Would like some input on what antenna I should pick. Currently I have an Airspy with a 800mhz Radio Shack mobile antenna attached. I'm currently monitoring two 800mhz P25 systems that are max 15-20 miles away. When monitoring, both systems cut in and out, with one doing it more than the other. Also I do live at the bottom of a hill, not sure if that matters. I would prefer a solution that is indoors, but if needed could set something up in backyard. Any suggestions would be appreciated.