Antenna design Q

Hi all,
Although this isnt wireless networking related, im looking into
wireless CCTV links which are 2.4Ghz also so i guess you lot might
know...

I've bough a relatively cheap camera system with a wandering thought
of using it to film onboard action on a model boat. Problem is the
model boat could be far further away than the 200m range specified by
the camera specs, and it needs to be omnidirectional of course. Can
anyone point me at the best type of antenna to attempt to build to
increase my receivers range abilities - or at an amplifier - so that i
can get 500m, or at least a decent increase.

Does http://www.amsterdamwireless.net/workshop-15-12/3.html look like
a suitable option?? What sort of gain in range can i hope to acheive
with one of those, over the stock 'wireless pc card' type of antenna
it has now?

Cheers for any advice. Feel free to stone me if im asking too much
lol.
J


CoyoteBoy