Patent ID: 7248226

Claim:
An antenna device comprising a radiation slot that is formed in a conductor member and includes: a main slot part that is extended straight and has a power feeder part in the vicinity of one end; and first and second branch slot parts that are extended straight on both sides of the main slot part that is interposed between the first and second branch slot parts, the first branch slot part being connected to another end of the main slot part opposing the one end and the second branch slot part being connected to the vicinity of the other end of the main slot part, wherein a plane of polarization of an electric wave radiated from the main slot part and the first branch slot part is orthogonal to a plane of polarization of an electric wave radiated from the main slot part and the second branch slot part, and a length and relative position of each slot part is set such that the two electric waves differ in phase by 90 degrees.