This paper extends the existing transmission and capacity analysis in order to investigate the broadband potential of overhead high-voltage/broadband over power lines (HV/BPL) connections where a single repeater is additively deployed between their existing transmitting and receiving ends (overhead HV/BPL connections with two-hop repeater system). The contribution of this paper is three-fold. First, the broadband performance of various overhead HV/BPL connections with two-hop repeater system has been studied with regard to their cumulative capacity. The analysis and relevant simulations validate the potentially excellent communications medium of overhead HV/BPL channels over a 25 km repeater span well beyond 100 MHz in terms of cumulative capacity. In addition, through the deployment of two-hop repeater systems, apart from the upsurge of cumulative capacity, overhead HV/BPL connections become more adaptive to different capacity requirements. Second, it is found that overhead HV/BPL network capacity performance depends drastically on factors such as the overhead HV grid topology and the noise characteristics. Through the deployment of two-hop repeater systems, capacity losses due to existing aggravated overhead HV/BPL topologies and high noise environments are significantly reduced. Third, the numerical results reveal the importance of considering as suitable mitigation technique the deployment of overhead HV/BPL connections with two-hop repeater system. Except for the low-cost and quick technology upgrade of existing overhead HV/BPL networks, this mitigation technique may permit the future broadband exploitation of overhead HV/BPL networks and their interoperability with other broadband technologies.

A novel Koch fractal printed Yagi-Uda antenna fed by coplanar waveguide (CPW) is proposed and analyzed. The antenna has first-order Koch fractal monopoles, and the monopoles' ground plane acts as the ground plane of the antenna. The radiation characteristics of the antenna are simulated by CST Microwave Studio^® and explained by the simulated results. The antenna's currents distribution becomes more uniform after being fractal, which is conducive to increasing antenna's radiation directivity. The proposed Koch fractal Yagi-Uda antenna has an operating band of 885-913 MHz (relative bandwidth 3.1%) with the center frequency of 900 MHz. The total antenna size is 171 mm×85 mm (0.51λ×0.25λ) and the length in the antenna's polarization direction is only 25% of the wavelength corresponding to the center frequency. Compared to traditional Yagi-Uda antenna, the proposed antenna can achieve a 50% miniaturization effect.

This paper addresses the problem of designing statistical features for the extraction of building-up areas (BAs) from highresolution polarimetric synthetic aperture radar (PolSAR) imagery. The idea is to represent a building-up area by the distribution of its mid-level components, called intermediates, which are statistical patterns unsupervisedly learnt from PolSAR images. More precisely, by analyzing the structural properties and the polarimetric characteristics exhibited in various terrain types, we propose two kinds of midlevel features for small regions: the cluster based statistical feature (CSF) and the scattering mechanism based statistical feature (SMSF). In detail, for the CSF, the intermediates are the K-mean clusters with Wishart distance of the PolSAR images; for the SMSF, the intermediates are the scattering mechanism categories obtained by relying on a four-component decomposition with deorientation of the PolSAR images. In contrast with existing features for describing BAs, the proposed features, i.e., CSF and SMSF, capture more complex context information of BAs. We compare the proposed features with those based on the Gaussian Markov random field (GMRF) models, which have been proven to be suitable for BAs mapping. Experimental results on RADARSAT-2 datasets demonstrate the effectiveness of the proposed features.

A new high isolation lumped-element 180º hybrid, using electronically adjustable filters with varactor diodes, are proposed. This design is very simple and is based on only two configurable low order (N = 2) filters. Due to the limited tuning frequency range of varactor diodes, maximum near-octave frequency coverage of 2.5-5 GHz was planned in the high isolation hybrid. An impressive simulated typical isolation in the range of >60dB was achieved. One of the typical applications of developed hybrids could be the conversion of 70MHz IF to microwave frequencies, with broadband mixers in single-conversion converters, and with very high LO rejection (>60 dB).

A novel design concept of a compact printable orientation independent chipless RFID tag is presented. The tag consists of a circular patch loaded with multiple slot ring resonators. This symmetric frequency domain based tag has the advantage to be read from any orientation with the reader antennas. The tag can be read in close proximity by chipless RFID tag reader with waveguide(s) and also can be read in both near field and far-field of the RFID tag reader with antennas. This tag does not have a ground plane and has higher data density compared to the existing printable chipless tags. The usability of this single sided tag in close proximity is verified by waveguide measurements for both proximity applications such as on ID access cards, item level tagging etc. and slot reading application such as on banknotes, credit cards etc.

The paper deals with the modelling, practical implementation and characterization of a directional antenna controllable through 360° in the [2-2.5 GHz] frequency band. The antenna is composed of a central omnidirectional broadband monopole feed surrounded by a metamaterial made of one or two controllable layers of metallic strips printed on a dielectric substrate, which can be electrically continuous or discontinuous. Following the electrical state of these strips, the metamaterial can be reflective or transparent. Then by controlling the distribution of reflective and transparent regions of the latter metamaterial around the central feed, a directional emission having an angular beamwidth lower or equal to 60° and controllable through 360° is produced in the UMTS and WIFI frequency bands, demonstrating the wideband operation of this antenna.

In this paper, a finite-difference based method is presented to simulate the electromagnetic field generated by arbitrarily-oriented coil antennas in three-dimensional (3-D) complex underground media. The media have multiple layers in both the vertical and horizontal direction and can be fully anisotropic. The developed finite-difference method uses a staggered grid to approximate a vector equation in terms of the scattered electric field. The resultant linear sparse matrix is solved iteratively using a generalized minimal residual (GMRES) algorithm and an incomplete LU precondition technique is applied to improve the convergence behavior of the linear equation, thus accelerate the solution. The developed algorithm is validated by numerical examples and then applied to the simulation and study of the popular triaxial induction tools in electrical well logging engineering for anisotropy detection.

A novel fourth-order half-mode substrate integrated waveguide (HMSIW) filter with dual-mode microstrip resonator is presented. The dual-mode resonator is etched on the top metal layer of HMSIW cavity, so the size can be reduced greatly. The filter has compact size and wide stopband in comparison with conventional SIW filters. Microstrip resonators and cavity resonators are integrated in one filter to achieve the goal of smaller size and better performance. Two filter samples are designed and fabricated, with good agreement between the measured and the simulated S-parameters.

The ground plane of wireless handheld devices plays a significant role in the electromagnetic behavior determining bandwidth, efficiency, and radiation patterns. Therefore, it is necessary to determine the frequency region where the ground plane can be better excited, especially for low frequencies where the performance of the radiating system is critical due to size limitations with respect to the operating wavelength. A fast method based on the radar cross section (RCS) is presented for computing the frequency at which the ground plane can be excited. The proposal is applied to three typical wireless platforms: a handset phone, a smartphone, and a clamshell phone. The method is compared with characteristic mode analysis and the results demonstrate a very good agreement in the resonant frequency prediction. Complex platforms using metallic strips and slots in the ground plane are analyzed using RCS which gives physical insight into the electromagnetic performance.

In this work, a sub-millimeter wave frequency scanning 8 x 1 element antenna array is presented for its use in a terahertz imaging system operating in the 220-330 GHz frequency band. The antenna array is formed by eight open ended waveguides, a phase-shifting network implemented with WR-3 rectangular waveguides and a power divider. Dielectric rods are used to improve the radiation patterns at large beam-steering angles. Prototypes of antenna arrays with and without the dielectric rods have been manufactured and experimentally characterized. A beam-steering range greater than 40° has been obtained for a frequency sweep between 270 GHz and 330 GHz.

This paper proposes a novel nano-sinusoid particle to be employed in enhanced localized surface plasmon resonance (LSPR) bio-sensing devices. Numerical investigations are carried out to demonstrate advantages offered by the proposed nano-particle on LSPR enhancement over other nano-particles including noble nano-triangles and nano-diamonds. Although nano-triangles exhibit high concentration of the electric field near their tips, when illuminated with a light polarized along the tip axis, they present only one hot spot at the vertex along the polarization direction. To create a structure with two hot spots, which is desired in bio-sensing applications, two nano-triangles can be put back-to-back. Therefore, a nano-diamond particle is obtained which exhibits two hot spots and presents higher enhancements than nano-triangles for the same resonant wavelength. The main drawback of the nano-diamonds is the fluctuation in their physical size-plasmon spectrum relationships, due to a high level of singularity as the result for their four sharp tip points. The proposed nano-sinusoid overcomes this disadvantage while maintaining the benefits of having two hot spots and high enhancements.

We study the propagation of waves on infinite and finite size arrays made of subwavelength magnetoelectric resonators. We propose an analytical study where each magnetoelectric resonator is modelled simultaneously by an electric and a magnetic dipole. We show how near field coupling and wavenumber quantification due to the finite size of the structure induce a frequency splitting of the resonator fundamental mode. We theoretically demonstrate that despite a spatial period of the waves smaller than half wavelength (in vacuum), the structure can efficiently emits radiations. An analytic expression of the Q factor associated to the radiation losses is proposed. To correctly estimate this factor, we show that not only near but also far field interaction terms between the dipoles must to be considered.

In this work, a new method has been proposed for the finite-difference time-domain (FDTD) analysis of the transient grounding resistance (TGR) of large grounding systems. To calculate the TGR, a coarse grid has been occupied to model the earthing conductor, the CPML is chose to truncate the computational domain, and parallel implementation is involved to overcome the memory limit of the serial FDTD. With this model, the effect of the earthing conductor number and topology structure, the buried depth, and the ground permittivity and conductivity on the TGR is tested to find an optimized program to decrease the TGR of the lightning protection grounding systems.

Standard radar detection process requires that the sensor output is compared to a predetermined threshold. The threshold is selected based on a-priori knowledge available and/or certain assumptions. However, any knowledge and/or assumptions become inadequate due to the presence of multiple targets with varying signal return and usually non stationary background. Thus, any fixed predefined threshold may result in either increased false alarm rate or increased track loss. Even approaches where the threshold is adaptively varied will not perform well in situations when the signal return from the target of interest is too low compared to the average level of the background. Track-before-detect (TBD) techniques eliminate the need for a detection threshold and provide detecting and tracking targets with lower signal-to-noise ratios than standard methods. However, although TBD techniques eliminate the need for detection threshold at sensor's signal processing stage, they often use tuning thresholds at the output of the filtering stage. This paper presents a Hidden Markov Model (HMM) based target detection method that avoids any thresholding at any stage of the detection process. Moreover, since the proposed HMM method is based on the target motion models, the output of the detection process can easily be employed for manoeuvring target tracking.

Iris type waveguide to cavity couplers are used to couple power to particle accelerator cavities. Waveguide to cavity coupling for arbitrarily oriented rectangular iris is analyzed using Bethe's small hole coupling theory. Magnetic moment of rotated iris is obtained by defining its dyadic magnetic polarizability. Power radiated by magnetic moment into the incoming waveguide is used for coupling calculations at arbitrary angle. A close agreement is found between the proposed theory, simulations and microwave measurements.

The aim of this study is to address the management of urinary problems by detecting changes in the volume of urine within the human bladder using low cost, low power, wearable Ultra Wideband (UWB) sensors and signal processing techniques. The paper describes experiments on the classication of six three-layer dielectrically representative bladder phantoms, mimicking a range of muscle and bladder wall-to-wall distances. The process involves the illumination of the bladder with a UWB pulse. Due to the dielectric contrast between urine and bladder wall tissue at microwave frequencies, an electromagnetic reection is generated at both the anterior and posterior bladder wall. These reflections are recorded, the salient features are extracted and processed by a classification algorithm to estimate the volume of urine present in the bladder. To evaluate the prototype system, a number of physical bladder phantoms were constructed, each mimicking bladders of different volumes. Principal Component Analysis (PCA) was applied and the processed features were classified by a k-nearest neighbour learning algorithm to estimate the state of the bladder (small, medium or full). The paper describes the bladder phantom prototype systems and the experimental setup. Results illustrate detection of phantom bladder states with an accuracy of up to 91%.

This paper proposes a rectifying antenna (rectenna) for operation in the ISM (Industrial, Scientific and Medical) band centered at 2.45 GHz. It consists of a modified circular monopole loaded with a rectangular ring and a half-wave rectifier. Numerical and experimental data are reported and discussed. From measurements, it is demonstrated that, when the power density incident on the monopole is 155 μW/cm², the device here presented exhibits values of the RF-to-DC conversion efficiency higher than 30 % in the frequency range 2.35-2.5 GHz with a maximum of about 50 % at 2.45 GHz.

Rigorous mathematical Method of Moments (MoMs) for analyzing various radiating spherical structures is presented in this paper by using Dyadic Green's Functions (DGFs) in conjunction with Mixed Potential Integral Equation (MPIE) formulation. With the aid of linear Rao-Wilton-Glisson (RWG) triangular basis functions and by converting spherical DGFs to Cartesian DGFs, a conformal dipole antenna in free space and over a Perfect Electric Conductor (PEC) sphere is analyzed. The characteristics of such antennas are computed by applying multilayer spherical DGFs and asymptotic approximation methods. Mutual couplings between elements of a conformal dipole antenna array in free space and over a conducting sphere are also investigated. Good agreement between the computational results obtained by the proposed methods and those obtained from commercial simulator packages shows accuracy and high convergence speed of the presented methods.

We numerically studied the spectrum of Cherenkov optical radiation by a nonrelativistic anisotropic electron bunch crossing 3D dispersive metamaterial. A practically important case when such a medium is described by Drude model is investigated in details. In our theory only parameters of a metamaterial are fixed. The frequency spectrum of internal excitations is left to be defined as a result of the numerical simulation. It is found that a periodic field structure coupled to plasmonic excitations is arisen when the dispersive refractive index of a metamaterial becomes negative. In this case the reversed Cherenkov radiation is observed.

A scalar Frequency-Domain Finite-Difference approach to the mode computation of elliptic waveguides is presented. The use of an elliptic cylindrical grid allows us to take exactly into account the curved boundary of the structure and a single mesh has been used both for TE and TM modes. As a consequence, a high accuracy is obtained with a reduced computational burden, since the resulting matrix is highly sparse.