Hi Jinx,

I think that you can use two 433 MHz modules keyed with different codes
(simplest: two different frequencies) and a corresponding receiver. You
don't really need to make the radiation patterns entirely separate, just
detect when the two signals mix equally. The transmitter antennas will be
two rubber ducky antennas for 433 MHz spaced by lambda/4. Each will act as
the reflector for the other. I suggest ILS modulation pattern: One
transmitter sends 50% duty cycle and the other 20-30% in the gaps of the
first. This assumes that the receiver is peak-detecting. Watch out for
continuous beat from residual carrier (since you are using two
transmitters with different reference clocks).

Peter

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