How much do concrete walls and steel structures cut the range?
The ~100 m (SF series) and ~150 m (ST series) figures given on the product pages are for open ground. Reinforced concrete walls, steel structures, stacked containers and metal racking both absorb and reflect the signal; in enclosed volumes the actual range falls markedly below the open-ground figure. No numerical reduction ratio can be declared.
When a radio signal meets an obstacle three things happen: part of it is absorbed, part is reflected and part is diffracted around the edge of the obstacle. The material determines these three shares.
- Reinforced concrete: the steel mesh inside it behaves like a grid; absorption is high.
- Steel structures, metal panel facades, stacked containers: largely reflect the signal. Reflections sometimes appear to increase the range, but signals arriving by different paths can also cancel each other — which is why the connection recovering after a few steps forward is a typical symptom.
- Drywall, timber, glass: relatively low attenuation.
- Materials containing water (wet timber, stacked product, dense crowds): pronounced absorption.
Giving a numerical "it drops by X%" statement is not correct; the result changes even between two points inside the same building. The practical approach is a site test: after installation, actually try the response at every point where the operator will work and improve the antenna placement according to the weakest point.
Order of improvement: move the antenna outside the panel and up high, position it vertically, separate it from large metal surfaces, and bring the receiver position closer to the centre of operations.
The full topic: 433 MHz or 2.4 GHz?