Patent ID: 7345637
Filing Date: 2008-03-18
Classification: H01Q

Abstract:
1. A radio device, comprising: a power supply circuit for generating a high-frequency signal corresponding to a transmission signal to be transmitted in a radio manner; a first antenna including a folded path having a start end connected to the power supply circuit at a feeding point and a frequency matching portion connected to the folded path for matching first and second frequencies each other, a length between the start end and a finish end corresponding to a half of a wavelength of the first frequency belonging to a use frequency band, the folded path being folded so that the finish end is grounded to a grounding point located at a distance equal to or shorter than a fifth of the wavelength of the first frequency from the feeding point, thereby having an outward path and a return path, one point in the outward path and one point in the return path being short-circuited at a short-circuit portion so that the folded path reaches the grounding point through the feeding point and the short-circuit portion; and a second antenna branching, from the first antenna, in a branch portion located between the feeding point in the outward path and the short-circuit portion, having an open end and having a portion from the feeding point in the outward path to the branch portion in common with the first antenna, a length from the feeding point to the open end through the branch portion corresponding to a quarter of a wavelength of the second frequency belonging to the use frequency band, wherein the folded path of the first antenna has a length corresponding to a half of the wavelength of the second frequency, or a value close thereto.