Patent ID: 8681053

Claim:
An antenna apparatus, comprising: a grounding antenna element having one end connected to a grounding conductor; a first antenna element formed to be substantially parallel to a peripheral edge portion of the grounding conductor, the first antenna element having one end connected to another end of the grounding antenna element; a feeding antenna element configured to connect a feeding point with a predetermined connection point on the first antenna element; a third antenna element having one end connected to another end of the first antenna element; and a second antenna element having one end connected to another end of the third antenna element, wherein a first coupling capacitance is formed between the second antenna element and the grounding antenna element by bending another end of the second antenna element to be adjacent to the grounding antenna element so that another end of the second antenna element is electromagnetically coupled to another end of the grounding antenna element, wherein a first length, from the feeding point via the feeding antenna element, a connection point on the first antenna element and the first antenna element, to another end of the first antenna element, is set to a length of a quarter wavelength of a first resonance frequency, so that a first radiating element having the first length resonates at the first resonance frequency, wherein a second length, from the feeding point via the feeding antenna element, a connection point on the first antenna element, the first antenna element, the third antenna element and the second antenna element, to another end of the second antenna element, is set to a length of a quarter wavelength of the second resonance frequency, so that a second radiating element having the second length resonates at the second resonance frequency, wherein a third length, from the feeding point via the feeding antenna element, a connection point on the first antenna element, the first antenna element, the third antenna element, the second antenna element and the first coupling capacitance, to the grounding antenna element, is set to a length which is one of a half wavelength and three-quarter wavelength of the first resonance frequency, so that a third radiating element having the third length and constituting a loop antenna resonates at the first resonance frequency, and wherein the first antenna element is formed so that a width from another end of the first antenna element to a connection point between the first antenna element and the feeding antenna element is gradually expanded in a shape of taper shape toward the connection point.