Micro‐motion parameter extraction of rotating target based on vortex electromagnetic wave radar

Abstract

The vortex electromagnetic (EM) wave radar has the potential to obtain more accurate micro-motion parameters for target recognition. However, with the existing algorithms of micro-motion parameter extraction it is difficult to obtain the real rotation radius and tilt angle of a rotational target in the presence of multiple scattering points in the radar beam. A micro-motion parameter extraction algorithm for rotating targets based on the vortex EM wave radar is proposed in this article. The angular Doppler is obtained from the dualmode vortex EM echoes. The time interval between the maximum and minimum angular Doppler frequency is derived. The relationship between the time interval and micromotion parameters is shown. By combining the linear Doppler and the angular Doppler, the micro-motion parameters are roughly estimated. Then, fine micro-motion parameters are obtained by using an iterative soft threshold algorithm. The proposed algorithm can extract the real rotation radius and tilt angle in the case of multiple scattering points. The performance and robustness of the algorithm are proved by simulations.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Micro-Motion Parameter Extraction of Multi-Scattering-Point Target Based on Vortex Electromagnetic Wave Radar

“…where σ p is the scattering coefficient of the scattering point, P; f c is the carrier frequency of the signal; a is the radius of the UCA; c is the speed of light; J l (•) is the first kind of l-order Bessel function; k(t) = 2π( f c + Kt)/c; τ p (t m ) = 2r(t m )/c; and, among others, r p (t m ), ϕ p (t m ), θ p (t m ) represent the distance from the scattering point to the antenna array, the azimuth angle, and the elevation angle, respectively. According to [2], the echo signal after dechirp can be expressed as:…”

“…Over the past few years, vortex electromagnetic waves have attracted increasing attention in the fields of rotation Doppler parameter estimation [1,2], OAM modulated wireless communication [3,4], and quantum applications [5] due to their unique spiral phase structure and orthogonal characteristics [6]. In addition, when a moving target is irradiated by vortex radar, a unique wave front shows the characteristic of angular diversity and the vortex echo contains more target information, which allows electromagnetic vortex radar to be utilized to improve the accuracy of object identification [7,8].…”

High‐speed target imaging for vortex electromagnetic wave radar

“…For the left subgraph, it is obvious that as the target speed v increases, the azimuth error becomes larger; however, the maximum in the general scene is on the order of 10e-5. The right subgraph reflects that as z T decreases, the azimuth error becomes larger and the maximum error is also on the order of 10e-4, so (8) has good adaptability in this imaging scenario. According to the above analysis, by combining the phase terms related to t s in Equation ( 8), the preprocessed signal can be obtained as follows:…”

“…The electromagnetic (EM) vortex radar has attracted considerable interest of researchers in recent years. Compared with classical EM waves, VEMW carrying OAM has higher dimensional information-modulation freedom, which paves the way for the OAM's applications in radar target detection and imaging [8]. Under the illumination of the VEMW radar, the target surface will have spatially different scattering characteristics; thus, more target information will be contained in the received echo.…”

Vortex-electromagnetic-wave-based ISAR imaging for high-speed maneuvering targets

“…In the past 30 years, due to unique spiral phase structure and orthogonal characteristics 1 , vortex electromagnetic wave has attracted increasing attention in the fields of rotation Doppler parameter estimation 2,3 , OAM modulated wireless communication [4][5][6] , quantum application 7 . In addition, when the moving target is irradiated by vortex radar, the unique wavefront shows the characteristic of angular diversity, the dual relationship between the OAM mode number and the azimuth angle, so the scattered echo in the target area will contain more relevant information, which make the electromagnetic vortex radar is expected to develop into a new imaging mechanism.…”