Suppressing higher-order modes up to sixth harmonics of the fundamental working frequency in a single-layer microstrip line-fed patch antenna has been successfully demonstrated. Higher-order modes of the antenna are suppressed by simultaneously employing a circular head open stub connected to the feed line and a novel defected ground structure (DGS) beneath the feed line. The filtering property of the antenna has been improved by the novel DGS significantly. The role played by the novel DGS is carefully analyzed, and the effect of some key parameters of DGS is further discussed. A microstrip patch antenna with the working frequency 3.13 GHz (f_c) is designed and manufactured. The designed antenna possesses an ultrawideband harmonic suppression capability ranging from 2f_c to 6f_c. More importantly, the area occupied by the novel DGS is decreased by 41% compared to the earlier design.

中文翻译：

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微带贴片天线中新型变形地面结构的超宽带谐波抑制

已经成功地证明了在单层微带线馈电贴片天线中抑制高达基本工作频率的六次谐波的高阶模。通过同时使用连接到馈线的圆头开口短线和馈线下方的新型缺陷接地结构（DGS），可以抑制天线的高阶模。新型DGS大大改善了天线的滤波特性。仔细分析了新型DGS的作用，并进一步讨论了DGS某些关键参数的作用。设计并制造了工作频率为3.13 GHz（f _c）的微带贴片天线。设计的天线具有2 f _c的超宽带谐波抑制能力至6 f _c。更重要的是，与早期设计相比，新型DGS所占面积减少了41％。