Patent ID: 8081128

Claim:
An antenna device resonating at two different resonance frequencies, comprising: a substrate having a ground conductor surface; and a surface-mounted antenna main body having a radiating electrode portion disposed above the ground conductor surface of the substrate and a feeding electrode portion extending from the radiating electrode portion and connected to a feeding unit; wherein at least one slit is provided in or near an area where a density of a current induced on the substrate through short-circuit electrodes of the antenna main body on the ground conductor surface and flowing during operation is highest, the at least one slit being arranged perpendicularly or substantially perpendicularly to a direction of the current; and the at least one slit includes a capacitive adjustment slit portion having an open end that is open at an outer edge of the ground conductor surface, and an inductive adjustment slit portion having a first end that is connected to an end of the capacitive adjustment slit portion that is opposite to the open end of the capacitive adjustment slit portion, and a second end that is closed.