RF Remote Clone using NRF905
You can connect an external antenna to pin 8 on that module. Just use a piece of wire that is 17.3cm long. But since the range is that bad to start with, probably means it isn't tuned very well. I'd return it, or try fiddling with the pot at the back. Not sure why Sparkfun has these crap transceivers for sale. Transceivers without a crystal are very inaccurate in their frequency. 

If you only need to transmit, I'd suggest this products: https://www.sparkfun.com/products/10534
 . Those worked great for me, and are currently switching on the power sockets for my lights when it gets dark enough.