Off-hull radio frequency emissions from below-deck spaces in ships

Measurement results and model analyses are presented for off-hull RF emissions caused by intentional transmitters radiating at 2.4 GHz and 5.8 GHz in enclosed, reflective spaces typically found within ships and aircraft. These transmissions can originate from shipboard wireless local area networks, radio frequency identification (RFID) tags and readers, handheld radios, and telemetry sources. Reverberant below-deck spaces with direct access to open air through windows and hatches exhibit surprisingly large off-hull signals detectable at substantial distances from the ship or aircraft. This situation occurs for total radiated power from the (multiple) transmitters at levels as low as 10 – 25 mW inside the below-deck space.