Patent ID: 8228231

Claim:
An antenna unit comprising: a first antenna; a second antenna; and a changeover switch configured to switch between using the first antenna and using the second antenna for reception and/or transmission of prescribed polarized waves; a chassis having approximately rectangular shape in cross section when viewed from a prescribed direction, wherein a first orientation is an orientation in which a plane containing a first side of the approximately rectangular shape of the chassis is approximately perpendicular to the direction of gravity, a second orientation is an orientation in which a plane containing a second side orthogonal to the first side of the approximately rectangular shape of the chassis is approximately perpendicular to the direction of gravity; and the first antenna and the second antenna are situated facing in directions 90° apart from one another when viewed from the prescribed direction; and a contact sensor disposed on the first side surface, wherein when contact is detected the first antenna is selected and when contact is not detected the second antenna is selected; wherein the first antenna in the antenna unit is positioned facing in a direction such that sensitivity of the first antenna to the prescribed polarized waves is higher than that of the second antenna if the orientation of the antenna unit with respect to the direction of gravity is a first orientation; and the second antenna in the antenna unit is positioned facing in a direction such that the sensitivity of the second antenna to the prescribed polarized waves is higher than that of the first antenna if the orientation of the antenna unit with respect to the direction of gravity is a second orientation different from the first orientation, wherein if the orientation of the antenna unit with respect to the direction of gravity is the first orientation, the changeover switch performs switching so that reception and/or transmission of prescribed polarized waves takes place using the first antenna, or if the orientation of the antenna unit with respect to the direction of gravity is the second orientation, the changeover switch performs switching so that reception and/or transmission of prescribed polarized waves takes place using the second antenna.