1, the concept of distinction Passive antenna: pure metal body, is a variety of common antenna. Active antenna: add amplifier behind this common antenna, equipped with amplifier's power supply, used to improve the sensitivity and reduce the signal-to-noise ratio.
2、Shape distinction
Because the active antenna increases the amplifier, the growth rate is higher, most of the active antenna volume and size is larger than the passive antenna. Important point: In addition, the appearance of the active usually indicates that the voltage (VCC), no passive
3, graphical analysis of the differences Appearance is not much different, but the circuit active circuit than passive circuit increases the low noise amplification and power supply. The following is the active antenna circuit logo :
This is the u-blox AEK-4H standard evaluator GPS active antenna circuit architecture can see the active antenna only through the coaxial cable connected to the rear RF circuit; the cable mainly plays two roles: (1) active antenna LNA DC power supply; (2) through the beam antenna to receive and through the method of GPS RF signal.
Then DC and RF in the same axis GPS how to isolate the signal? It is realized by inductance and capacitance, and inductance is realized by microstrip line.
The performance of GPS antenna affects the performance of GPS antenna mainly has the following aspects:
1, ceramic sheet: the ceramic powder is good or bad as well as the sintering process directly affects its performance. Now the ceramic sheet used in the market is mainly 25×25mm, 18×18mm, 15×15mm, 12×12mm. the larger the area of ceramic sheet, the larger the dielectric constant, the higher the resonance frequency, the better the acceptance effect. Most of the ceramic sheet is square design to ensure that the resonance in the XY direction is basically the same, so as to achieve the effect of uniform star receiving.
2, silver layer: ceramic antenna surface of the silver layer will affect the antenna resonance frequency. gps ceramic chip frequency point accurately landed 1575.42MHz, but the antenna frequency point is very easy to be affected by the surrounding environment, especially when assembled in the whole machine, must be adjusted through the adjustment of the shape of the silver coating to adjust the frequency point of 1575.42MHz. so gps purchasing antenna, the whole machine must cooperate with the antenna manufacturer, the antenna manufacturer. Provide samples of the whole machine for testing.
3, feeder: ceramic antenna through the feeder to collect the resonance signal and sent to the back end. Due to the antenna impedance matching, the feed line is usually not in the center of the antenna, but in the XY direction to do a small adjustment. This impedance matching method is simple and adds no cost. Movement in only one axis direction is called a single bias antenna and movement in both axes is called double bias.
4, amplification circuit: carrying ceramic antenna PCB shape and area GPS When the background is touchdown bounce, it has the characteristics of touchdown bounce 7 × 7cm uninterrupted earth when the efficiency of the patch antenna can be maximized. Although limited by factors such as appearance and structure, try to maintain a fairly large area and uniform shape. Amplifier circuit gain must be selected to match the back-end LNA gain.Sirf's GSC3F The total gain before the signal input must not exceed 29dB, otherwise the signal oversaturation will produce self-excitation.There are four important parameters of a GPS antenna: Gain (Gain), Standing Wave (VSWR), Noise figure (Noise figure), Axial ratio (Axial ratio). Axial ratio is an important indicator of the difference in signal gain in different directions. Since satellites are randomly distributed over the hemispherical sky, it is very important to ensure the sensitivity of the antenna in all directions. Axial ratio is affected by antenna performance, appearance and structure, internal circuitry of the whole machine and EMI. How to choose passive antenna and active antenna?
5, the current market can produce their own GPS ceramic antenna manufacturer is mainly da gamma navigation, jiaxing jiali electronic, jiabang, jiakang electronic waiting for manufacturers. Most manufacturers buy ceramic parts from home and abroad, and with the design of the amplifier circuit. Super smart terminals are becoming more and more the trend of The New York Times, and the narrow space puts high demands on the size of the accessories. The initial domestic technology is only 15×15mm or more mature, 10×10mm or more basically mature. At least can. 7 × 7mm yield will be low. 1, passive GPS antenna
The use of passive GPS antenna, directly connected to the module is only a ceramic piece to receive the satellite signal RF-IN feet of the sky, this connection is a simple structure, standardized 25 × 25 × 4mm ceramic piece of low cost, mature technology, small footprint, suitable for emphasizing the compact space GPS navigation products, Bluetooth GPS, cell phone GPS and other small GPS consumer products.
The layout of this antenna is from the antenna pins to the module RF-IN feet, this wire needs to be 50 ohm impedance matching, the antenna near the electromagnetic interference can not be. PCB design and the whole EMI design requirements are high, but if the design of the excellent passive antenna GPS products also have a very good performance results, energy saving.
2, active GPS antenna usually for equipment or vehicle-mounted machine, because the equipment and GPS receiver module before the distance is often, taking into account the convenience of installation may be more than 1 meter distance, in this case we can only choose active GPS due to the length of the antenna signal attenuation needs to be compensated for, there are generally two-stage low-noise amplifier (LNA) amplify the signal of the antenna front-end, the amplified signal through the cable output, the The cable is synchronized to provide the DC voltage required by the LNA.
As the antenna received signals in the active antenna receiver head to complete the signal reception and antenna amplification, away from the GPS device or other electrical equipment, the source of interference is minimal, and the installation location due to the antenna distance to extend the installation location can choose a very ideal environment, so the actual use of the signal is often felt stronger. Especially in the weak signal start-up due to the internal secondary amplification will also have a certain gain, often faster start-up time, but because of the internal secondary LNA, will also consume a certain amount of power, the performance of different manufacturers of products are not the same. Ceramic antenna sheet and ceramic antenna sheet is mainly affected by the active antenna performance LNA, and antenna design, impedance matching, screen spectrum testing, antenna fine-tuning and output line terminals.
Ltd. specializes in high-precision GNSS modules and wireless communication products, technology development and application promotion service providers, relying on the wireless communication technology in the field of research and development and promotion experience, Junoda established a technical team with rich experience in hardware and software development, aimed at domestic and foreign OEM / ODM customers and system integrators to provide high-quality, high-performance wireless modules and application We aim to provide high-quality, high-performance wireless modules and application programs to OEM/ODM customers and system integrators at home and abroad, and create long-term value for our customers!
The company mainly provides integrated antenna module, dual-frequency high-precision module, single-frequency high-precision module, Qianxun high-precision module, Zhongke micro-positioning module, U-BLOX positioning module, SICOM communication module, inertial navigation DR module, UW GNSS module, RTK differential module, 4G communication module and high-precision antenna, etc., and our products are well sold in Beijing, Shanghai, Shenzhen, Guangdong, Jiangsu, Zhejiang, Sichuan, Hunan and other parts of the country. Our GNSS modules are widely used in many application fields, such as drones, vehicle security monitoring and scheduling, automatic bus stop announcement, DVR, car DVD navigation, GPS electronic dog, synchronized timing, high-altitude balloon monitoring, engineering machinery, industrial automation, etc. In the field of wireless communication products, our company is closely involved in the development and production of wireless communication products, such as RTK differential modules, 4G communication modules and high-precision antennas.
In the field of wireless communication products, the company follows the latest development of international communication technology, introduces and acts as an agent for wireless communication modules that meet the market demand, and the products have a comprehensive layout from 2G, 3G, 4G, and are widely used in financial electronic payment, vehicle remote control, remote advertising information, repeater monitoring, mobile Internet terminals, smart home, remote medical care, network testing, enterprise information management, anti-theft alarm, Remote video transmission, intelligent meter reading, mobile computing, network navigation, voice phone, wireless gateway and other fields. Focus areas include video surveillance, network optimization, routers, POS and other M2M industry applications.
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