Study of the Extended Phase Shift Migration for Three-Dimensional MIMO-SAR Imaging in Terahertz Band

Hang Gao,Shen Zheng,Shiyou Wu,Chao Li,Guangyou Fang,Hebin Geng,Xiaodong Qu

doi:10.1109/access.2020.2965189

Abstract

In this paper, the extended phase shift migration (PSM) for three-dimensional (3-D) multi-input-multi-output synthetic aperture radar (MIMO-SAR) imaging in terahertz (THz) band was studied. Based on one-dimensional MIMO arrays combined with synthetic aperture scan along another dimension, MIMO-SAR imaging scheme allows the number of array elements to be greatly reduced compared with the two-dimensional (2-D) MIMO arrays. By analyzing the derived analytical expression of the scattered waves in the frequency-wavenumber domain, the MIMO-SAR data in a certain frequency is mapped to another frequency of the `explode fields' of the monostatic form in accordance with a newly defined 3-D dispersion relations. By multiplying the modified phase shift terms in each frequency of `explode fields', the `explode fields' at different range planes can be reconstructed. Finally, the `explode fields' at time t = 0 can be successfully derived to realize fast imaging reconstruction for MIMO-SAR, with great reduction on the time consuming as compared with the BP algorithm and better accuracy compared with the Stolt migration. Additionally, due to its iterative nature in the range direction, the proposed algorithm is more flexible in treating more complicated scenarios, such as the image reconstruction in the multi-layer medium. A bistatic prototype imager was designed for the proof-of-principle experiments in THz band. The 3-D imaging results of different targets and computational complexity were also given to demonstrate the good performance of the proposed algorithm for THz MIMO-SAR imaging.

Highlights

Terahertz (THz) waves are generally referred to the spectrum from 0.1 to 10 THz, which lie in the gap between the microwave and infrared
EXPERIMENT SETUP To illustrate the performance of the proposed MIMO-SAR phase shift migration (PSM) algorithm in practical applications, as shown in Fig.9, a prototype imager was developed in the 0.1 THz band
The system was fabricated based on a microwave Vector Network Analyzer (VNA) combined with two transmitters to multiply the signal to the 0.1 THz band, and a receiver to convert the 0.1 THz signal to the intermediate frequency (IF) signal

Summary

Introduction

Terahertz (THz) waves are generally referred to the spectrum from 0.1 to 10 THz, which lie in the gap between the microwave and infrared. THz has many advantages due to its unique electromagnetic wave band. Unlike optical and infrared radiation, THz waves offer the property of being able to ‘see through’ obscuring materials such as clothing, cardboard, plastics, and wood with relatively little loss. Compared with microwaves and lower radio frequency waves, THz. The associate editor coordinating the review of this manuscript and approving it for publication was Thomas Kuerner. And attractively, resolutions in millimeter even sub-millimeter level for all the three spatial dimensions are available for an active imaging system in THz band, which is found to be promising for plenty of applications [1]–[10], such as security and safety screening, non-destructive testing (NDT) and evaluation.

Methods

Results

Conclusion