This work studies the influence of material coatings, especially combined natural and metamaterials, on the radiation properties of a practical dipole like antenna, represented by a slotted conducting sphere. The selected geometry allows an exact solution to the problem, and thus the development of exact expressions for the antenna parameters, like the radiated power and directivity. It is shown that for materials with combined positive and negative parameters, mode resonances can occur at thinner coatings, the thickness of which can be made diminishingly small by proper selection of coating parameters. In particular, at these resonances the antenna directivity, while being finite, becomes independent of the antenna size and coating parameters.

Considering Radio Frequency (RF) heating as a viable alternative for the in-shell heating of eggs, Finite Element Modeling and simulation of RF heating of in-shell eggs at 27.12 MHz were carried out to assess the feasibility and heating uniformity of the process. According to the recommendations of USDA-FSIS for the pasteurization of eggs, egg white must be heated up to 57.5°C, and the egg yolk has to be heated up to 61.1°C for 2 min. The objective of the simulation was to determine the locations of hot and cold spots generated due to non-uniform heating. A parallel plate setup for Radio Frequency heating was simulated for different electric field strength levels and orientations of the egg (long axis parallel and long axis perpendicular to the plates). The simulation results were experimentally verified and the simulation procedure was validated using a laboratory parallel plate RF setup. A coaxial cavity design was simulated with a similar approach. Results indicated that both the parallel and coaxial cavity designs were suitable for in-shell pasteurization of eggs provided that the eggs were rotated to maintain the uniformity in heating. After the simulation of RF heating process, the process optimization was carried out to determine the most effective procedure for the process. The varying parameters obtained by using different modeling techniques for radiofrequency heating of in-shell eggs, were optimized using MATLAB. Laboratory scale experimental trials were conducted to test the validity and effectiveness of the optimized parameters. The optimal parameters set forth were found to be more efficient in terms of heating time and uniformity.

In this paper, we investigate the impact of beamforming (BF) on a multi-antenna two hop amplify-and-forward (AF) fixed gain relay network over Rician-Rayleigh and Rayleigh-Rician asymmetric fading channels, respectively. The network consists of a relay with single antenna used to assist the signal transmission from the source to the destination, both of which are equipped with multiple antennas. By using the channel state information (CSI), the maximal output signal-to-noise ratio (SNR) with optimal beamforming is first obtained. Then, the novel analytical expressions for the outage probability (OP), probability density function (PDF) and generalized moments of the maximal output SNR are derived. Moreover, the theoretical formulas of the Ergodic capacity and average symbol error rates (ASERs) with various modulation formats are also developed. To gain further insights, the asymptotic ASERs at high SNR are presented to reveal the diversity order and array gain of the multi-antenna relay network. Finally, computer simulations confirm the validity of the theoretical analysis and indicate the influence of antenna number and Rican factor on the system performance.

Reverberation chamber (RC) test facility allows to determine the absorbing cross section (ACS) of lossy materials under a random field excitation. Measurements are based on the quality factor variation produced by the sample under test presence with respect to the empty chamber condition. Simulations are based on the representation of the RC electromagnetic field by means of a random plane wave superposition. A finite-difference time-domain code is used to compute the material absorbed power and to recover a numerical ACS. The method sensibility is stressed by application to small size samples. Comparison between numerical and experimental data reveals a satisfactory agreement. Results for different materials are presented in the paper: soft foam absorbers, carbon foam sheets, and carbon/carbon sheets.

Our work investigates the well-known Lorentz formula (in its original form) for the EM force. It allows the prediction of one effect of the action of the EM force on a moving charge. We use this effect to explain Tesla's mechanism of wireless power transfer between resonant coils.

A new shape of ultra-wideband antenna with a measured bandwidth of 122.67% is presented in this paper. The proposed antenna has fabricated on Duriod 22 × 41 mm² substrate and tested. The simulated and measured return loss results which have been presented in this paper indicate the antenna operates between 2.9 to 12.1 GHz frequency bands. In order to increase the bandwidth of aforementioned antenna, a unique shape of the ground plane has been proposed. This shape of ground plane has a very important role not only on increasing the bandwidth but also for removing some unwanted ripples from the return loss results.

An extrinsic Fabry-Perot cavity in optical fiber is used to achieve surface imaging at infrared wavelengths. The micro-cavity is realized by approaching a single mode fiber optic with a numerical aperture NA to a sample and it is fed by a low-coherence source. The measurement of the reflected optical intensity provides a map of the sample reflectivity, whereas from the analysis of the reflected spectrum in the time/spatial domain, we disentangle the topography and contrast phase information, in the limit of nearly homogeneous sample with complex permittivity having Im(ε) << Real(ε). The transverse resolution is not defined by the numerical aperture NA of the fiber and consequently by the conventional Rayleigh limit (about 0.6λ/NA), but it is a function of the transverse field behavior of the electromagnetic field inside the micro-cavity. Differently, the resolution in the normal direction is limited mainly by the source bandwidth and demodulation algorithm. The system shows a compact and simple architecture. An analytical model for data interpretation is also introduced.

In this manuscript, a simple synthesis method of single square loop frequency selective surface (SSLFSS) is discussed, which may find the suitable application in the fast analysis and fabrication of the frequency-selective surface. The presented technique is used to design SSLFSS at 3 GHz, 15 GHz, 22 GHz and 26 GHZ. At every frequency of interest, the analytical result is very close to the required result. Moreover, a way to control the reflection at any frequency is discussed, which may find an application in controlling the reflection level at any frequency. However, we have proposed two simple, cheaper and lightweight structures at 3 GHz and 22 GHz for the application in various satellite communications. The proposed process has been extended to the analysis of bandpass structure and desired results have been achieved, which indicates the utility of the method of synthesis of both the bandpass and bandstop structures.

In this paper, 4G smart planar dual-band phased array antenna suitable for fourth generation (4G) Long Term Evolution (LTE) and also Wireless Local Area Network (WLAN) systems is developed. The proposed planar array antenna is built using a microstrip rectangular U-slotted patch antenna element. Single element and linear sub-arrays with 1 x 2 and 1 x 4 dimensions of this element are designed, fabricated, and measured by the same authors. Separate feeding technique is used for each element of the smart planar array antenna; such that full beam-shaping can be achieved by steering the pattern main-loop to different angles in both azimuth and elevation directions with different amplitudes. Beam steering up to ±22 degrees can be achieved in both azimuth and elevation direction at 60 degrees phase shift without the presence of any grating lobes. At this value of phase shift, the gain is 22.62 dBi without changing in the mutual coupling. This is also suitable for 4G Multiple-Input Multiple-Output (MIMO) wireless mobile applications with reduced power consumption. Design simulation and optimization processes are carried out with the aid of the Agilent Advanced Design System (ADS) electromagnetic simulator that uses the full-wave Method of Moment (MoM) numerical technique.

This article presents a novel technique for isolation enhancement between two closely packed antennas. First, an inverted-U loop antenna (IULA) integrated into the top edge of a laptop panel is designed for 2.6-GHz LTE application. The mutual coupling between two designed IULA antennas has considerable effects by the placing positions of them. The results indicate the ground of the two IULA antennas placing against each other obtain the best isolation. At last, a three-element MIMO antenna was designed and measured. Although the gap between two adjacent antennas is only 1 mm, the experimental results show that the proposed two-element and three-element MIMO antennas achieve more than 20 dB isolation within the operating band. The important performances of antenna efficiency, envelope correlation, and channel capacity are also presented.

In this paper, a novel planar array antenna for multi-band linear polarization discrimination is proposed. The proposed array antenna consists of 12 patch elements and a double-balanced multiplier. A slot-ring and four diodes used in the multiplier also act as an antenna and amplitude detector, respectively. Furthermore, slot lines which are parts of feeding circuits also act as slot antennas. The Both-sided MIC technology is effectively employed to realize the feeding circuit which eliminates the extra impedance matching circuit. The array antenna is realized in a very simple and compact structure as all the antenna elements, feeding circuit and the multiplier/amplitude detector are arranged on both sides of a substrate. The proposed array antenna can discriminate ±45° linear polarization in three frequency bands. The ability of the proposed array antenna to discriminate orthogonal linear polarization is successfully confirmed in C and X band by the experimental investigation.

Based on the Composite Right/Left-Handed (CRLH) Transmission Line (TL) approach this paper presents a 3-band T-Junction power divider. The proposed design strategy uses a stub-loaded TL for the right-handed portion of the line; this way, with respect to a conventional CRLH line, one more degree of freedom is available. Experimental and numerical results referring to a prototype using surface-mount capacitors and inductors are reported and discussed. It is demonstrated that the artificial transmission line (ATL) here presented is an optimum candidate for designing high-added value microwave devices. Furthermore, based on the use of metal-insulator-metal capacitors and short circuited stubs, a monolithic implementation is also proposed.

The Remote Field Eddy Current (RFEC) method is widely used to inspect both ferrous and nonferrous metal tubes when internal access is the only possible way of inspection. An axisymmetric quasi-analytical model is presented in this paper in order to simulate the behavior of a RFEC system during its operation. The proposed model, based on the application of the Fourier Transform in space, is able to take into account the finite length of the excitation coil, fed by an AC current, and the relative movement between the RFEC system and the wall tube. Numerical simulations based on integral formulations and experimental measurements were used to validate the proposed quasi-analytical model.

Surface plasmon resonance effects on a system consisting of the double-chain silver nanorings are numerically investigated by means of the finite element method with three-dimensional calculations. The numerical results for resonant wavelengths corresponding to different light polarizations, pair numbers, illumination wavelengths, charge distribution and the permittivities filled inside the dielectric holes are reported as well. Results show that the double-chain silver nanorings exhibit tunable plasmon resonances in the near field zone that are not observed for the silver nanodisks of the same volume. The resonance wavelength is redshifted as the filling medium in dielectric holes increases, which is attributed to a longer effective optical path. It can be verified that the proposed structure (e.g., twelve pairs or more pairs) is pertinent to the functionality of long range of wave guiding and also show promise for applications in nanooptical devices, sensing, and surface-enhanced spectroscopy, due to their strong and tunable plasmon resonance.

Singular value decomposition and information theoretic criterion based clutter reduction is proposed for ground penetrating radar imaging. The scheme is capable of discriminating target, clutter and noise subspaces. Information theoretic criterion is used with conventional singular value decomposition to nd target singular values. Proposed scheme works also for extracting multiple targets in heavy cluttered images. Simulation results are compared on the basis of mean square error, peak signal to noise ratio and visual inspection.

We consider the benchmark problem of magnetic energy density enhancement in a small spatial region by varying the shape of two symmetric conducting scatterers. We view this problem as a prototype for a wide variety of geometric design problems in electromagnetic applications. Our approach for solving this problem is based on shape optimization and isogeometric analysis. One of the major difficulties we face to make these methods work together is the need to maintain a valid parametrization of the computational domain during the optimization. Our approach to generating a domain parametrization is based on minimizing a second order approximation to the Winslow functional in the vicinity of a reference parametrization. Furthermore, we enforce the validity of the parametrization by ensuring the non-negativity of the coefficients of a B-spline expansion of the Jacobian. The shape found by this approach outperforms earlier design computed using topology optimization by a factor of one billion.

This paper presents a low-cost pattern-reconfigurable microstrip antenna. The proposed design strategy uses a slotted patch antenna on a bi-layer structure as basic element of a switched parasitic array. Reconfigurability is obtained by means of PIN diodes used to vary the resonance frequency of the parasitic patches. Experimental results referring to a prototype consisting of an array of three elements optimized for the Ultra High Frequency (UHF) band of Radio Frequency IDentification (RFID) systems are presented and discussed. It is demonstrated that the proposed antenna exhibits a main beam that can be reconfigured into three different directions.

We derive an expression for the torque exerted on an electric/magnetic dipole moving in an electromagnetic field, which contains two new velocity-dependent terms that to our knowledge were not reported before. A physical meaning of various torque components is discussed in terms of Lorentz force law and hidden momentum contribution.

In this paper, a partial coherent approach is used to study the third and fourth Stokes parameters in passive microwave remote sensing of Sastrugi snow surface over layered snow structures. The incoherent part of the model consists of using radiative transfer theory for the snow layers. The coherent part of the model is using numerical solutions of Maxwell equations to derive the bistatic scattering and transmission coefficients of conical scattering by sastrugi surfaces which have large heights and large slopes. We then use the rough surface boundary conditions of conical scattering from the coherent part, in the incoherent radiative transfer equations. The radiative transfer equations are then solved iteratively that includes multiple interactions between the layered structures and the rough surfaces. Simulation results indicate that large third and fourth Stokes parameters are obtained because of the coupling of large angle transmissions of the rough surfaces with the internal reflections of layered structures. The partial coherent approach also eliminates the coherent interference patterns in angular variations from multiple reflections of layer boundaries that were present in the fully coherent approach.

In this paper a novel broadband quadrature power divider and its robust design method are presented. The QPD consists of a two-section power divider in combination with a 90-degree differential phase shifter. The two-section power divider is calculated to provide equal power split, high output port isolation, and good return loss at all three ports. The differential phase shifter consists of a composed right/left handed transmission line and pure-right handed transmission line named CRLHu-TL and PRHd-TL, respectively. The CRLHu-TL is divided into two parts; one of them consists of a pure-left handed section whose parasitic pad effects are represented by means of a pure right handed section named PRHp. On the other hand, the PRHd-TL is composed by a microstrip transmission line of characteristic impedance 50Ω and electrical length 50° and two sections equivalents to PRHp. The proposed circuit is applied to develop a broadband balanced amplifier with measured fractional bandwidth (FBW) of 124.4% at the center frequency of 2 GHz.