Patent ID: 7259725

Claim:
A log-periodic dipole array antenna, including: a dielectric substrate, having a first surface and a corresponding second surface; a first symmetrical microstrip line, disposed on the first surface; a plurality of antenna elements, disposed on the first surface and connected to at least one side of the first symmetrical microstrip line, wherein at least one of the first antenna elements has a gradually increasing width outwards from the side of the antenna element, which is connected to the first symmetrical microstrip line; a first balun, disposed on the first surface and connected to one end of the first symmetrical microstrip lines; a second symmetrical microstrip line, disposed on the second surface; a plurality of second antenna elements, disposed on the second surface and connected to at least one side of the second symmetrical microstrip line, wherein the positions of the first antenna elements and the second antenna elements on the dielectric substrate are in a mirror-image relation, and the width of at least one of the second antenna elements is broadened gradually outwards from the side of the antenna element, which is connected to the second symmetrical microstrip line; and a second balun, disposed on the second surface and connected to one end of the second symmetrical microstrip lines.