Why wireless sensors fail in old stone or brick gallery walls

Diagram of layered security around an artwork: perimeter, building shell, interior zone, display or store, and the object

I was out at a converted bank building on Mostyn Street in Castlemaine a few months back, bluestone walls close to 600mm thick in places, and the gallery owner was showing me a battery report from her existing wireless system. Three sensors had dropped comms in the previous fortnight, all in the same back room. […]