Zhang Chao, Chen Dong, Jiang Xuefeng
Labs of Avionics, School of Aerospace Engineering, Tsinghua University, Beijing, 100084, P. R. China.
Sci Rep. 2017 Nov 13;7(1):15412. doi: 10.1038/s41598-017-15250-7.
An electromagnetic (EM) wave with orbital angular momentum (OAM) has a helical wave front, which is different from that of the plane wave. The phase gradient can be found perpendicular to the direction of propagation and proportional to the number of OAM modes. Herein, we study the backscattering property of the EM wave with different OAM modes, i.e., the radar cross section (RCS) of the target is measured and evaluated with different OAM waves. As indicated by the experimental results, different OAM waves have the same RCS fluctuation for the simple target, e.g., a small metal ball as the target. However, for complicated targets, e.g., two transverse-deployed small metal balls, different RCSs can be identified from the same incident angle. This valuable fact helps to obtain RCS diversity, e.g., equal gain or selective combining of different OAM wave scattering. The majority of the targets are complicated targets or expanded targets; the RCS diversity can be utilized to detect a weak target traditionally measured by the plane wave, which is very helpful for anti-stealth radar to detect the traditional stealth target by increasing the RCS with OAM waves.
具有轨道角动量（OAM）的电磁波具有螺旋波前，这与平面波的波前不同。相位梯度可以在垂直于传播方向的方向上找到，并且与OAM模式的数量成正比。在此，我们研究具有不同OAM模式的电磁波的后向散射特性，即使用不同的OAM波测量并评估目标的雷达散射截面（RCS）。实验结果表明，对于简单目标，例如以小金属球作为目标，不同的OAM波具有相同的RCS波动。然而，对于复杂目标，例如两个横向布置的小金属球，在相同入射角下可以识别出不同的RCS。这一有价值的事实有助于获得RCS分集，例如不同OAM波散射的等增益或选择性合并。大多数目标是复杂目标或扩展目标；RCS分集可用于检测传统上由平面波测量的弱目标，这对于反隐身雷达通过使用OAM波增加RCS来检测传统隐身目标非常有帮助。
