Improved form of backfire bifilar helix conical beam antenna

The nonresonant-length backfire bifilar helix is often used as a vehicle satcom antenna, as it has a circularly polarized conical beam with azimuthal symmetry. Some antenna configurations, however, exhibit poor back-lobe levels. It is shown that radiation patterns can be significantly improved by correct termination of the helix. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 14:278–280, 1997.