Antenna is kind of convertor, which translates the guided wave in the transmission line to the electromagnetic wave of unbounded media. And in wireless device, it is used to send or receive the components of electromagnetic wave. In addition, on the side of transporting energy by electromagnetic wave, no signal energy emission also depends on WIMAX antenna.1. The linear antenna is used in cable TV system, which is used to receive radio television signal. Some can receive more than two TV signals. The main kinds are dipole, batwing antenna, helical antenna and log periodic antenna and loop antenna. 2. Leaky antenna is mainly used to send microwave TV signal, micro strip antenna receives satellite TV signal. Their structure is that three-dimension of antenna element’s size is smaller than wavelength. Leaky antenna has leaks in the metal caving or the wall of antenna. Its working progress belongs to the hole diffraction of electric wave. Planar micro strip antenna is a new kind of new antenna which develops in the recent years, it is produced between the two metal thin layers of dielectric substrate, and produce it in printed board or microwave integrated circuit, while the other side is connected with the ground. The directivity should be enhanced, it can spread feed electricity by unit and distributor. The feature of linear antenna is that current spread along the straight line or curl line of antenna, and the size of antenna is less than wavelength.
Kinds of antenna
Dipole is one of the most classical and widely-use antenna, a single half-wave dipole can be used independently or used as feed source of parabolic antenna, and it can also consist of several dipoles. The basic function of radiator is to emission energy getting from feeder, and its second function is to send most of energy to all the needed directions.
The principles of antenna
When the conductor is connected with high-frequency current, it will produce electric field and magnetic field. At present, our mobile radio communication is damaged a lot heavy traffic area, for the reason that the angle of inclination is in great degree, the directional diagram of CDMA antenna is out of shape. In order to solve the problem of small volume of heavy traffic area, the distance should be shortened, and widen the angle of inclination. Therefore, electric tilt antenna and dual polarized antenna are suggested, and the other mechanical antenna can be installed in countryside. We should obey these principles to operate the antenna in order to make it work more effectively.
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