Metal structures

Metal in buildings - the impact on Induction Loops

The importance of designing Induction Loop systems to cope with losses due to metal structures within the fabric of buildings cannot be over-emphasised. It is absolutely critical to allow for signal loss caused by metal structures during the system planning phase of any installation. If this is not done, the installed loop system is most likely to suffer from a range of problems - insufficient signal strength, uneven signal strength - loud in places and inaudible in others, lack of high frequency detail / clarity or other problems. Metal loss problems can be overcome, but only by proper design and attention to detail.

The Ampetronic Support team can help you to assess and compensate for the metal structures in your application – contact us if you would like some assistance.

Principles

The magnetic field generated by an induction loop system, induces a current in any closed path of a metal structure placed in the vicinity of the induction loop. Further Information.

These induced currents tend to weaken the magnetic field and cause loss. This loss is dependant on the type and thickness of metal and its position in relation to the induction loop.

Examples of Metal Structures

• Reinforced concrete floors – often containing a mesh. Further information about reinforcing meshes.
• Lightweight floor construction with a (usually profiled) metal sheet under a thin reinforced concrete slab
• Metal floor tiles - System floors
• Suspended ceiling grid - 600mm x 600mm (2' x 2') or 1200mm x 600mm (4' x 2') metal grids with acoustic or metal tiles
• Foil backed plasterboard - Vapour barrier
• Girders, beams, constructional metalwork
• Metal cladding, walls and roofs
• Metal counters - Whole or part metal
• Metal box construction - Elevators / lifts