一种天顶零点填充的圆极化全向天线OA

To address the issue of zenith scanning blind spots in traditional helical antennas,a circularly polarized antenna with zenith null filling was proposed based on a hybrid radiation mechanism combining a normal-mode helix and an equivalent short dipole.To generate an omnidirectional circularly polarized radiation pattern,the normal-mode helix was adopted as the main radiating element.The equivalent short dipole,formed by a feeding slotline and an impedance transition section,was employed as an auxiliary radiator to produce an axially omnidirectional pattern.The two radiation components were synthesized to realize omnidirectional circularly polarized radiation with a filled zenith null.Measured results show that,from 1.48 GHz to 1.67 GHz,the proposed antenna has a voltage standing wave ratio below 2,a gain higher than 5 dBic,and an axial ratio less than 3 dB,corresponding to a relative bandwidth of 12％.Meanwhile,the relative gain in the zenith direction remains above-10 dBic.The proposed circularly polarized omnidirectional antenna exhibits excellent zenith null-filling performance.