Circularly Polarized Chip Antenna Design for GPS Reception on Handsets

A compact global positioning system (GPS) antenna applicable for mobile handsets is presented. The key geometric feature is the use of a parasitic coupled feed, which forms a parallel LC resonator on the antenna chip. It draws currents on the chip and nearby ground plane edges so that pattern and polarization properties can be manipulated with an extended antenna region. By setting up a phase difference and balancing the magnitudes of perpendicular currents, a circularly polarized reception pattern is generated. The moderately directive upward pattern is convenient for navigation uses. The proposed antenna exhibits not only a circularly polarized pattern, but also decent gain and good matching. GPS reception performance evaluation is conducted by calculating mean effective gain and interference rejection rate based on radiation patterns. The results confirm its superior performance. The optimal antenna location on the board is also found via this approach. The antenna is of simple structure, low profile, and requires no clearance region on the board. A planar configuration is also presented. This alternative design can be integrated within the system board and conveniently installed in extremely thin devices. Rigorous parametric studies were conducted to develop tuning measures useful in transporting the design to other platforms.