A new reciprocal heuristic diffraction coefficient for lossy dielectric wedge is presented which is applicable to arbitrary positions of transmitter and receiver in a complex channel environment. The prediction obtained using proposed coefficient is compared with those obtained using rigorous Maliuzhinets'solution. The comparison shows significant improvement over available heuristic coefficients. The coefficient is valid for both parallel and perpendicular polarizations. Further, the measurement of the electric field in the vicinity of edge of the building is carried out, and the measurement result, thus obtained, is compared with predictions using the proposed coefficient.

In this paper, a novel band-notched circular slot (BNCS) antenna for ultra-wideband (UWB) communication is proposed. This antenna is comprised of a circular stub that excite similar-shaped slot aperture. The proposed antenna is designed on the RO4350B substrate with thickness of 500 μm and relative permittivity (ε_r) of 3.4 to operate in UWB band released by the US's Federal Communications Commission (FCC) in 2002 (i.e., 3.1-10.6 GHz). To reject the frequency band of 5.15-5.825 GHz, which is limited by IEEE 802.11a and HIPERLAN/2, an inverted-cup strip is parasitically attached to the feed layer. The size of our proposed antenna is 50×50 mm², and this antenna has good radiation characteristics. Effects of varying the parameters of parasitic inverted-cup strip on performance of the proposed antenna have been studied. The antenna with optimal parameters obtained from parametric study is fabricated and measured. It is observed that the simulated and experimental results have good agreement with each other.

Relationships between the properties of surface waves in radar absorbing materials (RAM) layers and mono-static radar cross section reduction (RCSR) performances of a coated slab are studied. In this paper, two kinds of RAM were employed for double-layer coating. By changing the thickness of each layer and the order of RAMs, mono-static RCSR performances of the coated slab are studied. Simultaneously mono-static RCSR performances of a slab coated with equivalent medium of the considered RAMs in situ are calculated and compared with the previous ones in regard to the properties of surface waves. It is found that surface waves in between layers for various coated projects can be evaluated. Our results suggest that the optimal coated order for RAMs exists, and the method may be efficient for coating strategy with various kinds of RAMs. Electromagnetic scatterings of the equivalent medium exclude the effect of surface waves in between layers. Therefore, the equivalent medium theory is not appropriated for the research of electromagnetic scattering on lossy mediums.

A Dual band Microstrip Antenna Arrays (DbMSAA) incorporated with Mushroom Electromagnetic band Gap (MEBG) and modified Minkowski Electromagnetic Band Gap structures to further improve its radiation characteristics is reported in this work. The two different types of EBG structures work like a Band Rejecter (BR), separating the branch of feed line feeding two different groups of patch antenna arrays operating at 2.4 GHz and 5.8 GHz, thus making them operate individually at their particular frequencies, simultaneously. Initially, the possibilities of having a uniform and controlled radiation patterns are quite complicated to achieve due to the single port feeding technique used and developments of grating lobes at the higher band frequency, but, through the incorporation of the EBG structures, the problems could be solved immediately. The antenna's performance is improved where the grating lobes at 5.8 GHz are diminished, and the radiation patterns of the dual band antenna at both frequencies become more symmetrical with increased gain.

A novel compact resonator for LPF is proposed in this paper. It is composed of a circular hairpin resonator and a pair of coupled parallel stepped impedance resonators (SIRs) inside. With the loaded SIRs, additional two transmission zeros can be introduced and adjusted easily to cancel the spurious responses for stopband extending, while do not change the filter size. Filters using one and two of the new cells were designed and measured. The two-cell LPF has an insertion loss less than 0.6 dB from DC to 1.6 GHz, including attenuation of double SMA transitions at both sides of the circuit which is about 0.3 dB, and a wide -10 dB stopband from 2.5 to 13 GHz (corresponding to 146% normalized 10 dB stopband), but has a size of only 0.129 λg × 0.073 λg.

Comparing with an all-dielectric binary photonic crystal, we show, in this work, that the photonic band gap in ternary metal-dielectric photonic crystal can be significantly enlarged. First, the band gap enlargement due to the addition of the metallic film is examined in the case of normal incidence. Next, in the oblique incidence, a wider omnidirectional band gap can be obtained in such a ternary metal-dielectric photonic crystal. All the theoretical analyses are made based on the transfer matrix method together with the Drude model of metals.

This paper presents a CPW-fed planar inverted cone antenna (PICA) for ultra-wideband (UWB) communication applications. The proposed PICA provides a conventional monopole type omnidirectional radiation pattern, and it utilizes the advantages of the coplanar-waveguide (CPW) to simplify the structure of the antenna into a single metallic level. To improve radiation characteristics, a tapered and corrugated ground plane is used. In addition, the PICA's radiating element with three self-similarity holes is attempted to enhance performance of the antenna. The simulated and measured results demonstrate that the proposed PICA achieves a broad impedance bandwidth from 1.3 GHz to 11GHz within the magnitude of S₁₁ (dB) less than -10 dB and maintains nearly omnidirectional radiation characteristics.

This paper presents the design of a novel dual-band unequal Wilkinson power divider. The proposed power divider can operate at arbitrary two frequencies without reactive components. The design and analysis of power divider are presented. The structure of the power divider and the formulas used to determine the design parameters have been given. Closed-form design equations are derived based on network theory. For verification, a microwave power divider operating at 1 and 2 GHz is fabricated, the experimental results show that the designed unequal power divider fulfills all the features of a conventional Wilkinson power divider.

The backscattering experiments of water surface by Ultra-High Frequency (UHF, 300 ~ 3000 MHz) Radar are presented in this paper. In order to study UHF radio propagation and backscatter mechanisms from fresh and salty water surfaces at a very low grazing angle, two experiments are carried out on Yangtze River bridge and cliff which face open sea with the same radar system. The physical parameters of different water surfaces are introduced as well as the signature of backscattered echoes.

Novel time-harmonic beam fields have been recently obtained by utilizing a non-orthogonal coordinate system which is a priori matched to the field's planar linearly-phased Gaussian aperture distribution. These waveobjects were termed tilted Gaussian beams. The present investigation is concerned with parameterization of these time-harmonic tilted Gaussian beams and of the wave phenomena associated with them. Specific types of tilted Gaussian beams that are characterized by their aperture complex curvature matrices, are parameterized in term of beam-widths, waist-locations, collimation-lengths, radii of curvature, and other features. Emphasis is placed on the difference in the parameterization between the conventional (orthogonal coordinates) beams and the tilted ones.

Location information is critical for the development of value-added location-based services, such as fraud protection, location-aware network access, person/asset tracking etc. Herein, a method for the enhancement of localization systems in terms of achieved accuracy is proposed, which can be applied to new as well as existing systems regardless the underlying localization technique. The method is based on modeling the position measurement error introduced by the localization algorithm using a polynomial approximation approach. Measurements results demonstrate the applicability of the proposed technique in enhancing accuracy in a low cost and efficient manner.

Waves arise in many physical phenomena which have applications such as describing the voltage along a transmission line and medical imaging modality of elastography. In this paper, estimating the parameters for two forms of lossy wave equations, which correspond to multi-mode and multi-dimensional waves, are tackled. By exploiting the linear prediction property of the noise-free signals, an iterative quadratic maximum likelihood (IQML) approach is devised for accurate parameter estimation. Simulation results show that the estimation performance of the proposed IQML algorithms can attain the optimal benchmark, namely, Cramer-Rao lower bound, at sufficiently high signal-to-noise ratio and/or large data size conditions.

The finite-difference frequency-domain (FDFD) method with the adaptive basis functions/diagonal moment matrix (ABF/DMM) technique is proposed in this paper for finite periodic linear arrays of inhomogeneous dielectric cylinders, in which the versatility of the FDFD method and the high efficiency of the ABF/DMM technique are combined. The method in this paper and the classical full-domain FDFD method are compared in the given numerical examples. The results obtained by the two methods respectively are in good agreement, but the computational times are largely reduced in the method in this paper.

We investigate the transmission properties of the Fibonacci quasiperiodic layered structures consisting of a pair of double positive (DPS), epsilon-negative (ENG) or/and mu-negative (MNG) materials. It is found that there exist the polarization-dependent transmission gaps which are invariant with a change of scaling and insensitive to incident angles. Analytical methods based on transfer matrices and effective medium theory have been used to explain the properties of transmission gaps of DPS-MNG, DPS-ENG, ENG-MNG Fibonacci multilayer structures.

A zero-bias dual-mode mixing antenna for wireless transponders is proposed in this paper. Designed over an Enhancement-mode Pseudomorphic HEMT (E-PHEMT), the mixer takes advantage of the device nonlinear characteristics around cold operation. Simple closed form expressions, obtained from time-varying circuit analysis, predict good conversion efficiency in two different operating modes without requiring DC bias. For validation, a lab prototype has been implemented and tested, to be finally integrated in a compact active printed antenna suitable for wireless sensor networks or other radio frequency identification (RFID) applications.

The essential cause of Multiple Sclerosis (MS) remains to be unknown until present. Although the relevance of racial, genetic, immunological and environmental causal factors has been accepted and expressed by various researchers, there has not been an elaborate study as to the essential cause of MS. This study aims to explain the importance of the environmental causal factor on the occurrence of MS compared to the racial, immunological and genetic factors. In this study, especially the Extreme Low Frequency (ELF) electromagnetic fields and electromagnetic fields at a frequency band (10⁹-10¹³) Hz in terms of dielectrophoretic effect on myelin in dispersive gray matter and white matter are regarded as the essential causal factor of MS regardless of the fact, whether their sources are artificial or natural. There are epidemiological and experiment-based studies that support this view. In order to support my view, I made use of several comparative studies and obtained computational data. Dielectrophoretic force in the human body, especially in gray and white matter can affect on the myelin basic proteins and be the cause of accumulating them.

Active microwave imaging techniques are aimed at reconstructing an unknown region under test by means of suitable inversion algorithms starting from the measurement of the scattered electromagnetic field. Within such a framework, this paper focuses on an innovative strategy that fully exploits the information arising from the illumination of the investigation domain with different configurations as well as radiation patterns of the probing sources. The proposed approach can be easily integrated with multiview techniques and, unlike multifrequency methods, it does not require additive a-priori information on the dielectric nature of the scatterer under test. A large number of numerical simulations concerned with 2D geometries confirms the effectiveness of the inversion strategy as well as its robustness with respect to noise on data. Moreover, the results of a comparative study with single-source methodologies further point out the advantages and potentialities of the new approach.

A disk-loaded monopolee array antenna with coplanar waveguide (CPW) feeding systems that has the capability of beam switching has been successfully demonstrated. The antenna utilises the advantages of CPW and the transmission line of input impedance equation and is integrated with RF/Microwave devices to enable beam switching in the elevated and azimuthal planes. The measured gain of the antenna in the direction of the open-circuited parasite element is in the range of 5.10 to 5.60 dBi. It has good input return loss at 2.45 GHz and produces useful gain in the direction of the open circuited element. The E- and H-plane patterns show that the beam can be steered by pin diodes switching.

In this article, a novel wideband planar monopole antenna for applications in 2.4 GHz WLAN and UWB bands is presented and investigated. The proposed antenna is composed of a gourd-like radiation element fed by a 50 Ohm microstrip line and a step-shaped ground plane. A pair of slot lines is etched symmetrically on the ground plane to obtain the 5 GHz band-notched characteristic, and the notched band can be tuned. The proposed antenna is successfully simulated, designed, and measured. The measured results agree reasonably with the simulated ones. According to the measured results, the proposed antenna yields a wide bandwidth ranging from 2.2 to 11 GHz for VSWR less than 2, except the notched band of 5.1-6.2 GHz for 5 GHz WLAN. Moreover, it exhibits nearly omnidirectional radiation patterns, stable gain, and small group delay variation across the operation band, which meets the requirements of 2.4 GHz WLAN and UWB applications.

In microwaves, ferrites are characterized by a tensorial permeability which represents their anisotropy under a constant magnetic field. We present, in this article, a rigorous study of the formulation of the transverse operator method (TOM) with an extension to the case of the guides of rectangular waves partially charged with longitudinally magnetized ferrite. We show the existence of the complex modes in these types of structures with ferrite. A good agreement of the constant of propagation with the literature is obtained.