If the building the Tv is located in is wood frame with wood or vinal/plastic siding and the building does not have a metal roof then a Simple Non Amplified indoor tv antenna will receive the channels in green.
http://forum.tvfool.com/showthread.php?t=233 , Here is inflammation of aiming Tv antennas , aim the antenna at about 30 degrees magnetic compass ,
http://www.kyes.com/antenna/pointing/pointing.html , Read and understand this about , Real Digital Tv Channels Virtual Digital Tv Channels , Analog Tv Channels ,
http://forum.tvfool.com/showthread.php?t=695. . If you will like to install a outside roof top Tv antenna then a ANT751 or simalar Simple VHF/UHF antenna.