You need an
amplifier/antenna distribution
unit and two directional antennas.
This won't be cheap.
Especially at 2.4 GHz, since Sabine is the ONLY manufacturer to venture into this territory. As I said, the main problem isn't so much the distance between receivers (a good receiver should be able to work over 1000 feet from the transmitter, assuming a low noise floor and no direct interference), but rather the other devices competing for spectrum space and raising the noise floor. Unfortunately, in today's world it's virtually impossible to lower the noise floor. The only thing you can do is shut down all 2.4 GHz devices you can control, and get the receivers as close to the mics as possible to increase the signal-to-noise ratio.*
It is worth noting that because this
system operates at 2.4 GHz, the usual trick of moving antennas closer to the transmitters by using long(er) runs of
coax cable is now a losing proposition. According to Sabine's own
manual, loss is 16dB at 10 meters for RG58 - that's huge. To get losses to a manageable
level (2.5 dB/10m), you'd need to use Belden 9913 or equivalent RG8/U cable, which will be very costly. I wouldn't recommend it.
*I realize this sounds contradictory, since I just said that distance isn't the problem. And it isn't. The main issue with this
system is simply that the noise floor is quite high in the 2.4 GHz band. Therefore, the receivers need to be closer to the transmitters in order to hear them.