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When I place my phone (Samsung S9) under my monitor (MSI https://www.msi.com/Monitor/Optix-MAG322CQP) and that someone call me, the monitor turns off. (It's plug with a DP cable).

Does someone has an explanation about why this is happening ?

Thank you very much.

Edit: Tried the same config at my friend's place, it doesn't turn it off. I will try with an HDMI cable to see if it could be linked.

Mathias Osterhagen
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Cell phones have a surprisingly strong output, as much as 36 dBm / 4 watts RF out. The wavelength, from ~0.5 cm (5G high band) to ~32 cm is just right to be picked up by some random piece of wire in the monitor, be rectified by some (overloaded) transistor or diode, and cause something to happen. Placing my cell phone near powered speaker cables, even though shielded, produces beeps in the speaker when the phone periodically tries to contact a tower. BTW, the farther the cell tower, the higher the signal strength the phone uses.

As for damage, it's certainly possible, though hopefully hasn't happened yet. In the future, keep the phone away from sensitive devices.

DrMoishe Pippik
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  • They don't seem as bad as they used to be near audio gear. Back in the 90s there was a clear 'phones off' rule in most recording studios, because of the constant 'hunting' they would do - yet there was always one who forgot, so halfway through a take you'd start to hear that distinctive beep-bippedy-bip-bip & the take was ruined :\ – Tetsujin Jan 15 '23 at 08:49
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    @Tetsujin, thanks for that anecdote! BTW, wavelengths are steadily decreasing to enable higher data rates (though decreasing penetration through rain and shrubbery), and electronic devices are being made more compact, with shorter cables and circuit traces, so I'd suspect a slew of new problems arising with 5G... in addition to known radio altimeter issues. – DrMoishe Pippik Jan 15 '23 at 17:56
  • I tested again on the same monitor at a friend and it doesn't turn off. He is plug in HDMI and me in DP so I suppose it could be 1. The cable or 2. I have bad reception at my place so the phone force much more to get the signal ? what do you think @DrMoishePippik ? – Mathias Osterhagen Jan 20 '23 at 13:50
  • @MathiasOsterhagen, it could be as simple as the way the cable or internal wires are laid out -- they act as antennas, and are directional, to some extent. https://en.wikipedia.org/wiki/Random_wire_antenna – DrMoishe Pippik Jan 20 '23 at 18:44