FM ANTENNA FOR PORTABLE RADIOS

[rrodriguez]

HELLO,

I'm looking for a fm antenna. I need know how can I build it on a printed pcb.

Thank you in advance.

 

[Mr_Programmer]

It's hard (nearly impossible) to do that on the pcb, because of the wavelength. The best receiver performance you will have with a antenne with the length of lambda/2 or lambda/4. For your case a example: 88MHz = lambda/2 ~ 1.7m :-?
Many manufactors of RF IC's have some application notes with good background descriptions. As example www.RFM.com ... and many other also ... :wink:

 

[THE BORG]

you just need to use a 5/8 wave stub on pcb load it up and couple it to a tight coil pick up system from one sid on pcb to another
{this is a good stsem for tuning also}

use a gdo and tune it up
you can add loading coils

as for software
i agree

there is none to be had

but im shure it exists as ive seen many examples of pcb coils but no software

 

[rrodriguez]

Thank you for all, but i'll like to know how portable radio works, I think that the headphones's wire is used as an antenna. I don,t know how the connection is made.

 

[eirp]

Yes, you can use headphone's wire as a primitive antenna. Connection into receiver is made trough a small capacitor (~10-100pF) which has small resistance for HF and don't give the pass for audio. Antenna is made from wire's shielding. It's better than no antenna..

Better is to use lambda/4 wire antenna electrically extended by coil if you want to have it "small"

Eirp

 

[Rostfrei]

Hello folks :lol:

How do you electrically extend antenna ? I would like to know some theory on that subject. Where to look for it. Does anybody have any ebook on that subject ?

Thank you in advance.

Regards,