A dual-frequency L-shaped patch antenna

A novel design of an L-shaped patch antenna for dual-frequency operation is proposed. The proposed antenna is obtained by bending a planar rectangular patch into an L-shaped patch, which is then placed on a grounded substrate, with the patch's horizontal portion parallel to and above the substrate and the edge of the patch's vertical portion in contact with the substrate. The proposed antenna is fed by a 50 Ohm microstrip line printed on the same substrate, and the antenna's first two resonant frequencies can be excited with good impedance matching, and have the same polarization planes. Good broadside radiation characteristics for the two resonant frequencies are also obtained, and by inserting a pair of slits at the nonradiating edges of the patch's vertical portion, the frequency ratio between the two resonant frequencies can be varied, resulting in a dual-frequency operation having a tunable frequency ratio of about 1.66-1.94. (C) 2000 John Wiley & Sons, Inc.