Dual-band circularly-polarized square microstrip antenna

New designs of obtaining dual-band circular polarization (CP) radiation of a single-feed square microstrip antenna are proposed and experimentally stu died. The proposed single-feed dual-band CP designs are achieved by inserti ng four T-shaped slits at the patch edges or four Y-shaped slits at the pat ch corners of a square microstrip antenna. From experiments conducted, a pa tch size reduction as large as 36% for the proposed design, compared to a c onventional CP design without the inserted slits, has been obtained. Detail s of the design considerations of the proposed antennas are described, and experimental results of the obtained dual-band CP performances are presente d and discussed.