I have a bunch of sensors that i want to use over RF. I have two way RF working well, but when i move the devices away from each other even a few feet they stop working. I have tried attaching wires for antennas. Is there special wire for antennas or do I need to do something special with the antennas?
You need an antenna, at the transmitter and the receivers.
I think 17.2 cm it should be, but you might have to experiment. And they should be straight and all point in the same direction (all horizontal or all vertical).
I had a small box, and I tried to get the best signal. I tried winding it like a coil or folding it to make it fit into the small box. In the end some winding and some bending was the best. But don't try that, use a straight antenna.
is it 435mhz or 433mhz?
anyway, for 433mhz a normal 17.3cm long copper wire should do the job.
and how many feet is "few"? 2/3 or 20/30? at 2/3 feet distance antenna quality should not be an issue.
so check other thing as well... like make sure you supplying enough watts. plus check for loose connection or moving parts when you move it!
Also any coils should not be messed with.