The dedicated chips in phones with the radios could have extra functionality for other spectrum activated by a trigger, possibly received wireless signal. So, it's a concern to me.
I can't imagine that pulsed digital transmission on 10Ghz would not create noise in the lower harmonics bands at all. The meter also have a sound mode where you eg. can hear the ~8-10Khz modulation of the mobile ~700/900/1900/2100Mhz signal.
You can clearly hear the difference between different transmission types as DECT phones, Wifi, GSM/LTE, and EM noise in general(PC's/HDMI cables/USB3 HD docks)
My central room heater has a small CR battry powered computer (that I had forgot all about) that calculate the bill and transmit the results every 2 minutes on 2.4Ghz
it makes a tiny ~0.5 sec pulse on the display/audio, and I thought for an hour that I had a hidden transmitter in my apartment, since turning the mains fuse off had no effect.
I had to clear the room of all tech to track down the source, felt a bit stupid when I finally found it.
So going down this road has some up's and down's vs staying totally oblivious of ones electromagnetic environment.
I would recommend something like the 'Cornet ED78S RF Meter' to every technician with the tiniest amount of AU in circulation.
The reason I got it was because I have become electro-sensitive, and that's almost a death sentence in the modern city.
Those pictures of Stallman sitting on a mountain top and not a mobile phone mast in sight looked very appealing...
My phone LG-L80 99£ is GSM only, all else is off, apps downloaded on wired PC and installed via ADB interface.
Currently used as book reader for C++11 fourth edition and as Wikipadia offline reader(Kiwix) 12GB on SD card - music/mp4 player and the battery last for a week or more.
I feel I'm in control of my phone, don't know if that is justified or not?