I don't expect that you believe what I am going to say, since whatever source I provide you'll find another source that will tell the opposite of what I say, and I don't expect that you believe the fact that I have a degree in Telecomunications Engineering, but still I'll give you my 2 cents.
Any piece of microelectronics can become an antenna, but 1) it would works only on specific frequencies (depending on the material used, dimensions and thickness), usually not those used by a cellphone and 2) can be easily shielded with proper materials, so it's not a big deal, really. What I mean is that any sensible equipment that MAY cause problems by turning into an antenna for mobile phone's frequencies, is already shielded for good.
Antennas do not work for
each and every frequency out there in the air: every antenna is built to receive a SPECIFIC set of frequencies. Is it a GPS antenna? It won't be disturbed by mobile phone frequencies. Is it a Digital TV antenna? it will receive DTV signals, not Radio FM ones. And so on.
Pilots and crews use radio signals to communicate with the ground during the lift-off and the landing, without any interference with the airplane's instruments at all. The only reason that brought nations to forbid the use of cellphones on airplanes was that back then, the knowledge of radio signals was not so deep and pilots feared that cellphones would "mess" with communications between the pilot and the ground. Specifically, the FCC commission in the USA (federal COMMUNICATION commission) wrote that "multiple radio sources might clog the communications with the ground".
Come to Europe, and you'll find dozens of flights that already allow you to use your mobile phone with no limits. And those planes didn't receive any "extensive shielding" or whatever... they simply had to undergo a series of tests which proved that using lots of mobile phones during their landing or lift-off didn't cause any problem (because government are made by people who do not have deep scientific knowledge, so they want "evidence" that it works).
As for EM background, x-ray, cosmic rays, and so on... we are blasted, everyday, by a HUGE amount of radio signals, you do not even have the idea. Yet, your television set works, your refrigerator does too, your car doesn't go "boom" and your train brakes safely when it reaches the station.
Also, if in my office we can let our largely unshielded PCs and servers work, while we keep our mobile phones nearby (and we even receive calls!) without noticing the slightest problem... you know, I think it's safe to say that mobile phone's radio signal do not interfer with electronics. We are 34 people, each one of us has a PC and a mobile phone.
Oh, and by "largely unshielded" I mean that the electronics are open, many of our oldest servers do not even have a case because they risk to overheat otherwise.
My 2 cent.
Everyone is free to disagree
