I switched my iPhone 8 into airplane mode, but it continued periodically transmitting on 1.8 GHz, as measured by an electrosmog meter. Why? Isn't airplane mode supposed to turn off the radio transmitters? Or is airplane mode on an iPhone only a low-power mode?
After enabling airplane mode, I powered the phone off and booted it in a Faraday cage. It still transmitted on 1.8 GHz, despite not being able to receive any cell tower signals.