A Radiospurs Tool Site
All have seen the famous helix antennae arrays used on the first human moon landing. An appropiate use for a travelling wave antenna. Here we deal with some aspects of helix antenna design for VHF, UHF up to S Band.
As usual all results: AS IS, no responsibility assumed.
A Simple Helical Antenna
An Axial Mode Helix
Also called an end fire Helix. An eminently practical version of the helix antenna. There is single major lobe with maximum radiation intensity along the helix axis. The minor radiation lobes are at oblique angles to the axis.
A Hansen-Woodyard Helix
Also called an end fire Helix. Like the axial mode helix but with a narrower beam, ofgset by larger side lobes.
A Hansen-Woodyard Helix
Also called an end fire Helix. Like the axial mode helix but with a narrower beam, ofgset by larger side lobes.
The "normal" mode requires strict shape control in order to keep the circular polarisation and normal to the boom.