双频双端口天线的隔离度优化设计

Optimization Design of Isolation for a Dual-band Dual-port Antenna

设计了一款双频双端口微带阵列天线,该天线由两个矩形辐射贴片构成。将两个辐射贴片平行放置,在其中一个低频对应的较大尺寸贴片上开矩形槽,将高频对应的较小尺寸贴片嵌套在矩形槽中。相互嵌套的结构形式带来严重的端口耦合,而天线端口间的互耦是制约阵列天线性能的主要因素之一,在辐射贴片间加载两条平行微带线用来隔离耦合电流,并且在平行微带线中间设置圆形接地贴片,通过过孔将微带线上耦合电流引入地板,同时在高频辐射贴片嵌入部分的垂直边两侧开缝,能进一步有效减小耦合电流,提高隔离度。经过隔离度优化设计后,最终实现天线在工作频带内隔离度均大于20 d B。天线的工作频段分别为15.2 GHz(14.83~16.10 GHz)和5.8GHz(5.68~5.88 GHz),对应的最大增益分别为7.8 d Bi和6.8 d Bi。天线两个辐射贴片尺寸分别为0.36λ(15.2GHz)和0.37λ(5.8 GHz),该天线辐射单元相互嵌套,满足小型化设计需求。

This paper presents a dual-band dual-port microstrip array antenna which consists of two parallel rectangular patches. A rectangular slot is created on the larger size patch corresponding to the low frequency band,and the small patch corresponding to the high frequency is integrated into the slot. The nested structure brings serious coupling between two ports,and the mutual coupling is one of the main factors that affect the performance of array antenna. In order to improve the mutual coupling of the nested parts,two parallel microstrip lines connected by a grounded disk are loaded between the two radiation patches to reduce coupling current,and two slots located on the vertical edges of the nested small patch further reduce the coupling current to improve isolation. After the optimization design,the final isolation of the antenna in the working band is greater than 20 d B. The working bands of the proposed antenna are 15. 2 GHz and 5. 8 GHz,the maximum gains in two bands are 7. 8 d Bi and 6. 8 d Bi. The two patch sizes of the proposed antenna are respectively 0. 36λ（15. 2 GHz） and 0. 37λ（5. 8 GHz）,and the radiation patches are nested in each other which meet the requirements of miniaturization design.