Radio output RF signal power, through the feeder (cable) to the antenna, from the antenna in the form of electromagnetic radiation. After the electromagnetic wave arrives at the receiving location, Digital TV Antenna the antenna is then followed (only a small fraction of the power is received) and sent to the radio receiver through the feeder. It can be seen that antennas are an important radio device for transmitting and receiving electromagnetic waves, Digital TV Antenna and there is no radio communication without antennas.
Antenna variety, for different frequencies, different purposes, different occasions, different requirements, Digital TV Antenna such as the use of different circumstances.
For many varieties of antennas, proper classification is necessary:
* Classification by use: can be divided into communication antennas, Digital TV Antenna TV antennas, radar antennas, etc.
* Classification by Working frequency bands: can be divided into shortwave antennas, ultrashort wave antennas, microwave antennas, etc.
* According to directional classification: can be divided into omnidirectional antenna, directional antenna, etc.
Symmetrical oscillator is a classical and widely used antenna so far, Digital TV Antenna a single half wave symmetrical oscillator can be used alone or as a parabolic antenna feed, can also use multiple half wave symmetric oscillator to form antenna array.
The oscillator with equal length of two arms is called symmetrical oscillator.
One of the basic functions of the transmitting antenna is to radiate the energy from the feeder to the surrounding space, and the basic function is to radiate most of the energy toward the desired direction. Digital TV Antenna The vertically placed half wave symmetrical oscillator has a flat “doughnut”
The smart antenna is composed of three parts: the antenna array which realizes the signal space over sampling, the beam forming network with weighted merging of the output of each array, Digital TV Antenna and the control part of the weight value. For easy analysis, Sidelobe control and DOA (arrival direction) estimation in mobile communication applications, the antenna array adopts uniform linear array or uniform circular array. The control part (ie part of the algorithm) is the core of the smart antenna, Digital TV Antenna its function is based on the signal environment, select some criteria and algorithm calculation weights.
The predecessor of Smart antenna technology is a beamforming (beamforming) technology. The beam forming technology is the channel information between the sender and the receiver at the current position of the sender, Digital TV Antenna adjusts the parameters of the signal transmission, and makes the RF energy to the receiver’s position, so that the signal received by the receiver is of good quality, Digital TV Antenna and finally can maintain the higher throughput. The technology is divided into two kinds: Chip mode (on-chip) and hardware smart antenna (On-antenna).
Post time: Sep-25-2018