Circular polarisation has opened a new door in underground mining and tunnelling communication. It allows antenna signal to travel through tunnels, avoiding potential obstructions, and creating a reliable signal throughout.
The radio waves transmitted with this type of polarisation are not constrained to just linear or horizontal situations when bouncing off the walls. They create a mirror effect, making a cylinder shape as they travel down the tunnel. The radio waves can radiate around obstacles, enabling them to adapt well in various tunnel dimensions. Circular polarisation prevents these waves from fading, which they are likely to do with vertical and horizontal polarisation, and allows those working in these conditions to maintain constant communication and situational awareness.
The Poynting MinePoynt HELI antennas have been designed for use in mining and tunnelling industries, with patented circular polarisation technology.
There’s been numerous tests performed in mines over the past few years to examine the benefits of using these antennas. One of these tests involved a large train moving through a tunnel. Significant signal loss was expected, but was unchanged due to the way the signal propagated around the obstacle.
Within these tunnels there are lots of potential issues that can affect the strength of the signal, including:
- Reflective tunnel surfaces
- High clutter environments that occupy and obstruct the standard propagation paths
- Narrow spaces
- No line of site, due to twisting tunnels and irregular turns
- Irregular dimensions and shapes of tunnels
The HELI antennas have been designed to overcome these obstructions and maintain a reliable signal within these harsh environments.
TYPES OF POLARISATION
Linear Polarisation (vertical and horizontal)
- Rotates unpredictably down a tunnel
- The propagation is affected by tunnel dimensions and surfaces
- Signal is unreliable and can fade
- Unable to propagate around obstacles
- First reflections cause significant signal interference
Circular Polarisation
- Contains all polarisations, making significantly more reliable radio links
- Propagation adapts better within tunnel dimensions
- Circular polarisation propagates past obstacles and obstructions more reliably
- You can get both left-hand and right-hand circular polarisation
The MinePoynt HELI range has been established for several years, and is deployed in a number of mines and tunnels across Europe, Australia, Africa, USA, Canada and more. The range offers both dual-band 2.4/5GHz and LTE/5G antennas in a smaller size enclosure compared to their bigger brothers, the popular HELI-3, HELI-4 and HELI- 8. The antennas offer medium to high gain, whilst providing the smallest possible installation height for mounting on tunnel roofs and walls.
