This article focuses on the 2D hybrid technique between the Frequency Domain Transmission Line Matrix Method (FDTLM) and the Wave Concept Iterative Procedure (WCIP). 3D hybridization has already been studied, but results may be improved through a better knowledge of method order. Consequently, developing 2D hybridization aims at understanding the hybridization in simplest problems, especially because Transverse Electric (TE) and Transverse Magnetic (TM) are uncoupled. Our study dwells on accuracy and convergence order of the 2D hybrid method, which will help for 3D mesh use. In this perspective, the scattering nodes and electromagnetic elds expressions are established in the 2D general case with anisotropic materials. As a result, validation examples are presented to check the approach.

In this study, the impact of finite ground plane edge diffractions on the amplitude patterns of aperture antennas is examined. The Uniform Theory of Diffraction (UTD) and the Geometrical Optics (GO) methods are utilized to calculate the amplitude patterns of a conical horn, and rectangular and circular waveguide apertures mounted on square and circular finite ground planes. The electric field distribution over the antenna aperture is obtained by a modal method, and then it is employed to calculate the geometrical optics field using the aperture integration method. The UTD is then applied to evaluate the diffraction from the ground planes' edges. Far-zone amplitude patterns in the E and H planes are finally obtained by the vectorial summation of the GO and UTD fields. In this paper, to accurately predict the H-plane amplitude patterns of circular and rectangular apertures mounted on square ground plane, the E-plane edge diffractions need to be included because the E-plane edge diffractions are much more intensive than those of the H-plane edge regular and slope diffractions. Validity of the analysis is established by satisfactory agreement between the predicted and measured data and those simulated by Ansoft's High Frequency Structure Simulator (HFSS). Good agreement is observed for all cases considered.

In this paper a novel compressor for static magnetic fields is proposed based on finite embedded transformation optics. When the DC magnetic field passes through the designed device, the magnetic field can be compressed inside the device. After it passes through the device, one can obtain an enhanced static magnetic field behind the output surface of the device (in a free space region). We can also combine our compressor with some other structures to get a higher static magnetic field enhancement in a free space region. In contrast with other devices based on transformation optics for enhancing static magnetic fields, our device is not a closed structure and thus has some special applications (e.g., for controlling magnetic nano-particles for gene and drug delivery). The designed compressor can be constructed by using currently available materials or DC meta-materials with positive permeability. Numerical simulation verifies good performance of our device.

Sparse microwave imaging is the combination of microwave imaging and sparse signal processing, which aims to extract physical and geometry information of sparse or transformed sparse scene from least number of radar measurements. As a primary investigation on its performance, this paper focuses on the performance guarantee for a one-dimensional radar, which detects delays of several point targets located at a sparse scene via randomly sub-sampling of radar returns. Based on the Lasso framework, the quantity relationship among three important factors is discussed, including the sub-sampling ratio ρ_M, sparse ratio ρ_K and signal-to-noise ratio (SNR), where ρ_M is the ratio of number of random sub-sampling to that of Nyquist's sampling, and ρ_K is the ratio of sparsity to the number of unknowns. In particular, to ensure correct delay detection and accurate back scattering coefficient reconstruction for each target, one needs ρ_M to be greater than C(ρ_K)ρ_KlogN and the input SNR be of order logN, where N is the number of range cells in scene.

In this paper, a modified Bayesian Optimization Algorithm (BOA), named M-BOA, is proposed to introduce a suitable mutation scheme for the traditional procedure in order to speed up the convergence of the algorithm and to avoid it to be trapped in local minima or to stagnate in suboptimal solutions. The proposed algorithm has been applied both to a specific mathematical test function and to sparse linear antenna arrays design, showing outperforming capabilities not only with respect to the standard BOA, but also with respect to other assessed global optimization methods.

The complex dispersion characteristics of the surface wave modes of plasma column loaded closed cylindrical waveguides have been investigated. The numerical results for partially or fully plasma loaded waveguides have been obtained from the Method of Moment(MOM), the exact dispersion equation and the quasistatic dispersion equation. A numerical technique based on the solution of the MoM has been proposed in order to obtain the complex propagation constant from the exact solution. The surface wave modes obtained from these methods have been presented comparatively in the figures. Thus, the insufficiency of the quasistatic approximation to obtain the complex surface wave modes has been shown. Additionally, the study involves a comprehensive literature review including physical descriptions and/or behavior in different physical media of surface wave modes and complex wave modes.

Specific emitter identification (SEI) is the technique which identifies the individual emitter based on the RF fingerprint of signal. Most existing SEI techniques based on the transient RF fingerprint are sensitive to noise and need different variables for transient detection and RF fingerprint extraction. This paper proposes a novel SEI technique for the common digital modulation signals, which is robust to Gaussian noise and can avoid the problem that different variables are needed for transient detection and RF fingerprint extraction. This makes the technique more practical. The technique works based on the signal's energy trajectory acquired by the fourth order cumulants. A relative smoothness measure detector is used to detect the starting point and endpoint of the transient signal. The polynomial fitting coefficients of the energy trajectory and transient duration form the RF fingerprint. The principal component analysis (PCA) technique is used to reduce the feature vector's dimension, and a support vector machine (SVM) classifier is used for classification. The signals captured from eight mobile phones are used to test the performance of the technique, and the experimental results demonstrate that it has good performance even at low SNR levels.

Doherty type Power Amplifier (DPA) design is one of the most practical efficiency enhancement methods that provide moderate linearity. Asymmetrical device usage and employment of bias adaptation are among the most commonly used Doherty architectures in recent applications. In this paper, the efficiency performances of bias adapted DPA and asymmetrical DPA are compared based on the new efficiency expression that is derived in terms of the conduction angle. The efficiency of bias adapted DPA is analyzed in terms of conduction angle of the peaking device; various bias waveforms are proposed and their effects on enhanced efficiency performance are demonstrated. This paper also facilitates an approach to determine the required relative periphery of the peaking amplifier in order to have a fully load modulated asymmetrical DPA. Both DPA structures are designed and implemented at the output power of 50 dBm with nearly 60% drain efficiencies in 6 dB load modulation region. The measurements verify the better efficiency characteristics of the bias adapted DPA and asymmetric DPA in comparison to the conventional DPA. For the first time in the literature, as a fair comparison, the performances of asymmetrical DPA and bias adapted DPA are compared on the same platform and their advantages as well as drawbacks are demonstrated using measurement results.

We hybridize vector Finite Element Method (FEM) and a Modified Multimodal Variational Formulation (MMVF) to the accurate and fast design of complex isotropic rectangular filters. The MMVF is applied to the full-wave description in the rectangular waveguides while the FEM characterizes waves in the arbitrarily shaped discontinuities. The proposed hybrid method is applied to the full-wave analysis of circuits with great practical interest (i.e., cross-shaped iris and multimode filters), thus improving CPU time and memory storage against several full-wave FEM based Computer Aided Design (CAD) tools (i. e. HFSS High Frequency Structural Simulator). The performances of the proposed hybrid method are validated with experimental results and HFSS simulations.

This paper describes the design, modeling and optimization of an efficient ISM band dual patch rectenna capable of achieving more than 80% RF-to-DC conversion efficiency at low/medium power densities. The circuit is based on a full-wave rectifier, designed and optimized at 2.45 GHz with ADS software and the FDTD algorithm. The performances of the rectenna have been accurately predicted using the full-wave 3D-FDTD method extended to lumped linear and non-linear elements. It exhibits 73% (<V_DC = 1.1 V for R_L= 1.2 kΩ) measured efficiency at a low power density of 14 μW/cm² and 84% (V_DC = 1.94 V) at 43 μW/cm². The differences between the experimental and FDTD simulated efficiencies are less than 3%. The proposed circuit is particularly suitable for low/medium power recycling and power remote supply of wireless sensors, sensor nodes and actuators.

A compact coupled-line hairpin resonator is proposed and analyzed for designing a novel bandpass filter (BPF) in this letter. Compared with conventional stepped-impedance and stub-loaded resonator, the proposed resonator can produce three transmission zeros, which can be applied to achieve a wide and highly-attenuated upper stopband. To validate this attractive feature, a microstrip BPF is designed and fabricated with the center frequency at 2.4 GHz and a fractional bandwidth of 6%. Measured frequencies responses show a wider upper stopband up to 6.9 GHz (2.9f₀) with insertion loss higher than 20 dB.

Radar echo of ballistic midcourse target contains unique motion information of the target, which can provide important evidence for target recognition. A wideband radar echo simulation model for midcourse precesional target is developed, where the micro-motion model, electromagnetic scattering calculation and linear frequency modulated (LFM) radar signal model are integrated. Firstly, the position variation of each scattering center of the moving target is analyzed. Then, the high frequency method is used to judge the masking effect of scattering centers of the rotational symmetry target. Finally, the wideband radar echo is simulated, and the impacts of high speed translational motion, non-precession movement and non-idealization of the scattering centers on the echo are also analyzed.

A novel energy harvesting antenna for various wireless transceivers is proposed. This antenna is composed of two parts, the main and the parasitic radiator. The main radiator has the same role as a general element antenna. i.e., to transmit and receive the RF signal. The parasitic radiator is used to gather the RF power from the main radiators, which mostly do not contribute the main radiator's electrical performance. Thus, we can generate DC power using the dissipated RF energy that is radiated from the main radiator. The main radiator is designed as a printed dipole and the parasitic radiator has a two-turn loop structure fabricated on a substrate. The main radiator is vertically placed on the ground and inserted in the rectangular slit of the substrate of the parasitic radiator. The height of the parasitic radiator can be controlled by two supporters. In the design process, we analyzed how the antenna performance changed when adjusting the height of the parasitic radiator and thus determined its optimal height.

In this paper, we introduce a high order finite element (FEM) implementation using perfectly matched layer (PML) for the scattering by plasmonic structures inside layered media. The PML is proven to be very accurate and efficient by a comparative analysis with a commercial FEM software and the Multiple Multipole Program (MMP). A convergence analysis using hp-adaptive refinement inside the PML layer shows that adaptive mesh refinement inside the PML layer is most efficient. Based on this convergence analysis an hp-strategy is proposed, which shows a remarkable error reduction for small additional computational costs.

Non-line-of-sight (NLoS) maritime mobile radio channel in 5 GHz band is experimentally investigated in this paper through wideband channel soundings. During the measurements, the transmitter was installed onboard a speed boat, while the receiver was placed on the roof top of a building on shore. Different types of cargo ships anchored off the east coast of Singapore were examined as obstructions for the NLoS propagations. Besides power delay profile (PDP), stand-off distance is introduced in this work to analyze the NLoS propagations associated with three different types of cargo ships. The measured PDPs and stand-off distances are found to be comparable qualitatively with the simulated results using 3-D ray tracing. The reported information is found to be useful for military applications such as unmanned surface vehicles (USVs) in maritime environments or surveillance.

In this paper, a stage wise realization of compact Bluetooth - UWB dual-band diversity antenna with WiMAX and WLAN band-notch characteristics is presented. The proposed structure consists of two co-planar semicircular dual band-notch monopole antennas, mounted with planar spiral. Individual antenna configuration provides an impedance bandwidth (VSWR < 2) for dual-band i.e. both Bluetooth and UWB bands. For dual band-notch characteristic, two sets of spirals are capacitively coupled with the feed line of antenna. This configuration provides band-notch (VSWR > 2) for WiMAX i.e. (3.3-3.6 GHz) and WLAN (5.13-5.85 GHz) bands. For enhancing reception capabilities of the proposed structure, twin coplanar antennas are used to fulfill diversity requirements. However, due to coplanar and close proximity to each other, there is high possibility of mutual coupling between coplanar antenna elements. To address the mutual coupling between elements, cross-strip variable-sized frequency selective structures are used. Antenna diversity of the proposed structure is validated by measuring radiation pattern characteristic and envelop co-relation factor (ECC). A good agreement between measured and simulated responses ensures that the proposed diversity antenna can be used for interference free Bluetooth/UWB dual-band applications.

A low radar cross section (RCS) metamaterial absorber (MMA) with an enhanced bandwidth is presented both numerically and experimentally. The MMA is realized by assembling three simple square loops in a three-layer structure according to the idea of separating electric and magnetic resonances. Different from one-layer MMA, the proposed MMA can effectively couple with the electric and magnetic components of the incident wave in different positions for fixed frequency, while, for different frequencies, it can trap the input power into different dielectric layers and absorb it in the lossy substrate. Experimental results indicate that the MMA exhibits a bandwidth of absorbance above 90% which is 4.25 times as that of one-layer MMA, and 10 dB RCS reduction is achieved over the range of 4.77-5.06 GHz. Moreover, the cell dimensions and total thickness of the MMA are only 0.17λ and 0.015λ, respectively. The low RCS properties of the MMA are insensitive to both polarization and incident angles.

In this paper, high resolution range profile-jet engine modulation (HRRP-JEM) analysis is extended by including quantitative estimation of the jet engine location and extraction of the JEM micro-Doppler component. Based on a parametric model of the range cell data, signal eccentricity was introduced for the purpose of determining the jet engine location. Then, complex empirical mode decomposition (CEMD) was employed to extract the embedded JEM component. The signal eccentricity also served as an auxiliary means of CEMD-based micro-Doppler extraction. Application to the simulated HRRP-JEM data demonstrated that the analysis results described in this paper could be useful for advanced radar target recognition with HRRP-JEM.

Polarization reconfigurable patch antennas which can switch polarization states among vertical and horizontal linear polarization (LP), left- and right-hand circular polarization (CP) is demonstrated in this paper. The original orthogonal linear polarized antenna is a square patch fed by two ports at the adjacent edges. CP operations can be activated by introducing perturbations at the opposite corners of the patch. If a diode is loaded on every perturbed corner, the antenna polarization states can be alternated by controlling the bias voltage of two PIN diodes. Perturbation elements can be cut on the patch or on the ground. Two antenna prototypes are suggested, simulated, and verified by experiments. These polarization reconfigurable antennas have good antenna performances of low reflection coefficient, axial ratio, and cross-polarization (X-pol), and high isolation between two LP operations. They have concise structure with only two PIN diodes being required. The two reconfigurable antennas are low cost and can be integrated easily in wireless communication systems.

This paper presents a new design of high-gain low-profile resonant cavity antenna. A novel partially reflecting surface (PRS) is adopted as the superstrate with the characteristics of high-reflection magnitude and low-reflection phase that allows the reduction of cavity height to about λ/8 and the enhancement of the gain by 10.73 dB. Several significant parameters that characterize the PRS superstrate are investigated based on the unit cell simulation. The measured results show that this method is effective, and this structure can provide a high-gain at the operating frequency. The measured results agree reasonably well with the simulated ones.