned driving - external measuring antenna
The traditional driving test system has many disadvantages, such as high investment cost, high operation and maintenance cost, great impact by the environment and low accuracy. After the high-precision antenna is applied to the driving test system, the driving test system changes from manual evaluation to intelligent evaluation, with high evaluation accuracy, which greatly reduces the human and material cost of the driving test.
In recent years, unmanned systems have developed rapidly. In unmanned driving, the positioning technology of RTK high-precision positioning and inertial navigation combined positioning is usually used, which can achieve high positioning accuracy in most environments.
In driving test, driving training, unmanned driving and other systems, the form of external measurement antenna is often used. The antenna needs to have multi system and multi frequency working frequency band, which can achieve high positioning accuracy, have certain suppression ability to multipath signals, and have good environmental adaptability. It can be used for a long time in outdoor environment without failure.
1.2.4 UAV - high precision UAV antenna
In recent years, the UAV industry has developed rapidly. UAVs have been widely used in agricultural plant protection, surveying and mapping, power line patrol and other scenes. In such scenes, only equipped with high-precision antenna can ensure the accuracy, efficiency and safety of various operations. Due to the characteristics of UAV such as high speed, light load and short endurance, the design of UAV high-precision antenna mainly focuses on factors such as weight, size and power consumption, and realizes broadband design as much as possible on the premise of ensuring weight and size.
2. Technical status of GNSS antenna at home and abroad
2.1 technical status of high-precision antenna abroad
Foreign countries began to study high-precision antenna earlier, and also developed a series of high-precision antenna products with good performance, such as novatel's GNSS 750 series choke antenna, Trimble's zepryr series antenna, Leica AR25 antenna, etc., among which there are many antenna forms with great innovative significance. Therefore, for a long time in the past, China's high-precision antenna market was monopolized by foreign products. However, in the past decade, with the rise of a large number of domestic manufacturers, foreign GNSS high-precision antennas have basically no advantages in performance. On the contrary, domestic high-precision manufacturers have begun to explore the market abroad.
In addition, some new GNSS antenna manufacturers have been developed abroad in recent years, such as maxtena, tallysman, etc. their products are mainly small GNSS antennas for UAV, vehicle and other systems. The antenna form is usually microstrip antenna with high dielectric constant or four arm spiral antenna. Foreign manufacturers have no advantages in the design technology of such antennas, Domestic and foreign products are entering a period of homogeneous competition.
2.2 technical status of domestic high-precision antenna
The commercialization of domestic high-precision antenna started late, but developed rapidly. In the past decade, a number of domestic high-precision antenna manufacturers began to grow, such as Huaxin antenna, zhonghaida, Dingyao, Jiali electronics, etc., and developed a series of high-precision antenna products with independent intellectual property rights.
For example, in the field of reference station antenna and built-in measurement antenna, Huaxin's 3D choke antenna and all Netcom composite antenna not only have the performance up to the international leading level, but also have high product reliability, long service life and extremely low failure rate, which can meet various environmental applications.
In vehicle, UAV and other industries, the design technology of external measurement antenna and four arm spiral antenna has been relatively mature, and has been widely used in driving test system, unmanned driving, UAV and other industries, and achieved good economic and social benefits.
3. Current situation and Prospect of GNSS Antenna Market
In 2018, the total output value of China's satellite navigation and location services industry reached 301.6 billion yuan, an increase of 18.3% over 2017 , and will reach 400 billion yuan in 2020; In 2019, the total output value of the global satellite navigation market will be 150 billion euros, and the number of GNSS end users will reach 6.4 billion; Under the background of the global economic downturn, GNSS industry is one of the few industries rising against the trend. The European Bureau of global navigation satellite systems predicts that in the next decade, the total output value of the global satellite navigation market will double to more than 300 billion euros, and the number of GNSS terminals will increase to 9.5 billion.
In the global satellite navigation market, the terminal equipment used in road traffic, UAV and other fields is the fastest growing market segment in the next decade: intelligent and driverless vehicles are the main development direction of road vehicles in the future. Vehicles with automatic driving ability must be equipped with GNSS high-precision antenna. Therefore, there is a huge demand for GNSS antenna in the automatic driving market. With the continuous development of China's agricultural modernization, the consumption of UAVs equipped with high-precision positioning antennas such as plant protection UAVs will continue to grow.
4. Development trend of GNSS high precision antenna
After years of development, various technologies of GNSS high-precision antenna have been relatively mature, but there are still many directions to be broken through:
1. Miniaturization: miniaturization of electronic equipment is an eternal development trend, especially in applications such as UAV and handset, the demand for small-size antenna is more urgent. However, the antenna performance will be reduced after the antenna is miniaturized. How to reduce the antenna size on the premise of ensuring the comprehensive performance is an important research direction of high-precision antenna.
2. Anti multipath Technology: anti multipath technology of GNSS antenna mainly includes choke technology , artificial electromagnetic material technology  , etc., but they all have the disadvantages of large size, narrow bandwidth and high cost, and can not realize universal design. Therefore, anti multipath technology with miniaturization and broadband needs to be studied to meet various application requirements.
3. Multifunction: Nowadays, in addition to GNSS antenna, more than one communication antenna is integrated in various equipment. Different communication systems may produce various signal interference to GNSS antenna, affecting normal satellite reception. Therefore, the integrated design of GNSS antenna and communication antenna is realized through multi-functional integration. The interference between antennas is considered in the design, which can improve the integration degree, improve the electromagnetic compatibility characteristics and improve the performance of the whole machine.
This paper briefly introduces GNSS high-precision antenna, focuses on its application in different industries and the technical status of high-precision antenna at home and abroad, and summarizes its market situation and development trend. With the popularization of 5g technology, Beidou 5g technology will further promote the application of high-precision positioning technology in more and more fields, and high-precision positioning antenna will also usher in greater development space.
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