RF board layout guidence

[dTest]

Hi all!

I'm going to build a tiny transmitter from an web page project. (in the commercial FM broadcast band)
Plan on all surface mount.
I've never done any RF stuff before, and I know its a bit picky (and full 'how to do right' is out of scope here)
But asking mainly pitfalls/mistakes to avoid and maybe some tips.

Since its all (99%) SMT, would making the backside of the board a ground plane be good? Bad? Indifferent?
Should I (and how to)  separate the preamp/oscillator section from the output end?

Obviously I'm no EE, just a hacker/hobbyist.
Using EagleCAD if that matters at all.

TIA

[tggzzz]

It is good that you realise you don't know what you are doing, and that you ask for help.

Be aware that in most jurisdictions, transmitting without a licence is a criminal offence. Unless you know what you are doing, you will probably cause interference to users on similar radio frequencies and on completely different radio frequencies. That is frowned upon, to the extent there are significant criminal penalities.

Your best course of action is either to use ready-made modules, or to learn how to transmit legally by asking your local ham radio society and by passing the exams necessary to get a licence.

You will also benefit from understanding the information in this forum's "RF, Microwave, HAM Radio" section https://www.eevblog.com/forum/rf-microwave/

[dTest]

I am a licensed HAM.  *Low power* xmit on the FM band is legal (ever use a MP3 player to car radio device?)

[tggzzz]

I am a licensed HAM.  *Low power* xmit on the FM band is legal (ever use a MP3 player to car radio device?)

OK. Given that you wrote "I've never done any RF stuff before" and ask basic questions about RF construction, I didn't think that would be the case.

Over here you can buy specific equipment that is licenced for use in the FM band, but that doesn't mean there is blanket permission to create arbitrary equipment in the FM band. Local laws apply, of course.