Feasibility of using building reinforced steel bars to transmit signals

Intelligent control, building automation, networking is a basic provisions for modern building as well as railway station building. All these systems rely on a physical layer to transmit signal. Wire, wireless and powerline physical layer are commonly used. However, all these layers have their limitations and associated problems especially in existing building. Existing building without sufficient spare cable containment for future wiring, concrete chasing to install new cable containment is unavoidable for wiring new network cables. In view of higher cost and great nuisance to the occupant during concrete chasing, a feasibility study of using building reinforced steel bars to transmit signals is discussed in this paper for future application. The principle of signal transmission in reinforced steel bars is similar as signal coupling in a transformer by means of magnetic flux coupling. Signals are transmitted as magnetic flux by means of a transmission coil, which is installed through reinforced steel bar and cast-in the concrete. The magnetic flux shall flow all around the reinforced steel bars framework of the entire building. Another coil acting as receiver is installed in a remote area to couple the magnetic flux and transform the signals from the transmission coil. From the experiments in laboratory and two construction buildings, it proved that the building reinforced steel bars framework is feasible as a physical data transmission media. Signals injected into reinforced steel bars can be received in remote area of the entire building in acceptance performance.