What's the use of headphones for FM radio in mobile phones?

[rednewguy]

do the cel phones have separate antenna for fm radio.

wat is the necessity of headset in it. without connecting headset radio does not work. what purpose does headset serve.

thanks

 

[throwaway18]

mobile radio

I have no idea about cellphones with FM radio but portable FM receivers usually use the headphone cable as the antenna.

 

[js]

Re: mobile radio

cellphones also use the headphone cable as the antenna

 

[mohammad.r]

Re: mobile radio

the TX/RX built in antenna of the mobile phone is designed to operate at the frequency range of the mobile radio standards of the air interface(GSM/UMTS).
So,to recieve commercial FM broadcasting,the head set it self will serve as dipole antenna at the range of ~100MHZ.

 

[sachinlan]

Re: mobile radio

Yes. Cellphones have separate antenna for FM Radio. This is because FM radio needs a receiver of a frequecy band of ~ 90-120 MHz. That is why separate antenna is required.

You have to attach headset to a mobile to make FM work. Actually, when attached FM headset does a short circuit in the mobile and completes an electrical path which is necessary to make it work. When you remove the headset the circuit becomes open and doesn't work.

 

[mobile-it]

Re: mobile radio

This is correct; Mobile phones are using seperate FM anteness or use the headset as an antenna.

This is indeed because the frequencies are too far away from eachother.

It is already difficult to implement a 1900, 1800, 900 MHz antenna....

 

[azaz104]

Re: mobile radio

to achieve a good antenna gain at low requencies, you need to use a longer antenna because antenna gain is inversely relarted to "lambda", so they use the headphones themselves as this "long" antenna

 

[RobertGarcia]

Re: mobile radio

Yes, cellphones have separate anttenna for fm radio. Have you noticed that there are some cellphones need to attach the headphones first before accessing to the FM radio applications? In that case, the headphones are reliable of connecting your signal from cellphone to FM station. Cellphones and FM radio have different paths so they need separate antennas to connect from their band.

 

[keith1200rs]

Re: mobile radio

Robert,

You seem to be rather pointlessly digging up some very old threads.

Keith