How to Make Sprinkler Controller Control Valve Wirelessly

I am trying to design and build a remote switch system for my sprinkler system. I need to use the sprinkler controller (12v output for on) to trigger a transmitter to switch a 12v operated valve on the other side of the yard (about 300m away.) I have mains power at both locations but the underground 12v wire from the controller has been damaged so I would like to build a remote system to save putting new conduit for around 300m across the yard.

Looking at your systems, the easy part would be the receiver end because I would only need a 12v power supply. The hard part will be getting the transmitter to switch on when the sprinkler controller switches on (12v).

We recommend you direct power output high power long range remote control kit (S1PX-DC12-ANT2+CB-2V). The remarkable feature of this kit is that its transmitter is triggered DC power 5~28V input. That is to say, the transmitter will send out RF signal to receiver as long as it gets a 5~28V voltage from a device. Besides this advantage, its working distance is up to 2000m (6000ft). And the working current is 30amp. RF signal can pass through doors, walls and other obstacles.