A naive application of Nyquist sampling theorem will say you have to sample at twice the frequency of whatever you're trying to reconstruct - so for 2.4Ghz you

A naive application of Nyquist sampling theorem will say you have to sample at twice the frequency of whatever you're trying to reconstruct - so for 2.4Ghz you need to sample at at least every 6.25cm. The reason why you can't just use the base frequency is cause... well, for example, imagine you have the worst luck ever, and only ever sampled the nodes of the standing wave - it would just look like no signal. In practice... I have no idea. RF is too much for me.