I agree with Gum's recommendation.
Here are chimney antenna mounts.
www.ronard.com/ychim.html
Meausre around the chimney and use a ,
ronard(2212) , ronard(2218) , ronard(2224) .
Buy the ronard antenna mounts at ,
www.solidsignal.com or buy from ,
www.ronard.com .
Here are some places to buy antennas and etc. .
www.solidsignal.com
www.amazon.com
www.ronard.com