Patent ID: 9001000
Filing Date: 2015-04-07
Classification: H01Q

Abstract:
1. An antenna comprising: a circuit board having a ground pattern; a first antenna element that is made of a conductive metal and that has a first branch element and a second branch element having a shorter electrical length than that of the first branch element; and a second antenna element that is made of a conductive metal and that has a third branch element and a fourth branch element having a shorter electrical length than that of the third branch element; wherein the first antenna element and the second antenna element are placed in proximity to each other while spaced apart from the ground pattern of the circuit board at a predetermined interval and are electrically connected to a first power feeding part and a second power feeding part placed on the circuit board, by a first matching part and a second matching part; wherein the antenna has a low coupling circuit that electrically connects a portion of the first antenna element to a portion of the second antenna element, the first matching part to the second matching part, or the first power feeding part to the second power feeding part and that conforms to a plurality of desired frequencies; wherein, when the plurality of desired frequencies are taken as a first frequency, a second frequency, and a third frequency in ascending order from a low frequency to a higher frequency, the first antenna element and the second antenna element exhibit resonance of a Y12 component of an admittance matrix between the first frequency and the second frequency and between the second frequency and the third frequency; wherein the first branch element and the third branch element assume a value of nearly a quarter of a resonant electrical length of the Y12 component of the admittance matrix between the first frequency and the second frequency; and wherein the second branch element and the fourth branch element assume a value of nearly a quarter of a resonant electrical length of the Y12 component of the admittance matrix between the second frequency and the third frequency.