Homemade Antenna Signal Pre Amp How Can I Get More Cell Phone Signal Inside My Room Without Buying Anything?

How can i get more cell phone signal inside my room without buying anything? - homemade antenna signal pre amp

I want more signals from cell phones in my room without buying anything ... I want a notion of home as an antenna ... How can I do? ... Please reply or watever the **** bcuz I want to buy anything, but I want to do something to make the sign of home .. Please help