There are two types of signals using over the air (terrestrial) broadcast, VHF and UHF. Most digital channels are broadcast using UHF. The two rods on the common indoor antenna shown below are used to receive VHF signals. The loop part of the antenna is used to receive UHF signals. The antenna receives the strongest signal when the antenna is perpendicular to the broadcast signal. Therefore, moving the antenna so the flat side is toward the signal will give you the best reception.
Since signal usually comes from different directions, your TV will only add channels with sufficient signal strength that your antenna is pointing to when you run auto-program.
To add the missing channels, refer to the FAQ, “How can I manually program additional digital channels to my TV if I have a rotary antenna?”
There are different grades of indoor antennas available. Ones with a built in amplifier will give the best results.