Dual-mode antenna for satellite/terrestrial communications

The increasing interest in the deployment of satellite constellations for personal communications has motivated the study of handset-mounted dual-mode antennas capable of operating in terrestrial- and satellite-based systems. These antennas must remain compact for handset operation, resonate at the proper frequencies, and provide the proper polarization (circular for satellite and linear for terrestrial operation). Additionally, in order to fully understand the antenna performance, it is necessary to predict the effect of the operator´s human tissue on the antenna radiation characteristics. This paper presents a dual-mode antenna consisting of a circularly polarized (CP) microstrip patch element and a linearly polarized (LP) planar inverted-F antenna (PIFA). The CP microstrip patch operates at the satellite up-link (1610 to 1626.5 MHz) and down-link (2483.5 to 2500 MHz) bands and the LP PIFA operates at the terrestrial band (902 to 928 MHz). The finite-difference time-domain technique (FDTD) is used to simulate the antenna with and without the presence of biological tissue. The influence of deploying the antenna away from the tissue is also discussed and simulation results show the improvement in performance obtainable using this strategy.