A conductor backed coplanar waveguide (CPW) fed multiband antenna is presented. The shorting of ground in CPW feed and conductor backed arrangement extend the area of ground plane. The proposed antenna consists of rectangular monopole with Complementary Split Ring Resonator (CSRR) engraved in the extended ground plane. The prototype antenna is designed, fabricated and measured. CSRR characteristics are also analyzed. Simulated and measured results of the antenna are in good agreement with each other and are discussed. The proposed antenna can be used for WiMAX, WLAN and RADAR applications at 3.4 GHz, 5.16 GHz and 9.5 GHz, respectively.

We propose an all circular-air-hole short-length polarization beam splitter (PBS) with high extinction ratio based on dual-core highly birefringent photonic crystal fiber (PCF). The impacts of geometrical parameters on the coupling polarization dependence, coupling length ratio (CLR), and propagation property are numerically investigated by the full-vector finite element method (FEM) and the semi-vector beam propagation method (BPM). From simulation results, it is seen that CLRs at the excitation wavelength of 1.55 μm can be optimized to be closed to the desired values of 3/2 and 4/3 to satisfy the sufficient condition of splitting polarized modes by appropriately tailoring the air-hole sizes. For the two optimal structures, the separation of x- and y-polarized modes can be achieved in short lengths of 1.41 mm and 2.89 mm at the operating wavelength of 1.55 μm, respectively. Furthermore, the extinction ratios at λ = 1.55 μm are estimated to be 97.7 dB and 88.1 dB, and the wavelength bandwidths of extinction ratio better than 15 dB are about 107 and 82 nm, respectively.

In this paper, a 3D quasistatic numerical algorithm for computation of the electric field produced by overhead power lines is presented. The real catenary form of the overhead power line phase conductors and shield wires is taken into account with an arbitrary number of straight thin-wire cylindrical segments of active and passive conductors. In order to obtain more precise results of the charge density distribution, segmentation is conducted for each overhead power line span separately. Moreover, the presence of the towers which distort the electric field and significantly reduce its magnitude is taken into account. Therefore, the towers of overhead power lines are approximated using thin-wire cylindrical segments of passive conductors with electric potential equal to zero. From self and mutual coefficients of these components, system of linear equations for computation of the charge density distribution was obtained. In the numerical example, electric field intensity distribution in the vicinity of towers and under the midspan of overhead power lines is shown. In order to verify the accuracy of the presented model, the obtained results are compared with similar published examples and results available in the literature.

The advantages of integrating beamforming Butler matrix in 4×4 Multiple-Input Multiple-Output (MIMO) systems for underground mine wireless communications in the 2.4 GHz band are investigated. To satisfy both line-of-sight (LOS) and non-line-of-sight (NLOS) conditions, two separate measurement campaigns are performed in a real L-shaped underground mine gallery; the first uses 4-elements beamforming conformal microstrip patch arrays (CMPA), while the second uses 4-elements beamforming Butler Network (BN-MIMO) by means of connecting a planar microstrip patch array to a Butler matrix. Due to its high radiation efficiency, the latter shows further performance for enhancing the channel propagation characteristics, and thus, for reducing the average path loss by about (2.2 dB, 5.1 dB) under (LOS, NLOS) conditions, respectively. Similarly, a reduction of (0.67 ns, 3.7 ns) in the RMS delay spread has been achieved to result in an additional gain of (4.6 MHz, 0.82 MHz) in the channel's coherence bandwidth. Furthermore, the orthogonal property of BN array radiation beams has led to a suppression of about (6%, 11%) in inter-subchannels correlations to boost (1.1 bit/s/Hz, 4.35 bit/s/Hz) in the channel capacity.

In this paper, we provide full-wave numerical results concerning the effective magnetic permeability of the rod-shaped ferrites which is useful in the calculation of the inductance or the efficiency of rod antennas. This study concerns the circular cross-section ferrites with a centered winding fitting the diameter of the rod. A careful attention is taken to the simulation model, and obtained results are in better agreement with the measured coils than existing solution published earlier.

A single-layer partially reflective surface (PRS) structure is presented to design single-feed Fabry-Perot resonator antennas (FPRA) with a large gain bandwidth and compact size. The design of the PRS structure applied in this antenna is based on the theory of tightly coupled antenna arrays. Owing to strong mutual coupling between the overlapped patches, the proposed antenna obtains a wider bandwidth and more compact size. Experimental results show that the antenna obtains a 32% 3-dB gain bandwidth from 8.8 GHz to 12.2 GHz, with a peak gain of 13.5 dBi. Moreover, the relative impendence bandwidth is 40.9% for the voltage standing wave ratio (VSWR) less than 2 from 8.45 GHz to 12.8 GHz.

In this paper, two-dimensional (2-D) analytical magnetic field calculations are used to compute crucial quantities of Brushless permanent-magnet (PM) machines with surface-inset PMs. The analytical magnetic field distribution is based on the subdomain technique in which the slotting and tooth-tip effects have been considered. It includes both different magnetization patterns (e.g., radial, parallel and Halbach) and different spatial distribution of winding (e.g., concentrated and distributed with one or more layers). The saturation effect of the magnetic circuit is neglected. In this investigation, the phase and line induced back electromotive force (EMF) waveforms, electromagnetic/cogging/reluctance torques, self-/mutual-inductances and unbalanced magnetic forces (UMFs) have been analytically calculated. The analytical expressions can be used for Brushless machines having surface-inset PMs with any radius-independent magnetization pattern. In this study, two slotted Brushless PM machines with surface-inset PMs have been selected to evaluate the efficacy of the analytical expressions by comparing the results with those obtained by the finite element method (FEM). One of the case studies is a 9-slots/8-poles Brushless DC (BLDC) machine with radially magnetized PMs, non overlapping all teeth wound winding and six-step rectangular armature current waveforms. The other is a 15-slots/4-poles Brushless AC (BLAC) machine with Halbach magnetization PMs, double-layer overlapping winding and sinusoidal armature current waveforms.

The general principles of design and development of microwave absorbing materials are discussed and analysed in respect to 26-37 GHz frequency range (Ka-band). Dispersive composite materials based on carbon nanotubes in epoxy resin matrix are produced, and their electromagnetic responses are investigated in Ka-band. Both theoretical and experimental results demonstrate that presented composites may be used as compact eective absorbers in 26-37 GHz range.

In this paper we develop a higher order extraction method to accelerate the convergence in the computation of broadband Green's function for an arbitrary shaped waveguide. This is applied to a homogeneous waveguide of arbitrary shape. The broadband Green's function is based on modal expansion in which the modal fields are frequency independent. The higher order extraction is obtained by using three low wavenumbers for extraction. It gives a modal expansion of Broadband Green's Function with Low Wavenumber Extraction (BBGFL) with 6th order convergence requiring much fewer evanescent modes for convergence. Numerical results are illustrated for homogeneous waveguides for both lossless and lossy dielectric cases. The accuracy of results are validated with direct method of moment (MoM) and HFSS. The BBGFL method is computationally efficient for broadband simulations.

Wideband circularly polarized antenna is required for many satellite applications. Circularly polarized (CP) Equilateral Triangular-Ring Slot (ETRS) antenna has narrow 3-dB axial ratio bandwidth (ARBW) compared to its impedance bandwidth. Two diagonal line slots were introduced to ETRS for enhancing its 3-dB ARBW. The diagonal line slots were inserted on the left and right side of ETRS. Lengths of the left and right line slots correspond to the lowest and highest frequencies of ETRS antenna 3-dB ARBW, respectively. Both diagonal line slots have successfully improved 3-dB ARBW of ETRS antenna by achieving 680 MHz or 37% fractional bandwidth. Measured results of x-z and y-z planes of radiation patterns also confirm that the antenna has bidirectional radiation and presents good CP performance within its 3-dB ARBW. ETRS antenna RHCP gain is also improved thanks to the diagonal line slots insertion.

A novel capacitive loaded U-slot defected ground structure (DGS) is presented in this letter to provide narrowband rejection property. The principles for the selective rejection and the strategies for size-reduction and external Q-factor improvement are detailed based on transmission line equivalent model and the lumped parallel RLC model developed from transmission line model at resonance frequency. The design concept is well validated by the design and measurement of an exemplary high Q BSF.

The paper presents analytical solution of nonmagnetic and conductive disc levitation problem. The alternating magnetic field exerts eddy currents in conductive disc and levitation force, subsequently. The electromagnetic field and eddy currents distributions are determined. The force acting upon nonmagnetic disc (Lorentz, Maxwell, coenergy methods) and power losses (Joule volume integral, Poynting surface integral methods) are evaluated. For example, levitation force and power losses versus field frequency are figured out. Additionally, an optimization task for power losses at constant disc volume is solved.

We develop an efficient semi-analytical technique to calculate the electromagnetic scattering from fabric structures modeled as crossed gratings of circular coated fibers of any material composition, arranged arbitrarily in yarns. The method relies on a matrix formulation based on multipole expansion for modeling conical scattering from uniaxial gratings of fibers, and employs a scattering matrix approach to obtain co- and cross-polarized transmission and reflection coefficients. The lattice sums are evaluated using an efficient adaptive algorithm based on Shank's transformation. The method can be employed for analyzing the scattering characteristics of fabric structures embedded in any arbitrary layered media. The validity of the method is verified through comparison with full-wave finite-difference time-domain simulations. A substantial performance gain is obtained, which makes the proposed method applicable to solve large-scale fabric structure.

The effects of exposure to the electromagnetic field from base stations have received considerable attention. Currently, researches have shown that the exposure level from a base station varies with time due to the traffic. The traffic for mobile communications has a temporal and spatial correlation. In this paper, we develop an approach to study the variation law of exposure to the base stations and analyze the correlation of exposure in time and in space. We use a spectrum analyzer to measure the transmission power of the base stations at the different periods of a day. We obtain the analytical expressions for representing the variation of exposure with time using Genetic Algorithm. The self correlation of exposure to a single base station in time series and the cross correlation of exposure to base stations in the same area are both discussed. We find that the self correlation coefficients of exposure to a single base station are more than 0.9 in two hours and more than 0.5 in eleven hours. Particularly, the spatial correlation of exposure is slightly stronger than the time correlation and the cross correlation coefficients are up to 0.99.

A wideband printed quadrifilar helical antenna (PQHA) using a novel single-layer compact feeding circuit is proposed in this paper. A low-cost single-layer feeding circuit which consists of a 180° compact rat race coupler and two 3 dB hybrid commercial couplers is incorporated at the bottom of the quadrifilar antenna. The antenna arms are tapered at the feeding point to improve impedance matching between the antenna and feeding circuit. The operating frequency band ranges from 1.9 to 2.3 GHz which shows that the proposed antenna is a good candidate for various applications such as satellite communication and broadcasting satellite systems. Therefore, the array of the proposed antenna on the simple cube satellite mock-up is investigated. By this antenna array configuration, a fully spherical radiation coverage is obtained around the structure. The bandwidth of the axial ratio (AR) with a wide beamwidth (160º) is 20% in operating frequency band. The measured peak gain of the proposed antenna varies between 2.6 and 3.2 dBic in the frequency band of interest. The measured 3 dB AR half-power beamwidth is 160º.

In this paper, a new analysis method of broadcast beamforming for a massive MIMO antenna array, targeting at the fifth generation mobile communication, is introduced. In order to solve the problem of narrow broadcast beam coverage, the element phase of massive MIMO antenna array is optimized using a method, which combines both numerical electromagnetic analysis method and global optimization algorithm. The analysis results show that the optimal value of 3 dB broadcast beam width for 64 elements in the horizontal plane is 36 degree, which is 0.55 times of that of the 4G base station. In addition, the optimal value of gain loss increases to about 13 dB compared with the gain of the antenna fed with equal amplitude and in phase. So it is also necessary to take the system link budget of the broadcast channel into consideration. The proposed analysis method and design solution can provide reference for the research of the next generation mobile communication.

A wireless cyber secure zone has been created by controlling RF propagation using directive antennas and noise generation to establish a functional boundary for a wireless network. Directive microstrip patch antennas were constructed in the 2.4-GHz ISM band, and a commercial router was used to generate a wireless network on a specified channel. The FM transmitters for noise generation were set to the same channel in the 2.4-GHz ISM band, and the directive microstrip patch antennas were arranged facing outward creating an inner cyber secure zone for the wireless network. Outside the cyber secure zone, the wireless network was undetectable.

A compact coplanar waveguide fed multiband antenna is proposed and investigated. The proposed antenna consists of a rectangular radiating patch and dual meander strips with a defected ground plane. The size of the fabricated prototype is 28.3 × 24 × 1.59 mm³. The proposed antenna radiates at three different resonant modes, which cover 2.29-2.63 GHz, 3.26-3.96 GHz, and 4.97-6.10 GHz. The proposed antenna can be used for TD-LTE 2300/2500 (2.305-2.4 GHz), WLAN (2.4-2.4835 GHz and 5.15-5.875 GHz) and WiMAX (2.3-2.4 GHz and 3.3-3.7 GHz) applications. The proposed antenna exhibits an omnidirectional radiation pattern in the H-plane and a dipole-like radiation pattern in the E-plane. The measured peak gains are 2.64/4.48/6.08 dBi at the 2.4/3.5/5.5 GHz operating frequency bands, respectively.

This letter presents a high gain slot antenna for K-band non-contact measurement systems. The proposed antenna consists of a slot antenna on a grooved metal structure with a single frequency selective surface. In addition to a high-gain characteristic, a reduced size is strongly required for easy embedding. These features are the main objectives of this antenna design. To achieve these two objectives, an optimization procedure, based on a global algorithm, is used. Both simulation and optimization are carried out by means a full-wave electromagnetic simulation tool. Eventually, to validate the proposed design, a prototype of the antenna has been manufactured and tested. More than 15 dB of gain is measured over the operating frequency range, while optimal gain can reach 17 dB at frequency 25.5 GHz. These characteristics make this antenna very suitable for non-contact measurement i.e. radar systems.

In this paper, a rigorous study of rectangular waveguide partially filled with longitudinally magnetized ferrite is presented. The propagation constant as a function of frequency is first obtained by the use of Transverse Operator Method. We show the existence of the complex modes in this type of structures with ferrite. In these problems, the interface between an air filled rectangular waveguide and E-plane ferrite slab loaded rectangular waveguide represent a discontinuity problem. The analysis is based on the Mode Matching Method and the Transverse Operator Method which are combined in such a way as to determine the scattering parameters. The proposed approach is validated by comparing the presented results with the published data and numerical ones obtained from commercial software.