一种纯介质结构的宽带反射阵天线单元特性分析

Feature Analysis on a Broadband Reflectarray Antenna Element Based on Pure Dielectric Structure

提出一种基于纯介质结构的宽带反射阵单元结构。首先通过改变介质基片的介电常数,研究了纯介质单元的移相特性,然后采用阻抗匹配层技术,获得了宽带范围内平坦的相移曲线。由于自然材料的介电常数难以连续变化,这里使用介质基片开孔结构,实现了等效的介电常数非均匀分布。目前主流的反射阵天线使用微带贴片作为阵列单元,它存在工作带宽窄、相移范围受限的问题。提出的纯介质单元则为宽带反射阵天线的设计提供了一种新思路。

A broadband reflectarray element based on pure dielectric structure is proposed. The phase shift property of pure dielectric element is first studied by varying the permittivity of dielectric substrate. Then the impedance matching technique is adopted to achieve flat phase shift curve in a broad frequency. Since the permittivity of a natural material is usually fixed,a perforated dielectric substrate is used to reach the inhomogeneous permittivity distribution in an effective way. Currently,micro-strip patches are frequently used to construct reflectarray antenna,which results in narrow bandwidth and limited phase shift range. The pure dielectric approach provides an alternative way for broadband reflectarray antenna design.