Replying to Internet Connection

 Hey all, so i just moved into a new house. the house has wireless internet and my desktop has an antenna. Problem is, I can pick up other signals outside of the house but there are sparse and low connectivity. The houses wireless signale in low to non existant in my room, but when my roomates try their laptops in my room, they get a full strength signal. I have no idea why they can pick up a full strength signal and i cant, yet i can pick up signals from other sources? any suggestions?