How to implement FM antenna for portable system?

[martingn]

pcb fm antenna

Hi all,

I would like to implement FM radio chip with TEA5757 for a portable system with a fixed base charger.
My question is regarding how to implement the antenna.

Is it possible to use an inside-the-device antenna? I mean, no external wires.
Is it possible to integrate the inside antenna with and external one in the fixed base?

best regards,

Martin

 

[flatulent]

fm pcb antenna

If you are going to receive high power signals it is acceptable to use a low efficiency antenna such as one much smaller than a wavelength inside a plastic housing.

If the housing is metal you can use a slot antenna.

Experimentally determine your case by wiring up a prototype on a board and try different lengths of wire for the antenna either straight or bend around what would be the perimeter of the dimensions of the box you plan to use.

 

[martingn]

FM antenna

Thanks flatulent !
The case is going to be a plastic one.
Should the wire be always a length multiple of a wavelength? Any suggestions? Mininun lenght? Isit posible to make it on pcb?? Is there any article to read about pcb antenna for fm broadcasting range (88-108 mhz) ?

thanks in advance,
regards,
Martin

 

[flatulent]

Re: FM antenna

On receiving the length and impedance do not cause any damage to the receiver like they do to a transmitter if they are different than the design value. Therefore the exact length does not matter much.

The antenna should be far away from the ground plane of the circuit board, but again if you are receiving local broadcast stations you will have adequate signals no matter what routing you do for the antenna.