We use the HELI-003 (Poynting’s circular polarized Wi-Fi tunnel antenna) in coal mines for long straight runs giving us Wi-Fi coverage to approximately 1km.
“The HELI-004 (a smaller version of the HELI-3) is used in the tunneling projects where we don’t have a long a straight run. The tunnels are between 4 – 6m in diameter. These tunnels typically reach around 500-600m”.
Leigh Robinson, MST Systems Engineer (Australia)