背瓣 meaning in English
episternites
Examples
- A patch antenna with air holes in the substrate has been designed . the finite - difference time - domain ( fdtd ) method together with the perfectly matched layer ( pml ) boundary treatment has been used to study the performance of the antenna . it is shown that the surface waves are significiently suppressed , the frequency bandwidth is improved , the sidelobe levels are reduced and consequently the gain in the forward direction is improved by 14 db ( about 4 db higher than the value reported previously )
设计了一种基底钻周期圆孔结构的电磁(光子)晶体贴片天线，用fdtd方法并结合pml吸收边界条件对该天线进行了研究，结果表明本文所设计的基底钻孔型电磁晶体贴片天线取得了多方面的性能改善，与普通天线相比，基底中的表面波受到很大抑制，天线的带宽增加，远场方向图上天线的旁瓣和背瓣被明显削弱，向前辐射的增益由原来的12db增加到26db ，增加了14db ，比文献上报道的gonzalo等人的研究结果提高了4db 。 - The radiation pattern of the antenna is more rotationally symmetric , and a more reduction on the sidelobe levels of the antenna is achieved as compared to the antenna with the corrugated soft surface . in conclusion , in the present thesis both theoretical and experimental research works have been carried out intensively on patch antennas based on photonic - bandgap structures . it is shown that our photonic bandgap structures can greatly improve the performance of the patch antennas
该平面圆环结构软表面天线是在空气介质的皱褶圆环结构软表面天线的基础上改进得到，为了便于比较，我们首先研究了空气介质的皱褶圆环结构软表面天线，用fdtd方法并结合pml吸收边界条件对该天线的性能进行了研究，结果表明天线的带宽增加，天线的轴对称性得到了很大改善， e面和h面方向图的波束几乎重合，天线的旁瓣和背瓣受到很大的抑制。