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I want to use several 2.4 Ghz transcievers (not sure which IC yet, either Atmel AT86RF*** or TI CC) in order to build a simultaneous multi-channel sniffer. The transciever output is differential. I am not interested in transmitting anything.

Is there any way I can use a single antenna shared for all the receivers? How would this affect the RX sensitivity/antenna impedance?

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You need a power divider. However, It will add loss to your receive chain. An ideal 1:2 divider will add 3dB loss, real high quality dividers have ~3.5dB loss, resistive 1:2 divider has 6dB loss.

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I'm not an RF pro, but these things usually rely on impedance matching. That means, your antenna and receiver module should have the same impedance - usually \$50\Omega\$. When you connect multiple things to your path, you put multiple parallel loads on your antenna. With two receivers, your amplitude halves, so you lose about 3dB of your antenna output. What's more, that creates stubs in your signal path, that are bad.

I'd suggest looking at some RF demultiplexers - provided that you don't need continuous monitoring of the spectrum by all of connected devices.

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  • \$\begingroup\$ Continuous monitoring is exactly what I need, switching demuxes are not an option. \$\endgroup\$ Commented Dec 9, 2014 at 13:02

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