After reaffirming that the macroscopic dipolar electromagnetic equations, which today are commonly referred to as Maxwell's equations, are found in Maxwell's Treatise, we explain from his Treatise that Maxwell defined his displacement vector D as the electric polarization and did not introduce in his Treatise or papers the concept of electric polarization P or the associated electric-polarization volume and surface charge densities, -n.P and n.P, respectively. With this realization, we show that Maxwell's discussion of surface charge density between volume elements of dielectrics and between dielectrics and conductors becomes understandable and valid within the context of his definition of electric polarization as displacement D. Apparently, this identification of D with electric polarization in Maxwell's work has not been previously pointed out or documented except very briefly in [2].

There is a large body of literature for electrically-small loop receiving antennas including more recent work in demagnetization effects for magnetic materials which are used for reducing antenna size. Optimal design of loop antennas requires understanding the electromagnetic principles and is limited by the accuracy of predicting the electromagnetic parameters (resistance, inductance, capacitance, effective permeability, sensitivity). We present the design principles for electrically-small loop receiving antennas including recommended formulas, a novel approach to optimal design, and an application example for use in the VLF/LF band (1-100 kHz) for two different ferrite-core loop antennas including the optimum coil parameters. Using a ferrite magnetic core greatly complicates analysis and prediction of resistance, inductance, and sensitivity as a function of frequency due to the dependence on core material properties, core geometry, and wire coil geometry upon the core (capacitance is typically negligibly affected). Experimental results for the two ferrite-core loop antennas and an air-core loop antenna validate the optimal design approach with good overall agreement to theoretical prediction of resistance, inductance, and sensitivity. Discussion and comparison between air-core and ferrite-core designs demonstrate the trade-off between outer diameter, length, and mass vs. sensitivity.

Based on a novel right-angled triangle artificial line, a branch-line coupler is designed in this letter. The measured results indicate that the proposed branch-line operates at 0.975 GHz with a stopband bandwidth more than 15f_c. Here, f_c is the center frequency of the coupler. Importantly, the suppression levels in the stopband are better than 15 dB. Besides, its occupied size is about 23.18×22.5 mm², which is only 16.5% of a traditional one at the same operating band. In practice, the proposed branch-line coupler can be used in compact systems which require good high-order harmonic suppression.

A new design of a printed Yagi-Uda antenna is presented. The main idea to be directive and large bandwidth is to replace the driver element associated with its reflector by a directional curved disk monopole, and the directors by flat disks monopole. It requires the use of a ground plane to simplify feeding. The study of configuration of the dimensions, the number and the dispositions of the directors elements allows a return loss less than -10 dB over 20% bandwidth centered at 5 GHz. Also, a high gain of 13 dBi is obtained with a maximum radiation direction at 26° elevation from the azimuth due to a limitation of the ground plane. This gain remains superior to 10 dBi over the bandwidth. The simulation results are in good agreement with the measurements for return losses, radiation patterns, and gain.

In this paper, a numerical algorithm for computation of electric and magnetic fields inside a multilayer cylindrical structure with an arbitrary number of homogeneous layers is presented. Each layer can have arbitrary value of electrical conductivity, permeability and permittivity. Theoretical background of the model is based on Maxwell equations where modified Bessel functions have been chosen for solution formulas. Modified Bessel functions are also scaled to avoid underflow/overflow issues. This results in a numerically robust and highly accurate numerical algorithm for computation of electric and magnetic fields inside a multilayer conductor. Using the derived expression for electric field on the surface of the conductor, the formula for per-unit-length internal impedance of the general multilayer cylindrical conductor is also obtained.

Development of Compartment Syndrome (CS) could affect blood flow to muscles, nerves, and as a result could causes permanent damage to tissues and nerves with risk of amputations and even death. The lack of non-invasive clinical diagnosis of compartment syndrome has led to thousands of permanent nerve and tissue damages. This paper aims to present a novel method, design concept, and numerical realization of non-invasive Radio Frequency (RF) based detection of compartment syndrome. The proposed method uses electromagnetic waves, produced by a small printed antenna at frequency of 300 MHz for identifying compartment syndrome. The effects of compartment syndrome and changes on tissue electrical properties are taken into account, since the ways in which electrical properties differences between normal and injured tissue should aid diagnosis on injured area by RF-wave radiation. We used a numerical leg model to identify inter-compartmental edema size of the lower leg, the most commonly effected area for patients. Because the antenna can be made very small, RF-based detection of compartment syndrome applications can be extended to small-scale devices. Numerical studies show that compartment syndrome as small as 5 ml can be detected with this method. We hope that our novel method will improve both diagnosis and overall patient care for compartment syndrome. Moreover, this detection system is intended to provide a safe, economical, and less distressing method to monitor compartment syndrome.

The spectral functions are studied in conjunction with the dyadic Green's functions for various media. The dyadic Green's functions are found using the eigenfunction expansion method for homogeneous, inhomogeneous, periodic, lossless, lossy, and anisotropic media, guided by the Bloch-Floquet theorem. For the lossless media cases, the spectral functions can be directly related to the photon local density of states, and hence, to the electromagnetic energy density. For the lossy case, the spectral function can be related to the field correlation function. Because of these properties, one can derive properties for field correlations and the Langevin-source correlations without resorting to the fluctuation dissipation theorem. The results are corroborated by the fluctuation dissipation theorem. An expression for the local density of states for lossy, inhomogeneous, and dispersive media has also been suggested.

In this paper, a dual notch Ultra Wideband (UWB) monopole antenna with compact dimensions of 37.8×27.1×1.6 mm³ is presented. Octagon patch with defected ground structure is used to attain the wide frequency range of 3.17 GHz-11.61 GHz with ultra-wide impedance bandwidth of 8.33 GHz. The band notch characteristics in WiMAX (3.2 GHz-3.67 GHz) and WLAN (4.32 GHz-5.81 GHz) bands are achieved using inverted pi-slot in the radiating element and a pair of double split ring resonators (DSRRs) on either sides of the feed respectively. Reconfigurability in the bands is obtained by using BAR64-02 pin diodes switching at the appropriate placement in the antenna structure. The proposed antenna exhibits efficiency of 88% in operating and 20% in non-operating frequencies. The proposed antenna is designed, simulated and optimized using HFSS 19 electromagnetic tool. The measured results are tested using combinational analyzer in chamber with antenna measurement setup for validation and found in good matching with simulation.

In this article we theoretically investigate the visible extinction efficiency that can be obtained using a two dimensional particle. We show that extinction efficiencies up to the upper limit can be obtained from two dimensional particles (thin circular disks or flakes) compared with one dimensional (fibers) and three dimensional particles (spheres). Features of the theory of electromagnetic extinction by thin circular disks are thoroughly investigated for wide size and material contents parameters in the visible. The results of this article are of importance for the search of efficient aerosol attenuative candidates in the visible spectral region.

In this paper, a compact Giuseppe Peano, Cantor Set and Sierpinski Carpet fractals based hybrid fractal Antenna (GCSA) is designed and developed for Industrial, Scientific and Medical (ISM) band applications. The proposed GCSA is a hybrid fractal design which is created by fusing Giuseppe Peano, Cantor set and Sierpinski carpet fractals together. The optimization of the microstrip line feed position is performed by using a Firefly Algorithm (FA). The substrate material employed for proposed GCSA is a low-priced, easily available FR4 epoxy of thickness 1.6 mm. By varying the geometrical dimensions of the radiating patch, a data set of 58 GCSAs is randomly generated for the realization of Artificial Neural Network (ANN) and FA approaches. The designed structure is fabricated and then measured results are evaluated. The proposed GCSA is capable of resonating at 2.4450 GHz with S(1,1) < -10 dB. The measured bandwidth of the operating ISM band is 101 MHz. The quantitative performance of three different ANN types reveals that Feed Forward Back Propagation ANN (FFBPN) shows minimum error in comparison to other two ANN types. The simulated, experimental and optimized results show a good match that specifies the preciseness of the measurement.

In this research, the potential of L-band SAR data is evaluated for tropical peatland forest biomass estimation using polarimetric features and field data. For this, ALOS-2 full polarimetric data are acquired over central Kalimantan, Indonesia. Total 54 sampled plots (20 m x 20 m) were established in the study site; diameter at breast height (DBH) and tree species of every tree were collected in each plot. Locally developed allometric equations were used to convert field data to biomass and plot level biomass, and the upscaling factor was applied to upscale plot level biomass to standard tones per hectare scale. Backscattering coefficient (σ_o) was computed for HH, HV, VH and VV polarization. Similarly, eigen decomposition was performed to extract: entropy (E), alpha (α), and anisotropy (A); also diversity indices were computed. Yamaguchi decomposition was performed to extract scattering behavior of forest in central Kalimantan. All polarimetric parameters were upscaled to one-hectare scale. Field data were divided into training plots (70 percent → 42 plots) and validation plots (30 percent → 12 plots). Nonlinear regression analysis was performed between polarimetric parameters and training plots. Perplexity, Shannon index, entropy, Gini Simpson index, index of qualitative inversion, Reyni entropy (order 2), σ_HV, alpha, σ_VV, and volumetric scattering component were found significantly correlated (ranging R² from 0.67 to 0.49) with the field data. The corresponding nonlinear model was inverted, and biomass maps were computed for the individual model. The resultant biomass maps were validated using validation set of referenced measurements. Perplexity, Shannon index, entropy, Gini Simpson index, index of qualitative inversion, Reyni entropy (order 2), σ_HV, alpha, σ_VV and volumetric scattering exhibited a significant correlation between field biomass and predicted biomass computed using developed model. R² for validation ranges from 0.95 to 0.81 with RMSE ranging from 13.59 Mgha^-1 to 25.63 Mgha^-1. The estimated biomass in study site ranges from 49.31 Mgha^-1 to 290.60 Mgha^-1.

Wide bandwidth and high gain designs of sectoral microstrip antennas gap-coupled with parasitic arc shape patches are proposed. In 1800 MHz frequency band, optimum response with bandwidth of more than 50% and peak gain of 10 dBi is obtained for 30° sectoral angle employing two gap-coupled arc shape patches. Further gap-coupled variations of slot cut single arc shape patch with 60° sectoral patch is presented. This design yields bandwidth of above 930 MHz (~53%) with peak gain of more than 10 dBi. The comparison for the proposed gap-coupled sectoral variations with reported antennas is presented. Proposed gap-coupled sectoral configurations are single layer and thus simple in design and yet offers bandwidth and gain of larger than 50% and 10 dBi, respectively.

Tunneling of microwave radiation through a symmetrical trilayer ENG-ferrite-ENG is considered, where ENG refers to a medium of negative permittivity. Such trilayer is an example of a magnetically controlled structure that under certain conditions allows a complete (or perfect) tunneling of the incident radiation. In this paper, the general conditions of the perfect tunneling are analyzed, and the transmissive properties of the structure are studied numerically. It is demonstrated that a broad passband, in which the structure is almost completely transparent, may be obtained both above and below the frequency of the ferromagnetic resonance. The bandwidth can be effectively controlled by an external field that is magnetizing the ferrite layer.

A reconfigurable antenna with on-demand single-band or dual-band rejection capability for ultra-wideband (UWB) applications is presented. A modified monopole structure is integrated with a U-shaped slot and an open-ended slot to realize band-rejection. The antenna operates in four modes: a full UWB (3.1-10.6 GHz) coverage antenna, a UWB antenna with a single-band WiMax or wide local area network (WLAN) rejection, and a UWB antenna with dual-band WiMax/WLAN rejection. On-demand single and dual-band rejections are implemented by controlling two slots using two PIN diodes. Thus, the adopted control technique is quite easy and requires low operating power. Details of the design process and reconfiguration mechanism are presented. The band-rejection performance is explained by return loss and surface current distribution at single-band mode. A prototype is built on a Rogers substrate and tested to validate the performances. The antenna exhibits stable radiation characteristics and almost flat gain responses across the whole band, while significantly gain reduction is achieved at the rejected bands. Therefore, this antenna is suitable for high-performance UWB systems in WiMax/WLAN dense environments with the aim to improve signal quality, system capacity, and communication efficiency.

In this paper 8000 rpm generators with the magnetic cores made of amorphous low-coercivity material and electrotechnical steel were designed. The sizes of the magnetic cores of generators were calculated analytically. Computer simulations of the generators under study were carried out to obtain a complete pattern of the magnetic field distribution in the magnetic cores and to estimate the generator losses. Experimental models of the generators were also made, which were studied at no load and with load. A special bench with a torque sensor was used for experimental studies.

In this paper the design of asymmetric wideband printed dipole antenna is presented along with measured results. The wide bandwidth covering 0.8-4 GHz is achieved using inset feeding technique. This paper also presents the techniques for achieving good omni-directional radiation patterns over the wide frequency band with deviation from omni-directionality within ±2.5 dB. This design offers more than 5:1 impedance bandwidth (for VSWR≤2.2:1), with good radiation efficiency and omni-directionality. The comparison study of symmetrical and asymmetrical printed dipole antennas with and without inset feed is presented in this paper. Thus, the proposed antenna finds a wide range of applications in trans-receive modes in today's wireless devices.

In the development of hand gesture based Human to Machine Interface, the Doppler response feature extraction method plays an important role in translating hand gesture of certain information. The Doppler response feature extraction method from hand gesture sign was proposed and designed by combining time and frequency domain analysis. The extraction of the Doppler response features at the time domain is developed by using cross correlation, and the time domain feature is represented by using peak value of cross correlation result and its time shift. The Doppler response feature of frequency domain is extracted by employing a discriminator filter determined by the frequency spectrum observation of Doppler response. The proposed method was employed as a pre-processing for Continuous Wave (CW) radar output signals, which is able to relieve the pattern classification of Doppler response associated with each hand gesture. The simulation and laboratory experiment using HB 100 Doppler radar were performed to investigate the proposed method. The results show that the combination of all three features was capable of differentiating every type of hand gestures movement.

Regarding the increasing application of terahertz technology, the interest in using two-wire waveguides is getting more and more popular due to their favorable propagation properties. Therefore, a more accurate analysis of these structures is very important. In this paper, a simple analysis of the guided waves in a two-wire waveguide based on Bipolar Coordinate System (BCS) has been investigated. The structure under study is two infinite perfect electric conductor (PEC) cylinders in z direction, whose axes are positioned at a distance d from each other. The solution of TE and TM modes is sought by the aid of electromagnetic formulation, and an analytical expression is proposed for electromagnetic fields and cutoff wave numbers, which have not been present in any of the previous studies. In this study, for the first time a BCS has been used to formulate two-wire waveguide problem, and the validity range of the answer is discussed. The values of the cutoff wave numbers are calculated for the first few modes of TE and TM, using both the proposed method and Finite Difference Method (FDM). The precise correspondence of the obtained values with the proposed method with those of FDM, along with the high speed and simplicity in implementation, introduces the present method as an appropriate candidate for analyzing transmission lines using parallel cylinders.

In this paper, the implementation of convolution perfectly matched layer (CPML) with good absorbing property is proposed for the symplectic multi-resolution time-domain (SMRTD) method, and a side-wall vault-top tunnel model is established by using the equidistant equation. The radian of the tunnel can be selected in the range of 0-π/2 according to actual needs. The absorbing performances of perfect matched layer (PML) and CPML are compared in the proposed tunnel model. In addition, based on the straight tunnel model and curved tunnel model with different radians, the characteristic of field cross-section distribution of electromagnetic pulse (EMP) propagation excited by TE₁₀ mode is studied.

This paper presents the first coupled-line coupler that provides independent power division ratios at dual bands. In contrast with previous dual-band coupled-line couplers, the power division ratios k²(f₂) and k²(f₂) at each band (f₁ and f₂) can be independently controlled in order to satisfy the requirements of various communication protocols at different bands. Moreover, it has a compact size due to the usage of coupled lines rather than transmission lines. Explicit design equations and design guide of the coupler are provided. In this letter, one prototype of the proposed coupler is simulated, fabricated, and measured. It provides power division ratios k²(f₁)=4 dB at f₁=1 GHz and k²(f₂)=8 dB at f₂=2.4 GHz. The measured result agrees well with the simulation.