Terrestrial mode quadrifilar helix antenna

Abstract—In this paper we present a modification to the QHA whereby a gap is introduced at the current minima points at the centre of the helical sections of the QHA. The linear and rotational movement between the two halves of the QHA against each other is optimised to get current distribution, so that when tilted 90◦, it generates omnidirectional radiation pattern required for land communications in addition to hemispherical radiation pattern for space mode which is obtainable in conventional configuration. This makes it possible to use the single antenna for both terrestrial and satellite communications. The simulated results are validated by experimental measurements. 1