How can I get better service in my basement apartment. I have the cell booster already. There is spot on the unit for an antenna. What type of antenna works with the unit? The booster only get 1-2 green bars. Once I got 6, but don't know why it was good on that day. I've tried various places to see if I can improve the signal. The window unit gets poorer signal on the window than against the wall. To complicate matters, I am near an airport and there is usually signal fluctuations. Any help with this problem?