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Aluminum Thickness Effect on WiFi Notes

Aluminum foil (0.01–0.03 mm) Strong reflection/blockage Commonly used in signal-blocking hacks and Faraday cages
1–2 mm sheet (e.g., siding, panels) Near-total blockage Reflects or absorbs nearly all WiFi frequencies
>5 mm (structural) Complete barrier Acts like a wall for WiFi, especially 2.4 GHz