Radio frequency friendly manhole cover developed25 October 2019
USA/Great Britain – Firbrelite has developed a radio frequency friendly manhole cover. The main benefit of the FL60RF cover is to enable real-time remote underground monitoring, so utility operators can keep track of water usage, sewer flow, floodwater, oil levels and similar. The company claims that mining and telecoms uses are also possible.
A spokesperson for the company said, “Traditional ductile iron and reinforced concrete manhole covers aren’t conducive to the transmission of RF signals. Metal reflects the signal, while concrete greatly weakens it (exhibits high attenuation coefficients). This means that the transmitted signal is greatly weakened, restricting range and functionality. Glass Reinforced Plastic (GRP) in contrast, absorbs far less of the signal (lower attenuation coefficient).”
A test case for the use of the system has been Cadiz in Spain, which implemented a drinking water monitoring system but encountered problems with the signal being blocked.