In this paper, we present the extraction for effective material parameters for a metamaterial from TE or TM waveguide measurements with generalized sheet transition conditions (GSTCs) used to provide electric and magnetic surface susceptibilities that approximate boundary effects between the metamaterial and air. The retrieval algorithm determines the effective material properties via scattering data obtained from the metamaterial in a waveguide. The effective refractive index is expressed as a function of S-parameters for two samples of different length. The effective wave impedance is given in terms of $S$-parameters and the refractive index, assuming that GSTCs account for the boundary effects. The effective permittivity and permeability can then be determined through the refractive index and wave impedance. By use of S-parameters generated by commercial three-dimensional (3-D) full-wave simulation software our present equations are tested for two cases of metamaterials: magneto-dielectric (ε_r=μ_r) and dielectric (TiO₂) particles. We also conduct S-parameter measurements on dielectric cubes with an S-band (WR-284) waveguide to compute the effective material properties. Furthermore, our results are compared to those derived from another retrieval method used in the literature, which does not account for boundary effects.

In this communication, a new compact UWB monopole antenna with dual band rejection is presented. The antenna is designed using FR4 substrate with dielectric constant 4.4, loss tangent 0.02 and a height of 1.59 mm. Initially the UWB antenna is designed to obtain a 153% fractional bandwidth from 2.4 GHz-21.7 GHz. The ground plane beneath the patch is etched out and a rectangular slot is introduced to obtain a broadband matching over the operating frequency range. Later the antenna is modified to get a frequency notch in the IEEE802.11a and HIPERLAN/2 WLAN operating band (5.15 GHz-5.825 GHz) to avoid potential interference. A U shaped slot is optimally introduced in the patch to get the desired performance. Finally an L shaped slot is cut from the radiating patch to filter the frequency band 3.3 GHz-3.6 GHz, which is WiMAX service band. The antenna parameters are optimized and the effects of parametric variation on antennas performance are studied and the summary is presented. The antenna is fabricated and measured results are presented. The measured results are in well agreement with the simulated results.

The subject of this article is to optimize the design of synchronous reluctance machines with massive rotor and multi-flux barrier rotor. The optimization procedure, which aims to improve simultaneously the machines' torque and the power factor, uses the cyclic coordinate method coupled with the magnetostatic finite-element (FE) field solutions. The optimization results regarding these two types of machines, which provide the optimized rotor geometrical dimensions and the influence of the current angle, are discussed.

Electromagnetic radiation by dipole antenna loaded with general bi-isotropic objects is investigated using time-domain integral equations. By introducing pairs of equivalent electric and magnetic sources, electromagnetic fields inside a homogeneous bi-isotropic region can be represented by these sources over its boundary. A series of coupled surface integral equations are obtained after imposing boundary conditions. These equations are solved numerically by the Galerkin's method that involves separate spatial and temporal testing procedures. The scaled Laguerre functions are used as the temporal basis and testing functions. The use of the Laguerre functions completely removes the time variable from computation, and the results are stable even at late times. Numerical results are presented and compared with analytical results, and similarities and differences are observed.

This research proposes a new blind tracking algorithm for smart antenna arrays by switching the main beam iteratively using the cost calculated from the received and predicted symbol. This algorithm will be called Cost Steering Algorithm Using Demodulation-Remodulation Technique COSTAUS/DRT. It is completely independent of the Least Mean Squares (LMS) or any derived version from it, and it does not need to investigate the cyclostationary properties of the incoming signal. A complete derivation and analytical model with simulation using Simulink is given in this research. The algorithm was tested under three different target motions which are a triangular motion (linear), sinusoidal motion (circular) and saw tooth motion which is an adverse case when the linear motion changes its path suddenly. The transmitter uses 16-level PSK signal with no Forward Error Correction code (FEC) in order to test the algorithm under the worst situation. The algorithm is tested under different noise power levels. The antenna array is a linear array with 16-elements.

By introducing bistatic geometry to near range microwave imaging systems, this paper proposes a near range three dimensional (3D) bistatic imaging geometry based on planar scanning aperture and establishes corresponding echo model. Then, the paper deduces the 3D bistatic Omega-K imaging algorithm based on implicit spectral decomposition, in which the impacts of residual phase, including position displacement, range, azimuth and elevation defocusing, are analyzed and compensated. Finally, the 3D bistatic imaging geometry and algorithm are investigated and verified via numerical simulations and experiments using a near range imaging system.

In this paper, time-domain physical optics (TDPO) method is extended to its iterative version (TDIPO) to consider the coupling effects between two regions, and the latter is employed to investigate electromagnetic scattering from three dimensional target half-buried by a two dimensional rough surface. By using iterative scheme, more accurate transient response reflected from combinative target with multi-scattering effects would be obtained than that by using TDPO alone. The TDIPO could also be enhanced by time-domain equivalent edge current (TDEEC) to further determine the far-field characteristics of the combinative target with rough surface. An accurate composite geometry model technique which combines 2D perfectly electrically conducting (PEC) rough surface and half-buried 3D PEC target is introduced and employed to assist the meshing work. The validity of the presented method is verified by comparing the scattering results for dihedral targets with those obtained through TDPO and finite difference in time domain (FDTD), as well as multi-level fast multiple algorithm (MLFMA). Then simulations of EM scattering from the target embedded in rough surface for different incidence directions are carried out to test the availability of TDIPO/EEC. Discussions on the effects of incidence direction and the presence of the target on the backscattering in far-zone are also given.

Many algorithms exploiting the signal cyclostationarity have been shown to be effective in performing antenna array beamforming. However, these algorithms can not provide a unique weight vector for simultaneously extracting multiple signals of interest (SOIs) with distinct cycle frequencies (DCFs). They also suffer from severe performance degradation in the presence of a cycle frequency error (CFE). To simultaneously accommodate multiple SOIs with DCFs and alleviate the effects of cycle leakage due to finite data samples, we propose a cyclic sample matrix inversion (C-SMI) beamformer. To make the C-SMI beamformer robust against CFE, we present a novel objective function which is optimized by using a steepest-descent based algorithm to find the appropriate estimates of the true DCFs. The simulation results show the effectiveness of the robust C-SMI beamformer.

The beamspace domain of parasitic antenna arrays is explored in this paper, providing the aerial degrees of freedom available for use in Multiple Input-Multiple Output (MIMO) systems. The beamspace representation allows for the design of an alternative MIMO architecture based on single radio-frequency (RF) chains, and facilitates the inclusion of MIMO transceivers in devices with strict size limitations. A three dimensional orthogonal expansion is performed on the beamspace domain providing the basis patterns used for mapping of the transmitted symbols and for sampling at the receiver. The expansion is based on the Gram-Schmidt orthonormalization procedure and can be generalized for any parasitic antenna array. The multiplexing capability of ESPAR antennas is presented as a means for supporting future performance demanding communication systems. Performance evaluation results are illustrated in detail.

Rain cell size is an input requirement for rain-induced attenuation studies. It is useful in estimating the extent of a given radio link path that will traverse the rain medium in a given rain event. The ``Synthetic Storm'' approach, which requires 1-minute integration time data, is used to derive the proposed rain cell sizes for various climatic zones within South Africa. The conversion of the readily available 1-hour integration time rain rate data to the desired 1-minute rain rate is carried out first for some locations and then validated by the existing measurement data and proposed global conversion factors. By the use of rain-induced attenuation prediction equation for terrestrial links that requires rain cell size as input, contour plots of specific attenuation for two high bandwidth frequencies used in terrestrial link implementations is presented. Site diversity separation distance map is proposed as well from the link budget analysis for each location to achieve an all time link availability of 99.99% of time.

This work presents a straightforward way to obtain the coupling matrix of a bandstop filtering response from the original bandpass coupling matrix. The generated bandstop coupling matrix implements a response where the bandwidth is defined at the equiripple return loss of the lower and the upper passbands.

We propose a cylindrical invisibility cloak achieved utilizing two dimensional split-ring resonator structured metamaterials at microwave frequencies. The cloak has spatially uniform parameters in the axial direction, and can work very well even when the cloak shell is very thin compared with the concealed object and the working wavelength. Numerical simulation is performed to verify the functionality of the cloak, where the cloak layer is only around 1/4 of the operating wavelength. Our work provides a feasible solution to the experimental realization of cloaks with ideal parameters.

This paper presents two full differential bandpass filters with small occupied areas. Both filters are designed with the same basic structure which consists of two double coupled resonators with magnetic coupling. The resonators are stacked up and have the advantage of high coupling efficiency, reducing the area. Nevertheless, in the basic structure, the insertion loss in the high stopband is above -10 dB and therefore does not meet the requirement for bandpass filter design. Thus, two solutions are introduced to form the proposed filters. The first one integrates the ground plane, while the second one makes the use of an extra transmission zero. With the help of these solutions, two types of full differential bandpass filters are implemented on an FR4 using the embedded passive device technology, with the additional purpose of being designed for SiP applications. The passband of the filters conforms to the WLAN IEEE 802.11a (5 GHz) standard. Most importantly, the occupied areas of the two proposed bandpass filters are only 6 mm х 6.7 mm and 6.6 mm х 8.3 mm respectively. Compared with previous research, area reductions of up to 98.05% and 97.76% can be achieved.

A technical challenge in hyperthermia therapy is to locally heat the tumor region up to an appropriate temperature to destroy cancerous cells, without damaging the surrounding healthy tissue. Magnetic fluid hyperthermia (MFH) is a novel, minimally invasive therapy aiming at concentrating heat inside cancerous tissues. This therapy is based on the injection of different superparamagnetic nanoparticles inside the tumor. In our study, superparamagnetic nanoparticles, which we developed and characterized, consisted of iron oxide nanoparticles stabilized with polyethylene glycol. Moreover, a new technique for MFH using a specially designed external electromagnetic waveguide as applicator is presented. Three magnetite concentrations were used for making the tumor phantoms, which were embedded in muscle phantoms. The phantoms were radiated and located at three different distances from the applicator. Furthermore, two volumes of tumor (2.5 mL and 5.0 mL) were assayed. Heating curves, as a function of time, allowed the establishment of a more appropriate nanoparticle concentration for obtaining the temperature increase suitable for hyperthermia therapy. The results shown in this paper confirm the feasibility of using nanoparticles as agents to focus the energy over the tumor, without creating hot spots in healthy tissue. In addition, the experiments validated that by using this applicator in combination with nanoparticles, it is also possible to locally control the increments of temperature in tissues.

The literature describing scattering matrices for semi-analytical methods almost exclusively contains inefficient formulations and formulations that deviate from long-standing convention in terms of how the scattering parameters are defined. This paper presents a novel and highly improved formulation of scattering matrices that is consistent with convention, more efficient to implement, and more versatile than what has been otherwise presented in the literature. Semi-analytical methods represent a device as a stack of layers that are uniform in the longitudinal direction. Scattering matrices are calculated for each layer and are combined into a single overall scattering matrix that describes propagation through the entire device. Free space gaps with zero thickness are inserted between the layers and the scattering matrices are made to relate fields which exist outside of the layers, but directly on their boundaries. This framework produces symmetric scattering matrices so only two parameters need to be calculated and stored instead of four. It also enables the scattering matrices to be arbitrarily interchanged and reused to describe longitudinally periodic devices more efficiently. Numerical results are presented that show speed and efficiency can be increased by more than an order of magnitude using the improved formulation.

The main goal of this paper is to present a design procedure for a flexible compact universal UHF RFID tag antenna suitable for worldwide UHF RFID applications. Systematic design procedure is introduced through the derivation of dipole input impedance general relation using induced EMF method considering wire radius effect. T-matched chart is used to match the tag input impedance with the chip input impedance and finally develop a flow chart to summarize the design procedure. The proposed antenna compactness trend is achieved through applying meandering and Franklin shape to conventional printed dipole antenna. Flexibility trend is achieved through using liquid crystal polymer LCP material as antenna substrate. The proposed antenna covers the frequency band 865 MHz to 1078 MHz and occupies an area of 1306.6 mm². The computed radar cross section RCS and conjugate match factor CMF insure that the proposed antenna structure is easily detectable and achieves acceptable matching level. Power reflection coefficient PRC is computed, measured and good agreement is obtained. Other antenna parameters such as radiation efficiency, gain and radiation pattern are also calculated. The proposed antenna is cheap, flexible and suitable for UHF RFID universal application.

The design and simplified analysis of a compact and wide band (16%) negative permittivity complementary split ring resonator metamaterial is introduced. The proposed metamaterial component was applied to reduce the size of the feeding line filter of microstrip patch antenna for the sake of higher order harmonic suppression. The reduction has been done using only one element of the complementary split ring resonator, while maintaining the antenna's performance. Simplified theoretical study and design of the proposed circuits has been presented. Moreover, experimental results have been done for validation and conformation purpose. Results confirm that almost 95% of the antenna noise harmonics power has been removed.

Cylindrical EBG structures excited by a Hertzian dipole source and TM polarized plane wave at oblique incidence are analyzed using a rigorous semi-analytical method based on the cylindrical Floquet mode expansion. Concentric and eccentric cylindrical EBG structures are investigated. Resonance and stopband characteristics in the transmission spectra of the cylindrical EBG structures, enhancement and shading effects in the excited fields, radiation patterns of Hertzian dipole located inside the cylindrical EBG structures in both H-plane and E-plane are numerically studied. Co-polarization and cross-polarizations scattering effects between the electric and magnetic fields are investigated at the oblique incidence of plane waves.

In this paper, a microstrip circuit structure for a K-Band Wilkinson power divider is presented. The designed power divider is composed of two-step taper stubs based on empirical equations. The symmetry of this circuit allows a half circuit analysis through looking at the odd- and even-model excitations. To demonstrate its performance, the proposed Wilkinson power divider has been fabricated and tested. Results show that the measured insertion loss is less than 0.3 dB and that the output reflection, input reflection and isolation are better than 16 dB, 22 dB, 16 dB, respectively, in the frequency range from 18 GHz to 27 GHz.

A key structure in so-called metamaterial mediums is the elementary split-ring resonator. We consider in this paper the low-frequency electromagnetic scattering by a split-ring particle modelled as a perfectly conducting wire ring, furnished with a narrow gap, and derive analytical solutions for the electric and magnetic dipole moments for different kinds of incidence and polarisation in the quasi-static approximation. Through a vectorial homogenisation process, the expressions discovered for the dipole moments and the related polarisability dyadics are linked with the macroscopic constitutive equations for the medium. We further show that the condition for resonance of a medium consisting of simple split-rings cannot be achieved by means of the given quasi-static terms without violating the underlying assumptions of homogenisation. Nevertheless, the results are applicable for sparse medium of rings, and we derive numerical guidelines for the applicability with some examples of the effect of the considered split-ring medium on electromagnetic wave propagation.