UC San Diego

In this letter, a compact and robust dual circularly polarized patch antenna for combined Globalstar/GPS application has been presented. The designed patch antenna is accomplished with size of 40×40×6mm3 over the frequency bandwidth of 1570-1650 MHz, which is 0.21λ0× 0.21λ0× 0.03λ0 (λ0 is the free-space wavelength at the lowest frequency of the operating bandwidth). Instead of air substrate, high-permittivity substrate is adopted for the size reduction. The bandwidth reduction due to the inclusion of the high-permittivity substrate is compensated by introducing a parasitic patch. In addition, a 90° hybrid is utilized for achieving dual circular polarization. The designed antenna is validated by the measurement, presenting a 5% fractional bandwidth (1570-1650 MHz) for both VSWR < 2, axial ratio less than 3 dB, and port isolation less than -6dB.