A Novel Fast Near-Field Electromagnetic Imaging Method for Full Rotation Problem

Abstract

Abstract-A fast method for electromagnetic imaging from monostatic full rotational near-field scattering is proposed in this paper. It is based on circular spectrum theory which exploits the Fourier decomposition of the targets distribution instead of point by point imaging in earlier works. The novelty of the proposed method is that it simplifies the relationship between the spatial frequency domain and the scattering field. The near-field scattering is analyzed by expanding the distance to Taylor series at the centre of the targets zone. The nearfield focus function is then transformed to spatial frequency domain and evaluated by the method of stationary phase. The imaging result is given by two-dimensional inverse Fourier transformation from spatial frequency domain of targets. The proposed method is validated by comparing the simulation results of distributed targets with the tomographic imaging. The dynamic range of imaging result is derived by distributed targets with different reflection coefficient. Furthermore, the experiment is also conducted in microwave chamber at Ku band with target placed on the turntable.

Creation of Super-Resolution Non-Diffraction Beam by Modulating Circularly Polarized Lightwith Ternary Optical Element

“…However, it is difficult to realize the spot below diffraction limit due to the optical diffraction limit effect. In order to break through the diffraction limit, lots of ways to obtain super-resolution non-diffraction beam were presented and discussed such as hyperlens and super-oscillatory lens [9][10][11], utilizing superlens to turn evanescent waves into propagating waves and obtain subwavelength imaging [12,13], handling of the evanescent waves with near field diffraction structures [2,14], and super-resolution apodization through pupil masks [14][15][16][17][18]. In these methods, the superresolution pupil filters (or phase plates) with amplitude and phase modulations are always hot subjects.…”

Estimating the Reduction of Radiated Emissions From TFT-LCD Panel Using Network Analyzer With a Bulk Current Injection Probe

“…However, performing far-field measurements is very costly and time-consuming. Another common method of measuring PCB radiated emissions is to use a magnetic or electric field probe for near-field scanning of the PCB surface [9][10][11][12][13]. Although the associated test setup and procedure are simpler than those for far-field measurement, the near-field scan results are more effective for locating the source of radiated emission than for predicting radiated emission levels as required by EMC specifications.…”

A Near-Field 3d Circular Sar Imaging Technique Based on Spherical Wave Decomposition

“…These merits make microwave imaging systems have great potential in the field of concealed objects detection [4][5][6][7][8]. Besides detecting concealed objects in security check, microwave near-field imaging is also applied to non-destructive testing for quality compliance industrial procedures, images acquisition of vivo tissues for biological and medical studies and far-field radar cross-section (RCS) prediction with near-field measurement of target back-scattering properties [9][10][11][12]. So, the microwave near-field imaging has become an attractive topic.…”

“…Circular SAR (CSAR) is a special aperture synthetic mode [12,[16][17][18]. In this mode, the target is illuminated by radar over a circular trajectory.…”