If not it's usually a bad idea. Try one of these if it almost works now.
http://www.amazon.com/Etekcity-Wireless-Network-Adapter-Computer/dp/B006JWMOOI/ runs about what folk pay for antennas alone.
To start with I don't know much about all this stuff but I do know you have to be reasonably close to someone to pick up their wifi. I just moved here and my neighbor gave me permission to use his wifi. Even though we are reasonably close I can hardly pick up a signal. I have to go towards one end of his house . He is across the street from me. We are not directly across, his house is a little further down from mine but we still are across from each other my house ends in about the middle of his. Im sure that plenty close enough that I should be even picking up signal kn my house.. I can get his signal in my house at all. Every once in a blue moon it will pop up. Well in reading windows help they suggested the external antenna but I was a little confused if it will help me pick up his signal better and give more range to even pick up other signals or is more for people with the router and modems . . My question is will this device give me more range to pick up his signal better or other signals even. Or is there a way to get wifi other than going through a company cause I'm sure you have to get a router and all that and like I said j just moved and need my computer for job searches and such. Any kind if advice is welcomed. And I talked to someone that didn't know anythjng about the external antennas but he did suggest that I ask my neighbor to put and extender on the other end of the house. I don't think someone is gonna go buy an extender just so someone can connect to their wifi. Now if it's something fairly cheap maybe It something I could do as long as there is no labor involved for hjim or difficult to install Thank you