Multifilar hemispherical helical antennas

This investigation examines the radiation characteristics of a new bifilar hemispherical helical antenna. Directivity, E- and H-plane radiation patterns, axial ratio and input impedance of a few example designs are calculated. It is shown that the bifilar hemispherical helix provides a nearly constant gain over the measured bandwidth of about 14% and generally elliptical polarization with near circular polarization in limited cases.