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

FM ANTENNA FOR PORTABLE RADIOS

Status
Not open for further replies.

rrodriguez

Junior Member level 3
Joined
Apr 12, 2002
Messages
28
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
148
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

Full Member level 3
Joined
Feb 21, 2002
Messages
153
Helped
9
Reputation
18
Reaction score
5
Trophy points
1,298
Activity points
1,424
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:
 

T

THE BORG

Guest
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

Junior Member level 3
Joined
Apr 12, 2002
Messages
28
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
148
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

Advanced Member level 1
Joined
Dec 11, 2001
Messages
466
Helped
29
Reputation
56
Reaction score
19
Trophy points
1,298
Location
Phase center
Activity points
5,142
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

Member level 2
Joined
Sep 17, 2001
Messages
51
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Activity points
463
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,
 

Status
Not open for further replies.
Toggle Sidebar

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top