Computational imaging with low-order OAM beams at microwave frequencies

Kang Liu,Yongqiang Cheng,Hongyan Liu,Hongqiang Wang

doi:10.1038/s41598-020-68586-y

Kang Liu, Yongqiang Cheng + Show 2 more

Open Access

https://doi.org/10.1038/s41598-020-68586-y

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Journal: Scientific Reports	Publication Date: Jul 15, 2020
Citations: 13	License type: open-access

Affiliation: National University of Defense Technology

Abstract

With the distinguished wavefront characteristics of vortex electromagnetic wave carrying orbital angular momentum (OAM), the OAM beams have been exploited for radar imaging in recent years. In this paper, the computational imaging model is built using OAM wave, which enables the target reconstruction with limited measurements. The measurement matrix is designed, and the target reconstruction method is proposed in the Cartesian coordinate. Simulation results indicate that the proposed computational imaging approach is robust against noise influence. Furthermore, the outdoor experiments are carried out, for the first time, to validate the super-resolution imaging ability of this novel technique. Experimental results show good agreement with theoretical analyses. This work can advance the development of OAM-based sensing technology.

Highlights

With the distinguished wavefront characteristics of vortex electromagnetic wave carrying orbital angular momentum (OAM), the OAM beams have been exploited for radar imaging in recent years
The computational imaging technique has been widely applied at microwave frequencies to reconstruct the target[18,19], which can considerably reduce the set of measurements
S(t, l) = u(t − dTr ) ei2π(f0+d f )t · eilφn d=0 n=1 where u(t − dTr) denotes the rectangular pulse function, and Tr is the pulse repetition interval. f0 is the signal frequency of the first pulse, and f is the step frequency. φn indicates the azimuthal position of the nth antenna, D is the number of pulses, and N is the number of antennas. l denotes the OAM index

Summary

Introduction

With the distinguished wavefront characteristics of vortex electromagnetic wave carrying orbital angular momentum (OAM), the OAM beams have been exploited for radar imaging in recent years. The computational imaging model is built using OAM wave, which enables the target reconstruction with limited measurements. For OAM-based target imaging, the antenna array was most often used due to that multiple OAM modes can be generated simultaneously. The computational imaging technique has been widely applied at microwave frequencies to reconstruct the target[18,19], which can considerably reduce the set of measurements. The microwave computational imaging method is developed to achieve high-resolution target profiles with low-order OAM beams, in this paper. To the best of the authors’ knowledge, there are no publications reporting the outdoor experiments about OAM-based target imaging

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