What is a day-feed system

The antenna-fed system refers to electromagnetic waves radiating from the antennas to the surrounding space. Electromagnetic waves consist of electric fields and magnetic fields. It is stipulated that the direction of the electric field is the direction of the antenna polarization. The antennas commonly used are mono-polarized. The antenna and feeder systems are mainly composed of two kinds.

The antennas mainly include:

A) Sucker antenna: Affordable, easy to install, moderate gain, suitable for installation on mobile vehicles, or adsorbed on metal objects. General gain in 2.6dB, 5 db and several.

b) anti-theft antenna: Affordable, easy to install, gain the same sucker antenna, installed in the metal box outside the box can not be removed, it is called anti-theft antenna.

c The low gain omni-direction antenna: Gain is 3.5dB, the installation needs to have the fixed bracket, suitable for long-distance multiple point transmission.

D High-gain omni-direction antenna: Gain is 8.5dB, installation needs to have a fixed bracket, suitable for long-distance transmission of multiple points.

(e) directional antenna: The gain is very high, 12dB, the installation needs to have a fixed bracket, suitable for long distance fixed direction transmission.

Feeder mainly includes:

A) 50―3 (impedance 50ω, section 3) of the feeder loss for 0.2db/m.

b) 50―7 (Impedance 50ω, section 7) of the feeder loss for 0.1db/m

c) 50―9 (Impedance 50ω, section 9) of the feeder loss for 0.07db/m.

Feeder is an important equipment to connect the radio with the antenna. The feeder with different weight and different quality will have a great influence on the communication distance. The signal is transmitted in the feeder, in addition to the resistance loss of the conductor, as well as dielectric loss of insulating material. Both of these losses increase with the increase of feeder length and the increase of working frequency.