一种具有低不圆度的宽带水平极化全向天线

A broadband horizontally-polarized omnidirectional antenna with small gain variation

针对传统小环形全向天线相对阻抗带宽小、不圆度高的问题,设计了一种具有低不圆度的宽带水平极化全向天线。此天线包括三个弧形电偶极子、三组引向器和一个宽带馈电网络。三个弧形电偶极子被均匀地印刷在圆筒形的介质板表面并由宽带馈电网络激励,实现水平全向辐射。电偶极子上方加入三组引向器,可扩展天线的带宽和降低天线的不圆度。一分三功分器与宽带巴伦构成了此天线的馈电网络,采用馈电网络与天线一体化的设计方法,使天线结构小型化。设计并加工了尺寸为0.18λ×0.18λ×0.18λ(λ表示最低工作频率对应的波长)的天线样品。测试结果显示,天线相对阻抗带宽可达到51.6%(2.3~3.9 GHz,VSWR<2),在工作频段内天线不圆度小于1.2 dB。

To overcome narrow impedance bandwidth and high gain variation of the conventional horizontally-polarized omnidirectional antenna,a new one was proposed with small gain variation.The new antenna was consisted of three curved dipoles,three groups of directors,and a broadband feeding network.The curved dipoles were printed uniformly on a compact dielectric cylinder and fed by a feeding network to achieve omnidirectional radiation with horizontal polarization.Directors were employed above the dipoles to widen the impedance bandwidth and reduce the gain variation of the proposed antenna.The feeding network was composed of a 1-to-3 power divider and three baluns.By integrating feeding network and antenna,the whole antenna can be miniaturized.The overall volume of the proposed antenna is only 0.18λ×0.18λ×0.18λ,where λ represents the wavelength of the lowest operating frequency.Measurement results show that the impedance bandwidth of the antenna is 51.6% with VSWR<2 from 2.3 GHz to 3.9 GHz.Furthermore,a small gain variation of less than 1.6 dB is observed over the entire operating band.