A feed line is a cable that transmits radio signals to a receiver or transmitter from a radio antenna. The feed line connects the antenna with the transmitter, receiver, or transceiver. It is commonly used in wireless communication and broadcasting antenna systems. It transmits radio frequency energy from the antenna to the receiver. It does not emit any energy when properly operated.
Transmission lines and feed lines are both used to describe RF transmission lines.
Techopedia explains Feed Line
A feed line is a specialized cable that connects an antenna to the transmitter or receiver in a wireless or radio communication system.
The most commonly used feed lines include:
- Coaxial cable, which is made up of four components: the conductive center wire, the plastic insulation surrounding the wire, the copper shielding on the insulation, and the tough outer covering.
- Twin-lead, a wire enclosed in plastic, marked at the same distance along the entire line.
- Ladder line, also known as the parallel conductor feeding line, consisting of two conductors separated by insulating bars.
- Waveguides, used for microwave frequencies.
Feed lines are specialized cables that carry radio frequency voltages from one end of the line to the other. The antenna and feed line must have the same characteristic impedance to efficiently transfer RF power. The RF energy will be reflected back toward the transmitter if the impedances are not matched. This can lead to energy waste and excessive heating of the transmitter. An antenna tuner can be used to make the necessary changes for energy transfer.
When using feed lines, it is important to keep in mind:
Signal loss increases with frequency.
Signal loss also increases for longer feedlines, as the signal resistance increases along with the length.
This post was written by Justin Tidd, Director at Becker Mining Communications! For over 15 years, Becker Communications has been the industry’s leader in leaky feeder systems mining and electrical mining communication systems. As they expanded into surface mining, railroads, and tunneling they added wireless communication systems, handheld radios, tagging, and tracking systems, as well as gas monitoring.