Penetration

The ability of radio signals to pass through obstacles like walls, floors, and materials. Varies significantly by frequency and material: lower frequencies penetrate better but provide less positioning accuracy, concrete and metal severely attenuate signals. Understanding penetration characteristics is critical for RTLS design and anchor placement.

Ability of radio signals to pass through obstacles, critical factor affecting RTLS coverage and accuracy. Material penetration characteristics for RTLS frequencies: (1) Drywall/wood - minimal attenuation (2-3 dB loss), signals easily penetrate multiple walls. (2) Concrete - moderate attenuation (8-15 dB per 15cm wall), multiple walls significantly reduce signal. (3) Brick - similar to concrete (6-12 dB), common in older industrial buildings. (4) Metal - severe attenuation (20-50+ dB), effectively blocks signals, causes reflections. (5) Glass - minimal attenuation for regular glass (2-5 dB), significant for metallized/tinted glass (10-20+ dB). (6) Water - high attenuation (significant absorption), includes human bodies (~70% water, causing 6-10 dB loss). Frequency penetration relationship: lower frequencies penetrate better (433 MHz better than 2.4 GHz better than 6 GHz better than UWB ~6-8 GHz). However, lower frequencies also mean larger antennas and reduced positioning accuracy, so frequency selection involves tradeoffs. Coverage planning tools simulate penetration: inputting facility construction materials and equipment layouts, propagation models predict signal strength and coverage, though actual measurements often show 20-40% worse performance than models (due to undocumented obstacles, irregular geometries). Understanding penetration characteristics of different RTLS technologies helps technology selection: UWB moderate penetration (good through drywall, challenging through concrete/metal), BLE/Wi-Fi similar penetration to UWB (2.4 GHz frequency), lower-frequency RFID better penetration (433/868/915 MHz), and optical systems (IR, laser) zero penetration (requiring strict line-of-sight).

Penetration specifications rarely provided by vendors: manufacturers typically cite range in open environments, not real-world penetration performance.