Leaky feeder coaxial cables are used in radio communication systems to allow the transmission of signals over a sizable subterranean area. These cables are surrounded by what is known as dielectric material, which helps reduce the amount of signal that is lost through coupling between different components in the cable. This reduction in signal loss is referred to as coupling loss. The coupling loss can be put in proportion to the transmission signal length.
Coupling loss is generally from 50 db to 8db at a distance of 1.5 meters. The difference between a coupling loss to adjacent cables depends on the grading quality, and this level is usually at 10 dB for a spliced line. The amount of coupling loss is determined by the cable’s dielectric material, conductor size and spacing, shielding characteristics, and other factors. The level of coupling loss can be reduced by using an increased number of cables or optimizing the design properties such as size, conductor spacing, and shield.
When the power is insufficient in one grading section, power supply units can be installed in the middle of the route to provide the cable’s power supply in each direction.
50Ω N type connectors are the primary way two coaxial cables are connected. Adjusting the phase of each connection cable is often necessary to reduce the amount of signal loss. This is often done using phase shifters connected to the ends of each coaxial cable.
To mitigate a coupling loss signal issue, antennas can be moved to different locations where the signal strength is strong, and there is less interference. Also, amplifiers can increase the transmission level of a given frequency band or extend line lengths. Doing this will help reduce any coupling loss issues in leaky feeder systems.
An excellent way to ensure that leakage levels are minimized, and an acceptable level of coupling loss is achieved is by performing regular maintenance on cables, such as inspecting for water and corrosion damage and replacing damaged components. Using high-quality components and materials during installation will also help minimize a system’s coupling loss. In addition, regularly testing the cables for proper connections, signal levels, and frequencies can help ensure that any potential issues are addressed quickly and efficiently.
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.