Normally it would require alternating currents to product electromagnetic waves. Yet as mobile phone is powered by batteries which only produces direct current, what type of mechanism/structure allows them to generate the electromagnetic waves,i.e. the signals to communicate?

  • $\begingroup$ an AC power supply would not produce the necessary frequencies either ... why are you singling out cell phones? ... what about garage door opener remote control and RF toy remote control? ... use google to discover how a transistor AM transmitter works $\endgroup$
    – jsotola
    Oct 16, 2021 at 1:30
  • 2
    $\begingroup$ Read up on oscillator; devices which produce oscillating voltages when supplied DC power. $\endgroup$
    – AJN
    Oct 16, 2021 at 2:23
  • $\begingroup$ If you redirect DC in different directions through something, it becomes AC through that thing. $\endgroup$
    – DKNguyen
    Oct 16, 2021 at 19:50

1 Answer 1


Your cell phone contains an oscillator. This is a circuit which when fed direct current converts it into ultrahigh frequency sine waves, which are then modulated by an encoded version of the audio signal from the phone's mic unit.


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