The difference between can and home antennas.
A SiriusXM Radio car antenna is magnetic and is required to be on a metal surface to get optimal signal. The antenna being on metal creates a ground plane around the antenna several inches in diameter.
A SiriusXM Radio home antenna is ground plane independent and are is required to be on a metal surface. Typically home antennas are directional and are required to face to the southern sky to get signal.