In this paper, an ultra compact dual-band metamaterial antenna based on a new asymmetric generalized negative refractive index transmission line is introduced. The antenna is designed to support the 900 MHz GSM and 2400 RFID/WiFi bands. Moreover, the antenna size is only (15×20 mm²) which is only less than (0.08λ_g× 0.1λ_g) at the center frequency of the first resonance and (0.22λ_g× 0.29λ_g) at the center frequency of the second resonance. The theoretical design steps of the antenna are explained. The dual-band antenna design has been validated using equivalent circuit modelling, electromagnetic full wave simulations and practical measurement. The results illustrate that the antenna has the first resonance centred at 0.9 GHz and the second at 2.4 GHz with 15 dB return loss in the two bands. Good agreements among the circuit modelling, electromagnetic full wave simulation and practical measurements have been achieved.

The model for penetration of a wire braid is rigorously formulated. Integral formulas are developed from energy principles for both self and transfer immittances in terms of potentials for the fields. The detailed boundary value problem for the wire braid is also set up in a very efficient manner; the braid wires act as sources for the potentials in the form of a sequence of line multipoles with unknown coefficients that are determined by means of conditions arising from the wire surface boundary conditions. Approximations are introduced to relate the local properties of the braid wires to a simplified infinite periodic planar geometry. This is used to treat nonuniform coaxial geometries including eccentric interior coaxial arrangements and an exterior ground plane.

A compact dual-polarized antenna element integrated with balun is proposed. Two pairs of dipoles are employed for the dual-polarizations of the antenna, and strong mutual coupling between them is introduced to widen the bandwidth of the antenna. Bent dipoles are used to reduce the size of the antenna. The simulated and measured results show that the proposed antenna can cover the bandwidth ranging from 790 MHz to 960 MHz with VSWR < 1.5 and isolation > 26 dB. The antenna element is also fabricated and tested. The measured results show that the antenna can be a good candidate for the design of European Digital Dividend/CDMA800/GSM900 mobile communication base station antenna.

It has been widely verified that the hybrid finite element - boundary integral - multilevel fast multipole algorithm (FE-BI-MLFMA) is a general, efficient and accurate method for the analysis of unbounded electromagnetic problems. A variety of fast methods of FE-BI-MLFMA have been developed since 1998. In particular, the domain decomposition methods have been applied to FE-BI-MLFMA and significantly improve the efficiency of FE-BI-MLFMA in recent years. A series of fast domain decomposition methods (DDMs) of FE-BI-MLFMA have been developed. These fast DDMs can be roughly classified into two types: Schwarz DDMs and dual-primal finite element tearing and interconnecting (FETI-DP) DDMs. This paper will first give an overview of the DDMs development of FE-BI-MLFMA. Then a uniform, consistent, and efficient formulation is presented and discussed for these fast DDMs of FE-BI-MLFMA. Their computational complexities are analyzed and studied numerically.

Multispectral imaging is an important tool for understanding composite materials in many disciplines. Spectral unmixing enables the determination of individual fluorophore distributions. Due to the dispersive nature of biomaterials the observed spectra of fluorescent dyes is unknown. Spectral unmixing can be accomplished for unknown endmember spectra using minimum volume simplex analysis (MVSA). Compressive sampling (CS) is a method to reduce the computational cost of operating on sparse data sets and can be performed efficiently using NESTA based on Nesterov's algorithm. Here we demonstrate that NESTA and MVSA can be combined with a denoising threshold to create a compressive sampling and multispectral unmixing (CSMIU) method that enables efficient bioimaging and unmixing with high levels of accuracy (spectral angle distances (SADs) < 0.05). This CSMIU method may potentially enable broadband and in vivo bioimaging modalities.

Static charging of an aircraft surface can lead to electromagnetic disturbances on aircraft radio and avionic systems. This phenomenon is called Precipitation Static. Arc discharges are the main causes, and they often occur when there is a bonding defect on the surface of the aircraft. In order to find these bonding defects, often the whole aircraft has to be scanned. This paper presents a method that aims at reducing the time needed for the search of outer bonding issues. The system is composed of an instrumentation to be used in-flight, that measures the electromagnetic emissions of P-Static sources using several sensors placed on the surface of the aircraft. Then, given several signals measured from sensors and using a time domain location method based on delay estimation, it is possible to compute the source position. The method is validated on a simplified fuselage mock-up with satisfying location performance.

It is shown in this paper that the problem of reducing the number of elements for multiple-pattern arrays can be solved by a sequence of reweighted ℓ₁ optimizations under multiple linear constraints. To do so, conjugate symmetric excitations are assumed so that the upper and lower bounds for each pattern can be formulated as linear inequality constraints. In addition, we introduce an auxiliary variable for each element to define the common upper bound of both the real and imaginary parts of multiple excitations for different patterns, so that only linear inequality constraints are required. The objective function minimizes the reweighted ℓ₁-norm of these auxiliary variables for all elements. Thus, the proposed method can be efficiently implemented by the iterative linear programming. For multiple desired patterns, the proposed method can select the common elements with multiple set of optimized amplitudes and phases, consequently reducing the number of elements. The radiation characteristics for each pattern, such as the mainlobe shape, response ripple, sidelobe level and nulling region, can be accurately controlled. Several synthesis examples for linear arrays, rectangular/triangular-grid and randomly spaced planar arrays are presented to validate the effectiveness of the proposed method in the reduction of the number of elements.

We present a description of the electromagnetic field for the propagation invariant beams using scalar potentials. Fundamental dynamical quantities are obtained: energy density, Poynting vector and Maxwell stress tensor. As an example, all these quantities are explicitly calculated for the Bessel beams, which are invariant beams with circular cylindrical symmetry.

In this paper, a microstrip-fed hexagonal shape ultra-wideband (UWB) monopole antenna with triple band-notched characteristics is presented. The antenna consists of a microstrip feed line, a regular hexagonal shape radiation patch with a complementary split ring resonator (CSRR) and a pair of inverted T-shaped conductor-backed planes embedded in the antenna backside. Notched bands can be easily controlled by geometry parameters of the CSRR and conductor-backed planes. The simulated and measured results show that this monopole UWB antenna can offer an operation frequency from 2.93 GHz to 10.04 GHz with -10 dB return loss bandwidth, except three notched bands at 3.31-3.78 GHz, 5.33-5.77 GHz and 7.24-7.72 GHz for rejecting the WiMAX and downlink of X band satellite communication system signals. A good agreement between the measured and simulated results is observed. The proposed antenna provides broadband impedance matching, appropriate gain and stable radiation patterns over its operating bandwidth and can be used in wireless UWB applications.

Coupled resonators are widely used in the design of cross-coupled filters with dual-passband response and the quasi-elliptic function characteristics. In this paper, we will present a dual-band bandpass filter using only couplings between adjacent resonators, i.e. without cross-couplings. The dual-band bandpass filter with passband centre frequencies of 1747 MHz and 1880 MHz respectively is designed and fabricated using microstrip U-shaped resonators. Using coupled resonator pair as a dual-band cluster, a miniaturised structure is achieved as compared to the conventional topology. The measured responses agree closely with the simulations.

In this paper, a new printed ultra-wideband (UWB) power divider with notched band using square ring multiple-mode resonator (SRMMR) is presented. The characteristics of the proposed SRMMR are investigated by using even- and odd-mode analysis. Then, the initial UWB performance is achieved by introducing SRMMR to the basic Wilkinson power divider. Finally, a pair of parallel coupled lines is embedded into the SRMMR to achieve a desired notched band inside the UWB passband. The central frequency and the bandwidth of the notched band can be easily controlled by the electrical length and coupling coefficient of the coupled lines. To validate the design concept, a novel printed UWB power divider with notched band centered at frequencies of 5.8 GHz is designed and measured. The simulated and measured results indicate that it has a low insertion loss and good return loss performance at all the three ports, and a high isolation between the two output ports across the UWB bandwidth from 3.1 to 10.6 GHz with a small size of 0.46λg×0.69λg, where λg is the guided wavelength at 6.85 GHz.

We present in this paper an analytical model for the calculation of the electromagnetic field in a slotless surface mounted permanent magnet machines. This model takes into account the two essential directions of magnetization of the magnets, namely tangential magnetization and radial magnetization. It especially accounts for the parallel form of the magnetization direction. The model uses equivalent currents on the surfaces of the magnets, and in an original way, it uses currents in all volume of the magnet. The model is validated by numerical results obtained with a free software of calculation of the electromagnetic fields (FEMM: Finite Element Method Magnetics) which uses the finite elements method and by an existing experimental structure. The model is extended to the magnets segmented in bars and separated. It is then extended to the shape of magnets close to parallepiped forms which are really used in large machines.

This work presents a compact rectenna based on printed on paper electronics. The rectenna is printed using mass production technique on an environmental-friendly and flexible paper substrate. Only one ink layer is used. The characterized paper substrates present minimum tangent losses of 0.08. It shows at most 40 times higher tangent loss than commercial substrates (Rogers Ultralam2000). A reduction of 50% of dielectric losses can be achieved by a good selection of the paper type; the selected paper substrate is a corrugated cardboard with 0.04 loss tangent value. The designed rectenna is based on two series-mounted SMS7630 Schottky diodes. Co-design technique has been used in order to integrate different blocks for additional loss reduction. The goal of our work is the use of a recyclable cardboard substrate with low-losses compared to classical paper substrate and high losses compared to commercial substrates. The printed on cardboard rectenna presents similar performances to a rectenna etched on commercial substrates. This device aims to convert high voltage levels (1V) at low power levels (-15 dBm) for self-sustainable devices. For our application, an electrochromic display is supplied for anti-counterfeiting purposes. When a smartphone operating on Wi-Fi mode is close, the printed rectenna exhibits 970 mV DC which is sufficient to turn on the electrochromic display.

A wide bandwidth folded V-shaped patch antenna with high gain and low cross polarization is presented. The proposed antenna is composed of a folded V-shaped patch, an H-shaped coupling slot cut in the ground plane and a feed line with a stub printed on the bottom layer of the grounded substrate. By folding the V-shaped metallic patch, the proposed antenna can achieve a low profile structure and good performance in radiation patterns. The antenna element and the antenna array operating at 2 GHz were fabricated and tested. The prototypes with the single element can achieve a -10 dB return loss bandwidth of 28.5% (1.65 to 2.2 GHz) and a stable gain of 8.6 dBi, while 1×2 arrays exhibit a bandwidth of 34.1% (1.58 to 2.23 GHz) and a stable gain of 11.5 dBi.

A planar bandpass filter is proposed in this paper. Its stopband is realized by using the concept of bandstop filter. A key merit of the filter configuration is that the position of the transmission zeros can be conveniently controlled whereas the bandwidth is fixed. The bandpass filter is realized using open circuited uniform impedance resonator and stepped impedance resonators. With five reflection zeros generated in the passband, ten controllable transmission zeros are introduced to sharpen the passband skirts. Skirt selectivity can be freely controlled by tuning the impedance ratio of the stepped impedance resonators. Without coupling gaps between resonators, the structure of the filter is simple and easy to fabricate. To illustrate the concept, a bandpass filter with ten transmission zeros is designed, fabricated and measured. Simulated and measured results are found to be in good agreement with each other, with insertion loss in the passbands less than 1 dB.

An anisotropic dielectric resonator antenna (ADRA) with uniaxial and biaxial permittivity tensors is characterized by using the dielectric waveguide model. An approximate formula for the Q factor of ADRA is derived. Then, it is shown that by certain conditions a wideband ADRA can be designed. Samples of simulation results are shown to demonstrate the capabilities of the proposed anisotropic technique for enhancing the bandwidth of ADRA. The proposed antenna is simulated by two full wave packages, Ansoft HFSS and CST Microwave Studio, and a good agreement is observed among the results.

Tracking multiple maneuvering targets for automotive radar is a vital issue. To this end, a novel DS-UKGMPHD algorithm which combines diagraph switching (DS), unscented Kalman (UK) filter and Gaussian mixture probability hypothesis density (GMPHD) filter is proposed in this paper. The algorithm is capable of tracking a varying number of target cars detected by automotive radar with nonlinear measurement models in a cluttered environment. In addition, variable structure is used to accommodate various target motions in real world. Simulation results demonstrate the superiority of the presented algorithm to IMM-UKGMPHD filter in terms of estimation accuracy of both number and states.

Investigation of a unit cell in terms of reflected wave amplitude and phase, for designing linearly polarized single layer Textile-Reflectarray (TRA) at C-band, is presented. The relative dielectric constant of the material is extracted using resonance method, and a WLAN antenna is designed to verify the accuracy of extracted material parameter. An error of 5% is observed in the extracted dielectric constant, when performance of WLAN antenna is measured at WI-FI Band (2.4 GHz). The extracted dielectric constant is used in the unit cell designing for TRA at the C-Band (5.8 GHz). The radiating element is made using laying technique with conductive thread. A square patch with a ring is selected after analyzing multiple geometries of the patch providing the required reflected phase range and low losses. By varying size of patch and ring of single layer unit cell in CST periodic environment, reflected phase range of 360 degree is achieved, which is required for RA designing. The solid copper ground plane at the bottom of unit cell is replaced with conductive shielded fabric with high level signal attenuation. Four different sizes of textile unit cells are fabricated using conductive thread, and the reflected phase and amplitude are measured using waveguide method. The simulated and measured results are compared when solid copper ground plane at the bottom of unit cell has been replaced with shielded fabric. The proposed method provides the first step towards designing flexible high gain textile reflectarrays.

Filtered backpropagation (FBPP) is a well-known technique used in Diffraction Tomography (DT). For accurate reconstruction of a complex-valued image using FBPP, full 360˚ angular coverage is necessary. However, it has been shown that by exploiting inherent redundancies in the projection data, accurate reconstruction is possible with 270˚ coverage. This is called the minimal-scan angle range. This is done by applying weighting functions (or filters) on projection data of the object to eliminate the redundancies. There could be many general weight functions. These are all equivalent at 270˚ coverage but would perform differently at lower angular coverages and in presence of noise. This paper presents a generalized mathematical framework to generate weight functions for exploiting data redundancy. Further, a comparative analysis of different filters when angular coverage is lower than minimal-scan angle of 270˚ is presented. Simulation studies have been done to find optimum weight filters for sub-minimal angular coverage. The optimum weights generate images comparable to a full 360˚ coverage FBPP reconstruction. Performance of the filters in the presence of noise is also analyzed. These fast and deterministic algorithms are capable of correctly reconstructing complex valued images even at angular coverage of 200˚ while still under the FBPP regime.

Frequency diverse array (FDA) uses a small frequency increment at each antenna element to get a range, angle and time dependent beam pattern. Although linear frequency offset is used in most radar systems, nonlinear frequency offset is also very useful for analyzing FDA radar. A logarithmic frequency offsets based FDA (log-FDA) removes the inherent periodicity of FDA beam pattern to get a single maxima in area of interest. Multiple input multiple output frequency diverse array (MIMO-FDA) radar is also presented recently to provide some improvements compared to FDA radar. In this paper, a new hybrid scheme is proposed in which each subarray of MIMO-FDA uses a variable logarithmic offset. The resultant system, called MIMO-log-FDA, uses not only a different logarithmic offset, but also unique waveform in each subarray. Different logarithmic offsets contributed in terms of getting more control on width of beampattern, while the different waveforms provide diversity, which can be exploited at the receiver of the proposed system. Some improvements in transmit beam patterns have been shown for MIMO-log-FDA, followed by detailed signal model for better estimation of target at the receiving side. Performance analysis is also done in terms of signal to interference plus noise ratio (SINR) and Cramer-Rao lower bound (CRLB). Simulation and results verify the effectiveness of proposed scheme by comparing it with Log-FDA and MIMO-FDA radar.