The electromagnetic plane wave diffraction by the half-plane with fractional boundary conditions is considered in this article. The theoretical part is given based on that the near field, pointing vector and energy density distribution are calculated for different values of the fractional order. The results are compared with classical cases for marginal values of the fractional order. Interesting results are obtained for fractional orders between marginal values. Results are analyzed.

This paper presents a technique to design a very small planar antenna for ultra-wideband (UWB) communication applications. To cover UWB frequency range by a small-size antenna, the ground plane influence on the antenna impedance bandwidth is suppressed at middle and higher frequencies. To accomplish this purpose, a rectangular and several stepped slots are etched on the conventional radiator. Also, a tuning stub is printed in the rectangular slot, and its length is optimized. This technique decreases current distribution on the ground plane at higher frequencies, and the impedance matching of the antenna is significantly influenced by the radiating patch. The antenna has a compact size of 25 × 25 × 1.6 mm³. It can provide a wide impedance bandwidth from 2.8 to 15.4 GHz (|S₁₁| < -10 dB) which covers the entire UWB spectrum (3.1-10.6 GHz). Two prototypes of the antenna were fabricated and measured. The impedance matching, group delay, fidelity factor, and the antenna radiation characteristics, including co- and cross-polarized far-field patterns and realized gain were analyzed with numerical simulation and experimental measurement. Measured data are in good agreement with the simulated ones. Based on the obtained frequency- and time-domain characteristics, the designed antenna is an excellent candidate for UWB wireless devices.

In this paper, the investigation about a metal-insulator-metal (MIM) compound plasmonic waveguide is reported, which possesses the transmission property of plasmon induced transparency (PIT) and exhibits the potential application of refractive index sensing. The waveguide structure consists of an MIM-type bus waveguide, a horizontally placed asymmetric H-type resonator (AHR), and a circular ring resonator (CRR). The AHR is directly coupled with the bus waveguide, whilethe CRR is directly coupled to the AHR, but is indirectly coupled to the bus waveguide. Due to the destructive interference between two different transmission paths, PIT effect can be observed in the transmission spectrum. The finite element method (FEM) is used to study the PIT effect in detail. The results show that the transmission characteristics can be flexibly adjusted by changing the geometric parameters of the structure, and the proposed waveguide structure has potential application prospects in the area of temperature and refractive index sensing with higher sensitivity, better figure of merit, and in the area of slow light photonic devices.

In this communication, a new planar monopole ultra-wideband (UWB) antenna with quad notched band characteristics using quad-mode stepped impedance resonator (QMSIR) is investigated. The proposed antenna is composed of a circular-shaped radiating element, a 50 Ω microstrip feed line, a QMSIR, and a partially truncated ground plane. By coupling a QMSIR with an additional outer line beside the microstrip feedline, band-rejected filtering properties around the (5.2/5.8 GHz) WLAN bands and the (7.4/8.2 GHz) satellite communication bands are generated. The measurement of voltage standing wave ratio (VSWR) is in agreement with simulation. The results show that proposed antenna not only retains an ultra-wide bandwidth but also owns quad band-rejections capability. The UWB antenna demonstrates omnidirectional radiation patterns across nearly whole operating bandwidth that is suitable for UWB applications.

Millimetre-wave thermography is used to image through the soles of shoes as proof of principle study into the application of such an approach for security inspection. Current airport security screening practice necessitates the removal of shoes prior to x-ray screening for potential threats or other concealments, for example explosive or explosive precursor materials; narcotic substances or small weapons. The authors demonstrate that thermography at ~250 GHz is able to reveal a variety of objects concealed within the soles of typical shoes, and that such an approach might be applied to rapidly screen passengers without necessitating the removal of their footwear.

A new structure design of a multi-band suspended stepped slot microstrip patch antenna with copper ground plane for future mobile communications is proposed and presented. A parametric study for the effect on the proposed antenna is done on a par with the integration of a polycrystalline silicon solar cell. The compact low profile proposed antenna is developed using Printed Circuit Board (PCB) technology on a substrate, FR4 with physical size of 50×50 mm². Simulated and measured results are presented to validate the usefulness of the proposed antenna structure for Wi-Max and future mobile communications. The measured result reveals that the presented stepped slot patch antenna with copper ground plane offers impedance bandwidth of 3.94% (covering 5.46 GHz-5.68 GHz band), 3.06% (covering 7.08 GHz-7.3 GHz band), and 9.26% (covering 8.34 GHz-9.15 GHz band). The same radiating patch with solar ground plane offers impedance bandwidth of 4.58% (covering 5.12 GHz-5.36 GHz band) and 3.06% (covering 7.32 GHz-8.02 GHz band) for future mobile communications. Good VSWR and radiation pattern characteristics are obtained in the frequency band of interest.

The design, analysis, and manufacturing of an oversized circular metallic corrugated waveguide with rectangular and square grooves for transmitting power from gyrotron to tokamak or dummy load have been carried out. To carry high power at millimeter wave with lower transmission loss, a corrugated waveguide is preferred. A corrugated waveguide with HE₁₁ mode gives lower attenuation than a smooth circular waveguide with TE₁₁ mode. The theory behind the depth and width selection of corrugations required to carry the linearly polarized (HE₁₁) mode is explained in this paper. The proposed structures are designed and simulated in CST microwave studio software. Rectangular and square groove circular corrugated waveguides each having a length of 500\,mm were fabricated and tested using ZVA50 vector network analyzer. Based on the performance results, it is derived that the square groove corrugated waveguide gives lower insertion loss of 0.08 dB/meter than rectangular groove corrugated waveguide which gives insertion loss of 0.11 dB/meter.

In this work we describe a model for the computation of the scalar and vector potentials associated with known electric and magnetic fields, as well as for the inverse problem. The formulation is general, but the applications motivating our study are related to the requirements for advanced modeling of charged particle dynamics in plasma-driven electromagnetic environments. The dependence of the electromagnetic field and its potentials in space and time is assumed to be separable, where the spatial part is connected to established solutions of the static problem, and the temporal part is derived from a phenomenological description based on time-series of measurements. We benchmark our model in the simple problem of a finite current-carrying conductor, for which an analytical solution is feasible, and then present numerical results from simulations of a magnetospheric disturbance in geospace.

In this paper, a periodic interdigital structure for wideband mitigation of differential-to-common mode conversion at the bend discontinuity of differential lines is proposed. A hybrid inductance and capacitance compensation property is exhibited to suppress the common-mode noise of asymmetric transmission lines. An equivalent circuit model is given to explain the working principle of the presented periodic interdigital structure for differential pairs. In comparison with the traditional methods, steep and wideband suppression performances are both observed with the proposed design. Moreover, no additional area is required at the bend discontinuity for compensation. From the measured result, the differential-to-common mode conversion of the differential signals can be mitigated from DC to 10 GHz with a rejection level of -20 dB. The measurements agree well with the simulation predictions.

The reaction concept, introduced by Rumsey in 1954, describes interaction between time-harmonic electromagnetic sources through the fields radiated by the sources. In the original form the concept was a scalar quantity defined by three-dimensional field and source vectors. In the present paper, the representation is extended to four dimensions applying differential-form formalism. It turns out that, in a coordinate-free form, the reaction concept must actually be a one-form, whose temporal component yields Rumsey's scalar reaction. The spatial one-form component corresponds to a three-dimensional Gibbsian-vector reaction which consists of electromagnetic force terms. The medium is assumed homogeneous and isotropic in this paper.

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.