Router Reception

I have a Netgear DG834G v2 fitted to my home PC, which is a Pentium 3 operating on Windows 98SE, broadband.

The reception around the house is poor, but having had a look at the little stubby aerial on top of the router, the connection looks just like a standard co-axial aerial connection. Can I extend this to improve reception around the house with either a proprietary accessory, or with just an odd bit of aerial cable ?