Backward Scattering of Electrically Large Standard Objects Illuminated by OAM Beams
Kang Liu, Hongyan Liu, Wei E. I. Sha, Yongqiang Cheng, Hongqiang Wang
Abstract
To evaluate the interaction between the orbital angular momentum (OAM) beams and the electrically large standard objects, the backward scattering characteristics of the perfect electrical conductor (PEC) sphere and PEC cone are studied. First, the incident vortex electromagnetic field carrying OAM is generated by Hertizian dipole arrays. Subsequently, the backward-scattered field is calculated by the physical optics algorithm. The phase profiles and OAM spectra are analyzed in detail, which indicates that the scattered field for axial symmetric objects still keeps the main characters of the vortex field due to the angular momentum conservation. Finally, the radar cross section for PEC sphere and cone are calculated, respectively. The backward scattering features show significant differences when OAM beams change their topological charges. Consequently, given a specific propagation direction, compared to plane waves, more information will be offered by the OAM beams for object detection and recognition.