超高斯波束圆口径天线近场辐射特性

Near-field radiation behaviors of super-Gaussian circular aperture antenna

采用口径场理论分析了不同孔束比(孔径与束腰之比)的超高斯分布圆形口径天线近场辐射特性,得到了聚焦条件下焦点位置的近场增益解析式。并对不同观测位置点天线的辐射特性进行了仿真,结果表明:当观测点小于焦距的0.3倍时,且波束阶数大于4时,天线的辐射图样与孔束比无关;当观测点位于焦点时,设定孔束比,不同阶数的波束分布的辐射图样明显不同,但当孔束比为4以上时,辐射图样基本保持稳定,而且高阶波束没有旁瓣出现。

Based on the aperture field theory, near-field radiation behaviors of supeFGaussian circular aperture antenna are discussed, and the near-field gain expression at focusing point while focusing is obtained. Corresponding simulations are conducted by selecting different observing points of antenna. The results show that the radiation patterns keep invariant in spite of the ratio of aperture radius to beam waist（RAW）, when the distance between the observing point and antenna is less than 0.3 times the fo- cal length, and the super-Gaussian order is greater than 4. Once the observing point lies on the focus, for given RAW, the radia- tion patterns vary with the super-Gaussian order. However, when the RAW is over 4, the radiation patterns keep stable and no sidelobes exist for high-order beams.