Patent ID: 8723745

Claim:
An antenna apparatus having first and second feed ports respectively provided at predetermined locations on an antenna element, wherein the antenna element is simultaneously excited through the first and second feed ports so as to simultaneously operate as first and second antenna portions respectively associated with the first and second feed ports, wherein the antenna element is excited at one of a first frequency and a second frequency higher than the first frequency, and wherein the antenna apparatus comprises: an electromagnetic coupling adjuster provided between the first and second feed ports, the electromagnetic coupling adjuster providing isolation between the first and second feed ports at each of the first and second frequencies; a trap circuit provided on the electromagnetic coupling adjuster, the trap circuit that allows the electromagnetic coupling adjuster to provide the isolation at the first frequency when the antenna element is excited at the first frequency, and allows the electromagnetic coupling adjuster to provide the isolation at the second frequency when the antenna element is excited at the second frequency; and a first resonance frequency adjuster provided on the electromagnetic coupling adjuster, the first resonance frequency adjuster shifting a frequency at which the electromagnetic coupling adjuster provides isolation between the first and second feed ports, to the first frequency, when the antenna element is excited at the first frequency.