Zhen-Sen Wu

Xidian University

Millimeter-wave channel modeling is the basis of fifth-generation (5G) communication network design and applications. In urban microcellular environments, the roughness of wall surfaces can be comparable to the wavelengths of millimeter waves, resulting in walls that cannot be considered as smooth surfaces. Therefore, channel modeling methods based...

Complex-terrain clutter presents serious nonuniformity, which has a significant impact on radar target detection, communication, and navigation. The accurate acquisition of the clutter characteristics by measurement or calculation for large and complex terrains has always posed a challenge due to the high costs of the measurement, as well as the in...

Due to its orbital angular momentum (OAM), optical vortex has been widely used in communications and LIDAR target detection. The OAM mode recognition based on deep learning is mostly based on the basic convolutional neural network. To ensure high-precision OAM state detection, a deeper network structure is required to overcome the problem of simila...

To improve the robustness of vortex beam transmission and detection in the face of atmospheric turbulence and to guarantee accurate recognition of orbital angular momentum (OAM), we present an end-to-end dynamic compensation technique for vortex beams using an improved cycle-consistent generative adversarial network (CycleGAN). This approach transf...

The Doppler spectra of sea echoes, which contain abundant information on floating scatterers, are important for exploring the characteristics of sea clutter. Using sea clutter data at low grazing angles observed by a coherent ultra-high frequency (UHF) radar located on Lingshan Island in the Yellow Sea, China, this study conducted detailed research...

The analysis of marine environmental parameters plays a significant role in various aspects, including sea surface target detection, the monitoring of the marine ecological environment, marine meteorology and disaster forecasting, and the monitoring of internal waves in the ocean. In particular, for sea surface target detection, the accurate and hi...

Accurate prediction of rain attenuation is critical for the design of terrestrial line‐of‐sight link systems above 5 GHz, particularly for millimetre‐wave frequency. Anomalous behaviour in the adjustment factor in existing rain attenuation prediction models is significantly greater than 1 at short distances and has been reported. To solve this prob...

The laser beams were scattered and attenuated when they propagate in fogs for laser communication, laser remote sensing detection. For different density and droplets distribution of fogs, the laser scatter and attenuation are different, the correspond mechanism need thorough investigation. The characteristics of laser beam scattering in different t...

A full analytical theory for the reflection and transmission of an Airy beam impinging on a dielectric surface is presented. Based on the plane-wave angular spectrum expansion, the analytical expressions for the reflected and transmitted fields comprising beam modes are derived. To improve the calculation accuracy, the actual beam field retains up...

To systematically study the influence of slant atmospheric turbulence on the inverse synthetic aperture lidar (ISAL) imaging, the atmospheric random phase screen with the modified von Kármán spectrum was numerically simulated via the fast Fourier transform spectral inversion method. Intensity phase distribution and brightness images of the Gaussian...

In an effort to address the problem of the insufficient accuracy of existing orbital angular momentum (OAM) detection systems for vortex optical communication, an OAM mode detection technology based on an attention pyramid convolution neural network (AP-CNN) is proposed. By introducing fine-grained image classification, the low-level detailed featu...

At present, 5G base stations are densely distributed in major cities based on improving user concentrations and the large demand for services in urban hotspot areas. Moreover, 5G communication requires more accurate communication propagation loss (PL) monitoring. Low-build areas, such as suburbs and rural areas, are prone to forming relatively stab...

The multiple-input–multiple-output (MIMO) phase of the received signal is the most important parameter in the line-of-sight MIMO (LOS MIMO) system. The MIMO phase turbulence often occurs in practical applications, and the LOS MIMO system cannot operate normally in severe cases. However, there is no practical MIMO phase prediction method presently....

Based on marine environmental factors of different sea areas, a high-performance sea clutter time series modeling algorithm for the real sea surface is developed to study the amplitude mean and Doppler spectrum characteristics of sea clutter. The European Centre for Medium-Range Weather Forecasts (ECMWF) data set (ERA-Interim) and ESA’s soil moistu...

Inverse synthetic aperture LiDAR (ISAL) breaks through the limitations of the diffraction limit and achieves ultra-long-distance radar imaging with centimeter-level resolution. However, because ISAL obtains a high resolution, it is accompanied by a high sampling rate and a large data volume, and the processing process is complicated, which is not c...

The reflection and transmission of a finite-power Airy beam incident in a dielectric slab are investigated by an analytical method. Based on the plane-wave angular spectrum expansion and Fresnel approximation, the analytical expressions of the reflected field, internal field as well as transmitted field in each region are obtained. Through numerica...

In this letter, a novel integrated physical optics (PO) method for calculating high-frequency scattering of nonplane wave is proposed, and the orbital angular momentum (OAM) wave scattering upon an electric-large metallic sphere is illustrated. A high-order Bessel wave expanded by a series of plane wave angular spectra is selected to irradiate a pe...

Inverse synthetic aperture lidar (ISAL) has overcome the optical diffraction limit and realized radar imaging with centimeter‐level resolution at ultra‐long distances. Taking a two‐dimensional Gaussian rough surface as an example, a method for calculating the scattered echo under the Kirchhoff approximation based on two‐dimensional Fourier transfor...

With the rapid development of the fifth-generation (5G) mobile communication technology, the application of each frequency band has reached the extreme, causing mutual interference between different modules. Hence, there is a requirement for detecting filtering and preventing interference. In the troposphere, over-the-horizon propagation occurs in...

Based on the generalized Lorenz Mie theory, the propagation and scattering properties of a uniaxial anisotropic spherical particle illuminated by double zero-order Bessel beams with arbitrary propagation and polarization directions are studied. The propagating and scattering characteristics are compared with those of a uniaxial anisotropic spherica...

The characteristics of sea clutter in real marine environments in different sea areas play a vital role in military industry such as radar detection, remote sensing, SAR imaging, and situational awareness. In this paper, a deep neural network sea clutter model is proposed based on the sea clutter big data under the real marine environment to study...

Based on the excellent and broad prospect of the vortex beams in military application, it is necessary to evaluate the scattering characteristics of classical Bessel beam upon a perfect electrical conductor (PEC) blunt cone model of aircraft structure. First, a Bessel beam is expanded by a series of plane wave spectra. Then, combining the physical...

The anomalous propagation conditions, particularly the tropospheric ducts, severely impact the regular operation and performance evaluation of radio devices in the atmospheric boundary layer. Therefore, it is necessary to provide the regional distribution of tropospheric ducts for utilizing or avoiding these abnormal propagation phenomena. As signi...

Thomson scattering of a vector Bessel vortex beam (VBVB) by a non-relativistic electron is studied in this paper in order to explore the prospects of vortex beams in Thomson scattering diagnostic in ionospheric or laboratory plasmas. Combining with the plane wave angular spectrum representation of a VBVB, the expressions of scattered electric and m...

Deterministic channel models, such as the three-dimensional (3D) ray launching method, can yield wireless channel parameters. In the non-line-of-sight (NLOS) propagation, the outdoor 3D ray launching method that considers diffraction effects is more accurate than the one that does not. While considering the diffraction effect, obtaining the diffrac...

The oceanic tropospheric duct is a structure with an abnormal atmospheric refractive index. This structure severely affects the remote sensing detection capability of electromagnetic systems designed for an environment with normal atmospheric refraction. The propagation loss of electromagnetic waves in the oceanic duct is an important concept in oc...

This paper provides an analytic method to study propagation characteristics of a linearly polarized Bessel vortex beam through a homogeneous magnetized plasma slab. The incident Bessel vortex beam, as well as the reflected, transmitted and internal fields are expanded in terms of cylindrical vector wave functions (CVWFs). The effects of plasma thic...

In this paper, theory concerning scattering of EM (electromagnetic) waves with orbital angular momentum (OAM) is presented, in which a metallic sphere illuminated by OAM waves is adopted to simplify the study. Based on the series expansion and the physical optics (PO) methods, expressions of incident and scattered OAM waves are obtained. To get the...

The reflection and transmission of a Bessel vortex beam incident on a stratified uniaxial anisotropic slab are analytically solved by use of the expansion of cylindrical vector wave functions (CVWFs). This work is an extension of our previous paper, in which the reflection and transmission of a Bessel vortex beam incident on a homogeneous uniaxial...

The study of sea clutter reflectivity plays an essential role in radar performance evaluations in the military industry. The industrial bodies are trying to apply the sea clutter intelligent processing technology to the radar system with the form of the Internet of Things and Industry 4.0. Many sea clutter reflectivity models that have been propose...

An investigation into the orbital angular momentum (OAM) cross talk of multiple coaxial terahertz vortex beams propagating through an inhomogeneous unmagnetized plasma slab was conducted using the vector angular spectrum expansion method. For the double Gaussian distribution model of plasma sheath, considering the incidence of coherent vortex beams...

In this paper, a compact circularly polarized (CP) antenna with omnidirectional radiation is presented, which has a central symmetric configuration (CSC) and planar structure. It consists of three identical end-fire CP antenna units. Based on the combination of two parallel complementary current sources, each unit cell can be realized by a scallope...

In this paper, the scattering characteristics an infinite dielectric periodic surface are investigated in detail. The Fourier expression of scattering field of the periodic surface is obtained by using the Rayleigh hypothesis and the Floquet theorem. Using the extended boundary condition method and the T‐matrix method, the scattering amplitude fact...

The scattering characteristics of the periodic surface of infinite and finite media are investigated in detail. The Fourier expression of the scattering field of the periodic surface is obtained in terms of Huygens’s principle and Floquet’s theorem. Using the extended boundary condition method (EBCM) and T -matrix method, the scattering amplitude f...

This erratum makes corrections to Eqs. (7) and (9) of Opt. Lett. 44, 1452 (2019).OPLEDP0146-959210.1364/OL.44.001452

An efficient facet-based composite scattering model (FBCSM) is developed for calculating the time-evolving electromagnetic (EM) scattering field (TESF) to study the normalized radar cross section (NRCS) and Doppler spectrum characteristics from dynamic sea surfaces. The dynamic sea surface comprises two-scale profiles: small-scale capillary ripples...

In this Letter, to the best of our knowledge, a novel anisotropic surface impedance holographic metasurface antenna for generating orbital angular momentum (OAM) is developed through design, fabrication, and measurement at radio frequencies. The classical leaky-wave theory and a microwave holography method are combined to realize vortex waves carry...

In this paper, an anisotropic holographic metasurface design is proposed, fabricated, and measured, to demonstrate that it can generate multiple beams with different orbital angular momentum (OAM) modes in the radio-frequency domain. The anisotropic holographic metasurface is composed of an array of quasi-periodic square particles with a rectangula...

The infrared (IR) radiance of an aerial target owing to the reflection of the external sources including the sun, atmosphere and the earth’s surface is a key factor to consider in the modeling and simulation of the IR image in the studies of target detection and tracking, guidance and camouflage. Since the radiations of atmosphere and the earth’s s...

On the basis of vector plane wave spectrum expansion, the reflection and transmission characteristics of an arbitrarily polarized terahertz Bessel vortex beam by an inhomogeneous unmagnetized plasma slab are investigated. Magnitude profiles of electric field components in the transverse plane, which is perpendicular to the central axes of the refle...

To study of the infrared signature of an aerial target, it is required to precisely model the background radiation. Simple empirical models or standard atmospheric models in LOWTRAN/MODTRAN were used in earlier studies. To further precisely model the thermal radiation of earth’s surface and atmospheric radiance/transmittance, the atmospheric profil...

Based on the generalized multi-particle Mie equation (GMM) and Electromagnetic Momentum (EM) theory, the lateral binding force (BF) exerted on multilayered spheres induced by an arbitrary polarized high-order Bessel beam (HOBB) is investigated with particular emphasis on the half-conical angle of the wave number components and the order (or topolog...

Bessel vortex beams are widely studied, since their intensity is independent of the propagation distance, and also their original field intensity distribution can be reconstructed after passing through an obstacle. Therefore, such beams are more advantageous for long-distance communication, optical imaging, and other potential applications. Based o...

In this paper, a dual-band dual-polarized reflectarray for generating dual beams with respect to carrying two different orbital angular momentum (OAM) topological charges operating in the C-band in horizontal polarization and in the X-band in vertical polarization is proposed, with two separate horns performing on the two proposed bands as the feed...

The development of a time-evolving oceanic surface model (TOSM) is important for the accuracy of determining electromagnetic scattering properties from the sea surface in oceanic remote sensing, target detection, and synthetic aperture radar imagery at arbitrary incident angles, especially small grazing angles. The double superimposition model (DSM...

Analytical solution to the scattered field and near-surface field of a multilayered chiral sphere illuminated by a high-order Bessel vortex beam (HOBVB) are investigated. Using the vector wave theory, the expansion coefficients of a HOBVB in terms of spherical vector wave functions (SVWFs) are derived. Based on the fields expansion in each region a...

Based on the angular spectrum expansion and the $4\times 4$ transfer matrix method, an investigation into the reflection, transmission, and absorption of vortex beams in an inhomogeneous magnetized plasma slab is presented. The reflected and transmitted electric fields are expressed by the inverse Fourier transform of the product of the reflected...

We model the effect of the off-axis distance of edge dislocation on the transmission of mixed higher-order optical vortex-edge dislocations in atmospheric turbulence. We find that when mixed dislocations beams propagate through atmospheric turbulence, the higher-order optical vortex will break down, and the topological charge is conserved in the pr...

This study presents a Bayesian approach based on a color image demosaicking algorithm. The proposed method is composed of pointwise and patchwise measurements. The estimation of the missing pixel is formulated as a maximum a posteriori and a minimum energy function. By utilizing Bayesian theory and some prior knowledge, the missing color informatio...

Based on the generalized multi-particle Mie equation (GMM) and Electromagnetic Momentum (EM) theory, the lateral binding force (BF) exerted on bi-sphere induced by an arbitrary polarized high-order Bessel beam (HOBB) is investigated with particular emphasis on the half-conical angle of the wave number components and the order (or topological charge...

We establish a model for lognormal distribution of monomer radius and number of alumina particle clusters in plume. According to the Multi-Sphere T Matrix (MSTM) theory, we provide a method for finding the statistical average of optical properties for alumina particle clusters in plume, analyze the effect of different distributions and different de...

Within the framework of the generalized multi-particle Mie (GMM) theory, analytical solution to electromagnetic scattering of two interacting homogeneous uniaxial anisotropic spheres by a Laguerre–Gaussian (LG) vortex beam is investigated. The particles with different size and dielectric parameter tensor elements are arbitrarily configured. Based o...

The effective extraction of optical surface roughness and defect characteristic provide important realistic values to improve optical system efficiency. Based on finite difference time domain/multi-resolution time domain (FDTD/MRTD) mixed approach, composite scattering between a slightly rough optical surface and multi-body defect particles with di...

This paper investigates the characteristics of reflected and transmitted fields of a vector Bessel vortex beam through multilayered isotropic media on the basis of the vector angular spectrum expansion and presents the effects of media on intensity, phase, and polarization. The method is verified by studying the reflection and transmission on a sin...

In order to provide a theoretical basis for nondestructive examination, a calculation model for the difference scattering fields between a slightly rough optical surface and multiple inlaid defect particles is established by the finite difference time domain (FDTD) method. The Monte Carlo method is used to solve the problem of the optical surface w...

In this paper, diffusion limited aggregation (DLA) algorithm is improved to generate the alumina particle cluster with different radius of monomers in the plume. Scattering properties of these alumina clusters are solved by the multiple sphere T matrix method (MSTM). The effect of the number and radius of monomers on the scattering properties of cl...

In this paper, we introduce an efficient demosaicking method based on an advanced nonlocal mean (NLM) filter using adaptive weight with consideration of both neighborhood similarity and patch distance. The to-be-interpolated missing color information is considered to be populated by the weight average of directional estimation in six directions: no...

The laser radar cross section (LRCS) is a key parameter in the study of target scattering characteristics. In this paper, a practical method for calculating LRCSs of rotationally symmetric targets is presented. Monostatic LRCSs for four kinds of rotationally symmetric targets (cone, rotating ellipsoid, super ellipsoid, and blunt cone) are calculate...

The electron energy distribution function is investigated when the ionosphere is illuminated by powerful HF radio waves from the ground. With the measurement of airglow emission at 630.0 nm with red lines, 557.7 nm with green lines and 844.6 nm in ionospheric heating experiments conducted at HAARP and EISCAT, the electron energy distribution functi...

We simulate the clusters of alumina particles using the parallel diffusion limited aggregation algorithm (DLA), and solve the scattering matrixes of the alumina particles in different phase states (alpha phase, gamma phase and liquid) through the multiple sphere T matrix method in UV. The effect of the number of monomers, fractal dimension and inci...

This paper considers the reflection and transmission characteristics of a Laguerre-Gaussian (LG) beam in a dielectric slab. The fields of the reflected and transmitted beams are described based on plane-wave angular spectrum representation. Using the generalized Fresnel amplitude reflectance and transmittance, the reflected and transmitted fields i...

The wavelet domain Wiener filter has been widely adopted as an effective image denoising method that has low complexity. In this paper we propose a novel Wiener filter with high-resolution estimation that determines the signal power while preserving the edge information. We assume that a noisy image is composed of noise and the original image, whic...

In this paper, we introduce an efficient image demosaicking method using a bilateral filter and directional differentiation with consideration of both the spatial closeness and the similarity between the interpolated pixel and the neighbor pixels. Spatial closeness is considered as spatial locality. We utilize an adaptive weighted average to estima...

When flying at a high speed or ultra-high speed, The hypersonic aircraft will react violently with the flow nearby. So some density and temperature distribution characteristics appear near the wall. These features will affect the optical imaging system resolution of the target image, and generate pneumatic optical effect. In this paper, we establis...

Based on the Planck's law and integrality the directional hemisphere reflectivity (DHR) and the Kirchhoffs law. And referred to the Torrance-Sparrow model and the five-parameter semi-empirical model, a new Bidirectional reflection distribution function model (BRDF) is developed in different temperature of material surface, this model will be applic...

The analytical theory for the scattering of a uniaxial anisotropic illuminated by a Laguerre-Gaussian vortex beam is presented. Based on the complex source point method and the relation between Hermite polynomial and Laguerre polynomial, the expansion of Laguerre-Gaussian vortex beam expanded in terms of spherical vector wave functions is derived....

This letter presents a field expansion of the solution to three-dimensional electromagnetic scattering problems of a uniaxial anisotropic spheroidal particle illuminated by an off-axis Hermite-Gaussian (HG) beam. Using the complex-source-point method, and the relationship between spherical and spheroidal vector wave functions (VWFs), a method is pu...

Laser sheet is of great practical importance in various fields, such as particle image velocimetry and probe detections. On the contrary to Gaussian beam, laser sheet is the beam focused by a cylindrical lens. In order to better understand the physical mechanism, the paper is devoted to the description of the interaction between a multilayered sphe...

Combing the practical situation of nondestructive examination, the analysis of difference field scattering properties between slightly rough optical surface and inlaid particles are researched by the method of Finite Difference Time Domain(FDTD). In wiew of the half-space problem about optical surface and inlaid particles, The perfectly matched lay...