An Omni-directional Circularly Polarized Helical Antenna with an Inductive Feed.

The paper presents an omni-directional circularly polarized (CP) helical antenna with an inductive feeding structure. The antenna is comprised of a printed helix with six arms on a thin rolled substrate and a feeding loop, which acts as the radiator and the feeding structure, respectively. The helix is fed by the feeding loop without physical connection through inductive coupling, which is convenient to achieve impedance matching. The 90 phase difference between the radiated horizontal and vertical electric field components is naturally guaranteed by the helix; therefore, circular polarization is achieved through tuning the height and radius of the helix to ensure equal magnitude of the radiated horizontal and vertical field components. With an electrical size of 0.17λ₀ x 0.17λ₀ x 0.11λ₀, the antenna exhibits a simulated impedance bandwidth (|S11| ≤ -10 dB) of 5.72% and AR bandwidth (AR ≤ 3 dB) of 27.4%. [ABSTRACT FROM AUTHOR]