I'm thinking of mounting an outdoor antenna on my deck railing that is metal (I'm assuming it's aluminum). What will that do to my signal? Will it make it worse, better, or make no difference at all? The baluster is about 4 feet in height, and 10 feet long with metal bars every 4 inches or so. I don't know much about how antennas work but aren't UHF bay antennas essentially just big aluminum grids? I would assume it wouldn't have an adverse effect on my signal but I just wanted to ask someone that would know more about this issue. I live on the second floor of a three story condo so this is pretty much my only option other than an indoor antenna.

Probably not much, as long as the antenna is in front of the railing and not behind it. It will reflect some signal but that style antenna is pretty good at rejecting reflections from the back.