Wifi router as repeater with antenna for receiving

Hi.
I have an old wifi router and I need to port my home wifi to the garage. The wifi arrives near it, and my intention is to put an antenna on the last wifi-covered place. That antenna is wire connected to my old router in my garage that repeats what the antenna is receiving in the garage.
How can I do that?
Thanks!

Can you explain a little more clearly what you are trying to do.
Some details of the wifi router would also help, but normally a wifi router wont work as a wifi repeater.
It normally acts as a bridge between the wifi port and the hard wired ports.

Hi

It depends on what router is the "old one",newer routers do support WIFI extender mode.
Very older ones didn't.
The Tenda Wifi Repeater are fairly cheap and work quiet well.
Alternatively get a lan cable and setup your "old" router as a "Access Point" enabling DCHP Relay or disable DHCP completely if you going to take DHCP from your existing internet.

Yes, in my intention my "old" router will be a repetitor running OpenWRT (current firmware is really too old to do anything). My question is, without moving the router but with just an antenna (connected with a wire to the router), I can get the wifi (that will be repeated) from a spot that does not reach my router-repeater.