This paper describes a high-gain CMOS low-noise amplifier (LNA) for 2.4/5.2-GHz WLAN applications. The cascode LNA uses an inductor at the common-gate transistor to increase its transconductance equivalently, and therefore it enhances the gain effectively with no additional power consumption. The LNA is matched concurrently at the two frequency bands, and the input/output matching networks are designed with two notch frequencies to shape the frequency response. The dual-band LNA with the common-gate inductor is designed, implemented, and verified in a standard 0.18-μm CMOS process. The fabricated LNA which consumes 7.2 mW features gains of 14.2 dB and 14.6 dB, and noise figures of 4.4 dB and 3.7 dB at the 2.4-GHz and 5.2-GHz frequency bands, respectively. The proposed LNA demonstrates a 4.9-7.8 dB gain enhancement compared to conventional cascode LNAs, and the chip size is 1.06 mm × 0.79 mm including all testing pads.

In this paper, we propose a novel H-infinity filter based particle filter (H∞PF), which incorporates the H-infinity filter (H∞F) algorithm into the particle filter (PF). The basic idea of the H∞PF is that new particles are sampled by the H∞F algorithm. Since the H∞F algorithm can fully take into account the current measurements, when the new algorithm calculates the proposed probability density distribution, the sampling particles can take advantage of the system current measurements to predict the system state. The particles distribution we obtained approaches nearer to the state posterior probability distribution and the H∞PF alleviates the sample degeneracy problem which is common in the PF, especially when the maneuvers of the target tracking are large. Furthermore, the H∞F algorithm can adjust gain imbalance factor by adjusting disturbance decay factor, from that the new algorithm can get the compromise between the accuracy and robustness and we can obtain satisfied accuracy and robustness. Some simulations and experimental results show that the proposed particle filter performed better than the PF and the Kalman particle filter (KPF) in tracking maneuvering target.

In this paper, we propose a 3D model to characterize the field scattered by an urban area, which is composed of a group of buildings, for both monostatic and bistatic radar configurations. This model is based on a ray-tracing technique combined with the Uniform Theory of Diffraction (UTD). It is useful not only in elucidating mechanisms of ray propagation through the observed area, but also in evaluating the amplitude and the phase of any point in the far-zone scattered field above the ground. In order to validate the model, some comparisons with the commercial software XGTD R are presented. In addition, our model is tested against 33-37 GHz indoor measurements conducted in the anechoic chamber of the "ElectroMagnetic Effects Research Lab" (EMERL) in Singapore. These latter comparisons have shown that the model can predict precisely the location of a target placed between two metallic plates representing walls.

A semi-circle monopole printed antenna is proposed. Its radiation unit and the ground plane are in the same shape, and both of them are coplanar-printed. The antenna is fed by a microstrip line, which is connected to the radiation unit through a via-hole. The measured impedance bandwidth is about 3.1GHz-15.1GHz with VSWR<2, and the ratio bandwidth can reach 4.9:1. The omnidirectional characteristic is also excellent in H-plane. Moreover, because of the introduction of the semi-circle radiation unit and the ground plane, the length of the radiation unit can be miniaturized in polarization direction, which is only 14% of wavelength of the lowest operating frequency. The antenna size is just 29 mm×29.5 mm×1.0 mm, which can make it well integrate into UWB communication systems.

A compact paw-shaped multiband monopole antenna for Wireless local area network(WLAN) and worldwide interoperability for microwave access(WiMAX) applications is presented. The proposed antenna is composed of a paw-shaped monopole element and a rectangular ground plane with simple configuration. This antenna can easily be fed by using a 50ohm probe feed with SMA connector. By adjusting a few parameters of the three arms, the resonant frequencies can be easily tuned. The proposed antenna was analyzed and optimized to cover three bandwidths from 2.32 to 2.84, 3.39 to 4.34 and 5.11 to 5.91GHz that for WLAN and WiMAX applications respectively, with the return loss of better than 10 dB. The performances of the antenna are demonstrated along with measured and simulated results. Moreover, simulated and experimental results with different parameters of the antenna are given.

Chipless ultra-wideband (UWB) has been proposed as a low-cost alternative for radiofrequency identification (RFID). In this paper, a comprehensible theoretical introduction to time-domain operation of a UWB RFID tag is described, and a circuit model is proposed. For commercial applications low-cost RFID readers are demanded. To this end, this paper addresses the measurement of time-coded UWB chipless tags for RFID in time domain. Two different setups to detect time-coded tags are presented, one based on a commercial UWB impulse radar (IR) and the other based on a vector network analyzer (VNA). The experimental results show the feasibility of using an IRUWB radar as a UWB RFID reader, achieving very good read ranges.

Coaxial magnetic gear (CMG) is a non-contact device for torque transmission and speed variation which exhibits promising potential in several industrial applications, such as electric vehicles, wind power generation and vessel propulsion. CMG works lying on the modulating-effect aroused by the ferromagnetic segments. This paper investigates the optimum design for improving the modulating-effect. Firstly, the operating principle and the modulating-effect is analyzed by using 1-D field model, which demonstrates that the modulatingeffect is essential for the torque transmission capacity of CMGs, and the shape of the ferromagnetic segments have impact on the modulatingeffect. Secondly, the fitted model of the relationship between the maximum pull-out torque and the shape factors including radial height, outer-edge width-angle and inner-edge width-angle is built up by using surface response methodology. Moreover, FEM is engaged to evaluate its accuracy. Thirdly, the optimum shape of the ferromagnetic segment is obtained by using genetical algorithm.

A circular wide-slot UWB antenna with dual band-notched characteristics is proposed in this paper. The microstrip-fed antenna mainly consists of a calabash-shaped feeding patch and a metal ground with a circular slot etched. Dual notched bands are realized by introducing arc-shaped parasitic strip and slot on the ground plane. The measured results show that the proposed antenna can operate at the range of 2.91-11.45 GHz with VSWR < 2 for UWB applications, except the notched bands of 3.38-3.71 GHz and 5.39-6.27 GHz for the 3.5 GHz WiMAX and 5.8 GHz WLAN, respectively.

We experimentally investigate the properties of nonlinear pulses in coupled transmission lines with regularly spaced Schottky varactors. The c and π modes are different propagation modes that can be developed on a coupled line. Time-domain measurements show that both modes support soliton-like pulses due to the presence of the Schottky varactors; small c-mode pulses are generated by colliding two π-mode pulses traveling in opposite directions. Moreover, we discuss the relationship of the amplitude of the newly generated c-mode pulses with different bias voltages and π-mode-pulse amplitudes.

The paper discusses the radiation of compressed high power short RF pulses using two different types of antennas: (i) A simple monopole antenna and (ii) a novel array design, where each of the elements is constructed by combining a compressor and a radiator. The studies on the monopole antenna demonstrate the possibility of a high power short RF pulse's efficient radiation even using simple antennas. The studies on the novel array design demonstrate that a reduced size array with lower pulse distortion and power decay can be constructed by assembling the array from elements each of which integrates a compressor and a radiator. This design idea can be used with any type of antenna array; in this work it is applied to a phased array.

Proper design of efficient microwave energy compressors requires precise understanding of the physics pertinent to energy accumulation and exhaust processes in resonant waveguide cavities. In this paper, practically for the first time these highly non-monotonic transient processes are studied in detail using a rigorous time-domain approach. Additionally, influence of the geometrical design and excitation parameters on the compressor's performance is quantified in detail.

This paper presents both simulation and experimental study to detect and locate breast tumors along with their classification as malignant and/or benign in three dimensional (3D) breast model. The contrast between the dielectric properties of these two tumor types is the main key. These dielectric properties are mainly controlled by the water and blood content of tumors. For simulation, electromagnetic simulator software is used. The experiment is conducted using commercial Ultrawide-Band (UWB) transceivers, Neural Network (NN) based Pattern Recognition (PR) software for imaging and homogenous breast phantom. The 3D homogeneous breast phantom and tumors are fabricated using pure petroleum jelly and a mixture of wheat flour and water respectively. The simulation and experimental setups are performed by transmitting the UWB signals from one side of the breast model and receiving from opposite side diagonally. Using discrete cosine transform (DCT) of received signals, we have trained and tested the developed experimental Neural Network model. In 3D breast model, the achieved detection accuracy of tumor existence is around 100%, while the locating accuracy in terms of (x,y,z) position of a tumor within the breast reached approximately 89.2% and 86.6% in simulation and experimental works respectively. For classification, the permittivity and conductivity detection accuracy are 98.0% and 99.1% in simulation, and 98.6% and 99.5% in experimental works respectively. Tumor detection and type specification 3D may lead to successful clinical implementation followed by saving of precious human lives in the near future.

An efficient hybrid method, based on time-domain integral equation (TDIE) and time-domain physical optics (TDPO), is proposed for studying on transient electromagnetic responses of some wire and surface structures illuminated by an electromagnetic pulse (EMP), respectively. Two groups of triangular-type basis functions are used to expand the currents on both of them. The derived hybrid TDIE-TDPO equations are solved by marching-on-in-time (MOT) scheme. In comparison with the full TDIE-based MOT method, computational complexity of our developed method is reduced significantly, and at the same time, with high accuracy maintained. Numerical results of EMP responses of some typical wire and surface structures are presented to demonstrate its versatility, accuracy and efficiency, with proximity effects between them captured and discussed.

Antenna characterization in presence of obstacles requires removing multipath effects in order to retrieve the nondistorted antenna radiation pattern. In this contribution a new approach based on the Sources Reconstruction Method is proposed. The idea is to characterize the Antenna-Under-Test (AUT) and the region where the scatterers are located through a set of equivalent currents. Finally, the reconstructed equivalent currents on the contour enclosing the AUT can be used to recover the AUT radiation pattern, removing most of the distortion effect due to the presence of the scatterers.

In complex electromagnetic (EM) environment, EM field distribution inside a metallic enclosure is determined by the external EM radiation and emissions from internal contents. In the design of an electronic system, we usually need to estimate the EM field level in a concerned region inside the enclosure under various EM environments. In this paper, we use artificial neural network (ANN), rather than full wave analysis, combined with the numbered measurements to predict the EM field in the concerned region inside a metallic enclosure. To verify this method, a rectangular metallic enclosure with a printed circuit board (PCB) is illuminated by external incident wave. The measured electric fields inside the enclosure combined with ANN model based on back propagation (BP) training algorithm are used to estimate the values of electric field. The calculation is fast and predictions reveal good agreement with the measurements that validate this method.

Two directional UWB monopole antennas are proposed. It is shown that a design methodology for omnidirectional UWB rectangular planar monopole antennas can be applied for directional ones. The directional features are taken by introducing a slanting angle between the radiator and the ground plane. The slanting angle also plays a role in the low cutoff frequency, and it is considered in a proposed equation to determine that frequency. For the two UWB antennas the radiators have a rectangular shape, and the bandwidth is extended by choosing beveling angle and an appropriate height-width ratio. The developed antennas have a bandwidth wider than 10 GHz for a reflection coefficient lower than -10 dB. The directional radiation pattern has an average gain of 5 dB.

An effective series RLC model for the electromagnetic response of weakly absorbing dielectric sphere near the first magnetic dipole resonance was developed, and the effective magnetic properties of Mie resonance-based dielectric metamaterials were obtained in terms of this model. In comparison with traditional effective medium theory such as extended Maxwell-Garnett (EMG) theory based on Mie model, this approach is more intuitive and can give an analytical dependence of the magnetic properties of the composite on the electromagnetic and geometric parameters of the constituting dielectric particles.

A novel miniaturized microstrip six-port junction is presented. The new structure effectively reduces the occupied area to 25% of the conventional six-port junction due to two open loaded stubs. The design is validated both by using momentum of Advanced Design System and by measurement.

This paper presents a novel contribution for the analysis of skin effect phenomena in inhomogeneous tubular conductors. For homogeneous tubular geometries the skin effect diffusion equation has an analytical solution described by a combination of Bessel functions, but, when the conductivity and magnetic permeability of the tubular conductor arbitrarily depend on the radial coordinate an analytical solution cannot be found. However, this work shows that closed form solutions for the electromagnetic field and conductor internal impedance do exist, provided that a specific type of radial variation of medium parameters is considered --- tubular structures like these are coined here Euler-Cauchy Structures (ECS). Analytic and computation results concerning general and particular ECS are presented, validated, and discussed. Besides its intrinsic theoretical importance, the simple closed form solutions that we have found can be of interest as benchmark tools for testing the accuracy and performance of EM field software solvers.

When developing a wireless communication system, a designer should consider the associated radiated power density, electromagnetic compatibility (EMC), and specific absorption rate (SAR). In this paper, high-impedance surfaces (HISs) are designed as an EM protection screen to reduce the interaction between an antenna and the user behind the screen. The effects of an HIS screen with a finite number of cells placed near a monopole antenna for the application of the 2.4 GHz WLAN band were thoroughly investigated. The screen is first-ever proposed not only to reduce the backward radiation from the antenna, but also to shift the impedance-matching band of the antenna and to adjust the corresponding bandwidth. As a result, the SAR behind the screen is noticeably lowered, and the out-of-band spurious emission from the antenna can be reduced. Two typical kinds of HIS structures, mushroom-shaped and Jerusalem Cross HISs (abbreviated as MSHIS and JCHIS, respectively), were investigated by numerical simulations and measurements. Three different measurement techniques were proposed for predicting the operating frequency band of an HIS. Some HIS-added antenna prototypes were constructed and studied. It was found that the MSHIS and JCHIS can adjust the impedance-matching band of the antenna, do not affect the radiation performance in the forward direction, and can significantly reduce the backward radiated power. In addition, the measured maximum SAR has been significantly reduced from 0.976 W/kg for the monopole antenna without an HIS to 0.037 and 0.038 W/kg, respectively, for the antenna with an MSHIS and a JCHIS.