Very compact quadrifilar helix antenna in VHF band with quasi hemispherical radiation pattern

In this communication, two very compact quadrifilar helix antennas were proposed in VHF band. Significant height reduction is achieved with performances similar to the reference antenna in both input matching and radiation patterns. The proposed designs were found through a ‘cut and try’ simulation process. We may be able to further improve the height reduction while keeping good performances by associating an optimization algorithm to the electromagnetic simulation tool.