A Miniaturized Omnidirectional Circularly Polarized Antenna Using Double Torsion Coil Feeding Structure

A miniaturized omni-directional circularly polarized (CP) antenna is proposed in this paper. The antenna consists of a pair of double torsion coils(DTC) and a patch antenna. The first and second halves of the DTC are winded in opposite directions to maintain the coupling magnetic current in a ring direction. It can significantly reduce the height and a very compact physical size is maintained, only being 0.42 λ
0
×0.42 λ
0
×0.052 λ
0
(λ
0
is the free-space wavelength at 1.575 GHz). Simulated results demonstrate that the antenna has a good impedance matching at 1.575 GHz, and generate an excellent omni-directional circularly polarized radiation around the target frequency.