A multi-loop antenna system includes: a plurality of loop antennas disposed on a substrate and arranged such that each of extending lines extending respectively from geometric centers of the loop antennas to a center point that is bounded by the loop antennas has a predetermined length, and that each of the loop antennas is spaced apart from an adjacent one of the same by a predetermined distance; and a system module facing toward and being spaced apart from and parallel to the substrate such that the grounding plane is able to reflect radiation from the loop antennas. Each of the loop antennas includes first and second radiator portions operable in respective frequency bands; the former having opposite ends that respectively serve as signal-feed and grounding sections; the latter having opposite ends that are connected respectively to the signal-feed and grounding sections.