Need to trigger A reed Relay with nearby RF

[cobra149]

Hi,
can any one help , I want to build a pcb with a reed relay that will trigger on any
transmitted RF signal  (front end protection in mind ).
Hope this is possible, rather than using 12v tx on rear of radio to trigger the relay.
This way it would be more portable to connect to any second receiver using 9v battery.

So what would I need to ad to the circuit in front of the relay to detect the RF , that will switch the relay ?.

Thanks.