Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

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

Status
Not open for further replies.

rednewguy

Full Member level 2
Joined
Jun 3, 2005
Messages
123
Helped
2
Reputation
4
Reaction score
0
Trophy points
1,296
Activity points
2,413
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

Advanced Member level 2
Joined
Jun 9, 2005
Messages
596
Helped
101
Reputation
202
Reaction score
24
Trophy points
1,298
Location
Kent, UK
Activity points
8,365
mobile radio

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

js

Full Member level 5
Joined
Oct 9, 2005
Messages
265
Helped
38
Reputation
76
Reaction score
36
Trophy points
1,308
Activity points
2,662
Re: mobile radio

cellphones also use the headphone cable as the antenna
 

mohammad.r

Newbie level 4
Joined
Oct 31, 2005
Messages
7
Helped
1
Reputation
2
Reaction score
0
Trophy points
1,281
Location
JORDAN
Activity points
1,368
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

Banned
Joined
May 13, 2005
Messages
32
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,288
Activity points
0
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

Advanced Member level 1
Joined
Apr 24, 2004
Messages
467
Helped
22
Reputation
44
Reaction score
8
Trophy points
1,298
Activity points
3,352
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

Member level 5
Joined
Aug 30, 2005
Messages
85
Helped
14
Reputation
28
Reaction score
11
Trophy points
1,288
Location
Ottawa, Ontario, Canada
Activity points
2,453
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

Newbie level 2
Joined
Jan 21, 2011
Messages
2
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Location
New York
Activity points
1,291
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

Super Moderator
Staff member
Joined
Oct 9, 2009
Messages
10,877
Helped
2,064
Reputation
4,128
Reaction score
1,597
Trophy points
1,403
Location
Yorkshire, UK
Activity points
57,276
Re: mobile radio

Robert,

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

Keith
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top