Car antenna
Vehicle antenna is refers to the mobile communication antenna design is installed on the vehicle, is the most common sucker antenna. Because the sucker antenna installation put easily, so in some simple set occasions sucker antenna is often used instead of base antenna. The on-board antenna structure have shortened, a quarter wavelength, central loading, five 8 half wavelength, double wavelength in the form of the antenna, in theory, in turn, increase their efficiency, the same working frequency band of the antenna length also increases in turn. Due to limited the vehicle itself is high, coupled with a long antenna in the vehicle at high speed wind resistance, little tunnel, into the underground garage are problem, so the car antenna is not as long as possible, general requirements car antenna is not more than 70 centimeters, the van antenna shorter class requirements. Although small antenna size, shorten type gain is not high, but suitable for use in the occasion of hidden antenna. General police vehicles the installation of a high gain antenna is recommended, especially in the activity area larger vehicles, more than 350 MHZ high gain antenna can be divided into five 8 wavelength loading form, at the top half wavelength distance from the antenna has a loading coil. 400 MHZ band double half wave antenna has high gain, its appearance is characterized by antenna vibrator has two loading coil. Five 8 wave antenna and central type loaded antenna also has a higher gain, and the price is cheaper, so widely used. In as a temporary fixed platform can consider to choose high gain antenna using occasions of sucker antenna, the length of the antenna don't have too many restrictions. Since sucker antenna is designed according to the car use environment under which when used as a fixed so suck a radius greater than 1 m metal plate (such as iron) can have a better effect. Due to the import original vehicle antenna price advantage is very expensive and not stand out, so generally choose domestic car antenna. In antenna selection stage mainly refer to the appearance and the gain of the antenna. Suggest choose big manufacturer of famous brand products, authenticity is higher, they provide the parameters of the manufacturing process is guaranteed. If it is bulk purchase can completely to professional custom by using frequency antenna manufacturer, in order to obtain the best use effect.
Base station antennas
Base station antenna has a key role in the whole communication system, especially as the communication hub of communication stations. High gain antenna can not only increase the radio coverage area, and also to have certain of received signal amplification, can receive weak uplink signals better, improve the quality of mobile station and base station of wireless communication. Base stations are generally choose high-gain antenna, with the condition of the interference can be according to the actual situation considering adding narrow-band filter to reduce the influence of interference. Common base stations
FRP antenna with omnidirectional basic no directional antenna, is suitable for base station location is located in the center of communication network. Due to glass fiber reinforced plastic antenna installation is easy, so widely used in various types of base stations. FRP antenna gain up to about 10 db, the higher the gain antenna is, the longer average gain for 5 to 6 db gain of FRP antenna on the length and the price is competitive, manufacturing technology is more mature, more. This kind of antenna in addition to the electrical properties, the quality of the outer FRP radome is there much difference, some bad products in the sun after a year of outer glass fiber reinforced plastic cracking would happen lead to scrap the whole antenna, some big brands of FRP antenna on quality more secure.
Directional antenna is equivalent to the energy concentrated on multiple directions to one direction, has the characteristics of the main direction of radiation gain high, commonly used is yagi antenna. Yagi antenna unit number of the more its gain is higher, also suitable for point-to-point communication over a long distance and located at the edge of the network stations use. Suit is located in remote areas of directional contacts with the superior branch of police station, used properly the effect will be better than that of glass fiber reinforced plastic antenna.
Sihuan array antenna is characteristic of large power, high gain, under direction gain adjustable, suitable for communication hub and the city bureau (bureau) and relay stations, but the price is quite high. 4th ring oscillator array antenna of four launch direction adjustable, when four oscillator interval of 90 degrees to install the basic characteristics of the antenna is omni-directional, when four vibrator all installed in the same direction when the directional antenna characteristics of gain in the main radiation direction at the same time to improve. The gain direction adjustable features can be used to better adapt to the rules of the service area. If sihuan array antenna gain is high enough to consider eight ring array antenna and its properties are similar to sihuan array but provides a higher gain. General 350 MHZ band sihuan array gain is 8 db (omnidirectional) / 10 db (orientation), eight ring array gain of 12 db (omnidirectional) / 15 db (orientation).
参考网址：http://www.crtegd.com/dgz-8.asp