Hi,
I have not done this, but here's some opinions. I think it will be impossible to retrieve full tridimensional position using only one transmitter and one receiver. You will have to use a system similar with GPS, but at a lower scale. Basically, GPS satelites are moving above the target, this is why complexe algorythm are required to obtain position. If you will use stationery transmitters, your work will be far easy. But you cannot do it, only with at least three transmitters. Basic principle of retrieving position by RF means is triangulation.
/pisoiu