An antenna module includes a substrate; a ground element disposed on the substrate; a first antenna element disposed on the substrate; and a second antenna element disposed on the substrate. The first antenna element and the second antenna element are, respectively, capable of transmitting radio waves having a first polarization direction and a second polarization direction unparallel to each other. A spacing between a perimeter of the ground element and the first antenna element increases as a function of increasing distance from the second antenna element. A spacing between the perimeter of the ground element and the second antenna element increases as a function of increasing distance from the first antenna element.