Design of an Electrically Small Circularly Polarized Spherical Folded Helix Antenna

An electrically small folded helix with an electrical size of $ka=0.29$ is designed for operation in the GPS L5 band. To reduce axial ratio, parasitic elements around the equator are included in the antenna. The proposed design achieves instantaneous coverage of the L5 band with VSWR < 3:1 and axial ratio below 3 dB over nearly the entire field-of-view. Fabrication considerations are also discussed.