Stephane,

Please see the application note on microstrip and antenna design
on the Linx Technologies website.  It has formula and description
of how to do just what you are asking for.

http://www.linxtechnologies.com


Craig

> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Stephane Favard
> Sent: December 3, 1998 9:24 AM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: RF modules, PIC 16F84, Rolling Code
>
>
> Hi,
>
> Can anyone tell what's the best layout for "on board" Emmitter RF
> antenna with
> a 0.8mm dielectric board. It's a 433 Mhz RF module but I don't
> know impedance
> (may be 75 ohms...). I heard that it's better to have a gnd plane
> side and the
> antenna on the other side...
>
>
> thanks..
>
> Stephane
>