Single-feed dual-frequency rectangular microstrip antenna with a pair of /spl pi/-shaped slots

The authors demonstrate that by embedding a pair of /spl pi/-shaped slots close to the non-radiating edges with a single probe feed located along a centerline of the rectangular patch, a new dual-frequency operation of the antenna can easily be obtained. The two operating frequencies of the proposed antenna are also found to have the same polarization planes and similar broadside radiation characteristics, and the frequency ratio of the two frequencies is obtained ranging from 1.03 to 1.19. This makes the proposed antenna more suitable for dual-frequency applications where a lower frequency ratio is required.