Some essentials about the feeder cable

Feeder cables are used to transmit signal between the input/output ports in the emitter and the antenna. It is very important that the loss in the transmission should be subject to any interference and affect no spurious signal. Hence the feeding line should be strip transmission line. Transmission cables with lengths equal to or longer than the wavelength of the transmitted signal are called long transmission cables or simply long cables.

Ultra-short wave transmission lines fall into two categories: parallel and coaxial (for types, wave guide or micro-strip). Parallel feeder cables can not be used for UHF frequencies, due to heavy power loss. For UHF frequencies, the feeder cables are usually coaxial. The coaxial cable is made up of two conducting lines and the shield copper net. The copper net is grounded. The two conducting lines are unbalanced, so the transmissions are called unbalanced or

unsymmetrical. Coaxial cables have a wide range of working frequencies and the loss is small. Coaxial cables can shield electrostatic coupling, but they can be affected by magnetic fields. In

application, coaxial cable should be isolated from high current power lines and low-frequency signal lines.

Good knowledge sharing

useful document, thanks