What is an antenna in a wireless video surveillance system?

An antenna is an inverter that transforms a guided wave propagating on a transmission line into an electromagnetic wave that propagates in an unbounded medium (usually free space) or vice versa. Components used to transmit or receive electromagnetic waves in radio equipment. Radio systems, radio, television, radar, navigation, electronic countermeasures, remote sensing, radio astronomy, and other engineering systems, all use electromagnetic waves to transmit information, rely on antennas to work. In addition, non-signal energy radiation also requires an antenna for transmitting energy using electromagnetic waves. The general antenna is reversible, that is, the same sub antenna can be used as both a transmitting antenna and a receiving antenna. The same antenna as the basic characteristic parameter for transmitting or receiving is the same. This is the reciprocity theorem of the antenna.

Antenna classification:

1, according to the nature of the work can be divided into transmitting antenna and receiving antenna.

2, according to use can be divided into communication antennas, broadcast antennas, television antennas, radar antennas.

3, according to the directionality can be divided into omnidirectional antennas and directional antennas.

4, according to the working wavelength can be divided into ultra-long wave antenna, long wave antenna, medium wave antenna, short wave antenna, ultra-short wave antenna, microwave antenna and so on.

5, according to the structure and working principle can be divided into line antennas and surface antennas. The characteristic parameters describing the antenna include pattern, directionality coefficient, gain, input impedance, radiation efficiency, polarization, and bandwidth.

6, according to the dimension of the points can be divided into two types: one-dimensional antenna and two-dimensional antenna 7, the antenna can be divided according to the different occasions: handheld antenna, vehicle antenna, base antenna three categories.