Fero wrote:
"what is the difference between RF-circuit board ( high frequency ) and
non-RF-circuit board ?
What happen when I use non-RF-circuit board for 900 MHz frequency ? "

It could be the dielectric substrate material of the board as Ralph
wrote, or it could also be just how the board is laid out. At least,
it's not quite clear to me from your question that it's strictly the
board material.

As for material, for low-power things at least, we generally don't
bother with expensive Duroid or Teflon or similar substrates out to
1GHz. We find that good FR-4 fiberglass-epoxy material will usually
work OK. One of the concerns that you should be aware of, though, is
that the dielectric constant of FR-4 is NOT as well controlled as the
dielectric constant of the better (and much more expensive) RF
substrates. Also, the dielectric constant for FR-4 is quite a bit
higher, leading to narrower traces and therefore higher loss, to
achieve the same transmission line impedances (or smaller pads to get
the same capacitance). So if you have a layout designed for some
particular dielectric constant and it uses transmission lines and/or
physical structures to do filtering or impedance matching, expect to
have to modify it to work properly if you use a different substrate
material. Obviously, it's also important to pay attention to the
dielectric thickness if you're trying to get particular microstrip
impedances.

The freeware "RFSim99" program has a tool for doing some simple
microstrip calcs, and you should be able to find web applets that cover
much more complicated cases like buried microstrip, stripline, balanced
microstrip, etc. You can also find free/student/trial programs that
analyze more complex structures, though all that may be going well
beyond what you're interested in.

Cheers,
Tom