A patch antenna includes a grounding portion and a radiating portion. The radiating portion includes a first feeding point, a first grounding point, a second feeding point, and a second grounding point. The first feeding point is electrically connected to a first signal source. The first grounding point is electrically connected to the grounding portion. The second feeding point is electrically connected to a second signal source. The second grounding point electrically connected to the grounding portion. The line formed by connecting the first feeding point and the first grounding point is substantially perpendicular to the line formed by connecting the second feeding point and the second grounding point.