It is shown that the grating lobes issue of periodic leaky-wave antennas (P-LWAs) can be mitigated using parasitic monopoles placed between the antenna's unit cells. Due to the periodicity nature of P-LWAs, infinite number of space harmonics are excited, but only one space harmonic should radiate to achieve single-beam radiation. As the beam scans to the forward direction, a second space harmonic starts to radiate creating a double beam, a main beam and a grating lobe in opposite directions. Here, we present a simple and low-cost technique to overcome the grating-lobe issue in series-fed patch (SFP) P-LWA by inserting parasitic monopoles at each unit cell to reduce its radiation in the grating lobe direction, while maintaining the main beam. Moreover, the concept of parasitic monopoles and their effect on the radiation pattern of the unit cell is addressed and later validated by full-wave simulation and measurement results for an SFP P-LWA broadside frequency at 6.1 GHz. The results show that the grating lobes are reduced by about 10 dB and therefore, the scanning range is extended in the forward direction from 15° for the conventional SFP P-LWA to 29° for the proposed SFP P-LWA with parasitic monopoles.

中文翻译：

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使用寄生单极子在串联馈电贴片周期漏波天线中减轻栅瓣

结果表明，可以使用放置在天线单位单元之间的寄生单极子来缓解周期性漏波天线 (P-LWA) 的栅瓣问题。由于 P-LWA 的周期性，可以激发无限数量的空间谐波，但只有一个空间谐波应该辐射才能实现单光束辐射。当光束向前扫描时，二次空间谐波开始辐射，在相反方向产生双光束、主光束和栅瓣。在这里，我们提出了一种简单且低成本的技术，通过在每个单位单元中插入寄生单极子以减少其在栅瓣方向的辐射，同时保持栅瓣方向的辐射，从而克服串联馈电贴片 (SFP) P-LWA 中的栅瓣问题。主梁。而且，寄生单极子的概念及其对单位单元辐射图的影响得到了解决，后来通过全波模拟和 6.1 GHz SFP P-LWA 宽边频率的测量结果进行了验证。结果表明，栅瓣减少了约 10 dB，因此，正向扫描范围从传统 SFP P-LWA 的 15°扩展到具有寄生单极子的 SFP P-LWA 的 29°。