Precise modeling of radio propagation is necessary for experiencing the benefits of wireless technology for indoor environments. Among many modeling techniques, the ray tracing based prediction models become popular for indoor wireless radio propagation characterization. Though the ray tracing models are popular, their key deficiency is the slower performance. In this paper, an accelerated technique for three dimensional ray tracing using Adelson-Velski and Landis (AVL) tree data structure is introduced. Here, the AVL tree data structure is coupled with the concepts of quadrant eliminating technique (QET) and nearest neighbor finder (NNF) for optimization and fast characterization of indoor wireless communication. Surface intersection scheme (SIS) is also introduced for optimizing the ray-object intersection time. The AVL tree is used for the effective handling of the objects and environments relative information. The QET technique decreases the ray tracing time by omitting unnecessary object, while NNF decreases the ray-object intersection time by finding the nearest object in an efficient technique. For the validation of the superiority of the proposed technique, a detailed comparison is made with the existing techniques. The comparison shows that the proposed technique has 81.69% lower time consumption than the existing techniques.

A novel printed monopole antenna covering 2.4-2.484 GHz (Bluetooth), 2.5-2.69 GHz (IMT-E) and 3.1-10.6 GHz (UWB) frequency bands is presented. The entire frequency bands are obtained by a modified U-shaped radiator and a modified ground plane. To prevent possible interference between UWB systems and other existing wireless systems such as WLAN and WiMAX, a SCRLH resonator structure is placed next to the feed line. Characteristics of the Bluetooth and IMT-E bands are further enhanced by two quarter-wavelength strips added on each side of the radiator. The proposed antenna can be easily printed on a 1.6-mm-thick FR4 substrate with dimensions of 30 × 41 mm². Simulation and experimental results show that the antenna yields an impedance bandwidth of 2.3-2.8 and 3-12 GHz with -10 dB reflection coefficient, except for the dual notched bands of 3.2-3.6 for WiMAX and 4.9-6.1 GHz for WLAN. The electrical characteristics in frequency and time domain show suitability of this antenna for use in UWB systems.

Bionics principle is applied to frequency selective surface (FSS) design in this paper. To authenticate the method, a novel bionic and miniaturized FSS is proposed by use of a model of alternate phyllotaxis. The simulated and measured results show that the proposed FSS has a much smaller size and maintains other FSS-related performances. To study the applications of the novel bionic FSS in practice, it is used for the ground plane of an antenna array to reduce the antenna radar cross section (RCS). Compared to a reference antenna, the antenna with bionic FSS has lower RCS and favorable radiation performance. Hence, applying bionics principle to FSS design and antenna RCS reduction is proved feasible, which will serve as a good candidate for the future design of FSS and antennas with or without a requirement of RCS control.

This paper presents a new type of wideband bandpass filter (BPF) with quasi-elliptic frequency response by using proposed stubs loaded anti-parallel coupled-line. With different loads, the proposed stubs loaded anti-parallel coupled-line has different numbers of transmission zeros (TZs). These TZs are symmetrical along the designing frequency f₀. By using a quarter-wavelength parallel coupled-line to connect two proposed stubs loaded anti-parallel coupled-line, three wideband BPFs centered at f₀ = 1.575 GHz with quasi-elliptic frequency response are successfully designed. Good agreements between the simulations and measurements can be observed. The measured results also exhibits that the fabricated BPFs have the merits of low in-band insertion loss, good in-band return loss, sharp passband selectivity and high out-of-band rejection.

In recent years, Artificial Neural networks (ANNs) have been intensively employed to build smart model of microwave devices. In this paper a characterization of lossy SIW resonators by means of Multilayer Perceptron Neural Networks (MLPNNs) on Graphics Processing Unit (GPU), is presented. Once properly selected and trained, a MLPNN can evaluate the lossy SIW resonator's resonant frequency f_r and the pertaining quality factor Q at a shorter time than the full-wave rigorous model. In this way, fast parametric models of SIWstructures to employ for the design and optimization of microwave devices, exploiting the computational power of GPUs, can be obtained.

In this paper, we present a new design of a compact tri-band unequal power divider, which is composed of a circular-coupling power divider and a triple-band resonator. The unequal power dividing characteristic is realized by two circular shaped microstrip lines coupled through a circular shaped slot. The triple-band resonator, which comprises a conventional half-wavelength resonator, a short stub and an open stub, deals with the triple-bandpass performance. The proposed tri-band power divider with 1:1.6 output power ratios working at 3.4 GHz, 4.2 GHz, and 5.25 GHz is simulated and fabricated, and good agreements between the simulated and measured results are observed.

A novel suspended twin-core fiber (STCF) based on a single-nanoweb structure for optical switching is proposed. The singlenanoweb structure of the STCF is an ultrathin glass membrane (nanoweb) suspended in air and adhered to the inner ring of a glass fiber capillary, which substantially provides a built-in transducing mechanism to boost the pressure-induced index change in the fiber core region of the STCF. Two fiber cores locate symmetrically in the center of the nanoweb, resulting to the mode coupling for the guiding light in the STCF. Optical and mechanical properties of the proposed STCFs under different pressure force are numerically investigated. Optical switching based on the STCF is achieved by controlling the pressure force applied to the STCF. Our simulations show that optical switching from one core to the other in the STCF is realized based on a low switching force of only 8 N. The performances of the optical switching based on STCFs with different structure parameters are presented.

The problem of the motion of a magnetic field due to the motion of a permanent magnet has been subject of scientific controversy for many decades. However, the similar question, pertaining to the motion of an electric field due to the motion of a permanent charge, has been neglected by the scientific community, tacitly admitting this specific purely kinematical phenomenon. Such an evidently skew position is under theoretical consideration on an experimental ground. It is shown a profound symmetry between electro-kinematics on the one hand and magneto-kinematics on the other, and also the radical dissimilarity of both from electrodynamics.

Consider a plane wave incident on a multilayered planar anisotropic structure composed of conventional materials and metamaterials and surround by two half-spaces. In this paper, we aim to prove three theorems which indicate a kind of duality in these structures. Assume an arbitrarily polarized plane wave obliquely incident on the structures. Theorem 1: Assume that an arbitrarily polarized plane wave is obliquely incident on the structure. Now each layer is filled with by dual media according to the interchanges DPS ↔ DNG and ENG ↔ MNG. Then, the reflection (R) and transmission (T) coefficients of the structure become the complex conjugates of their counterparts. Consequently, the reflected power and transmitted power from the structure are the same for the two dual cases of anisotropic media. Theorem 2: If the interchanges DPS ↔ DNG and ENG ↔ MNG are made in all the layers except in the half spaces on the two sides of the multilayer structure (which is more realizable), then the reflection coefficients become complex conjugates and the reflected power remains the same. Theorem 3: If the structure is backed by a perfect electric conductor and the media interchanges DPS ↔ DNG and ENG ↔ MNG are made in the layers, then the reflection coefficients of the two dual structures become complex conjugates of each other, and the reflected powers are equal. Independent of wave frequency, the number of layers, their thickness, and the type of polarization, these theorems hold true in case of any change in any of these conditions. In the last section, some examples are provided to verify the validity of the proposed theorems.

We incorporate high-order symplectic time integrators into multiresolution time domain (MRTD) schemes. The stability and numerical dispersion analysis are presented. The proposed scheme preserves the symplectic structure of Maxwell's equations and can be easily implemented in program codes. Compared to Runge-Kutta (RK)-MRTD, the suggested scheme is more accurate in long-term simulations and requires less computational resource.

In this paper a novel synthesis procedure is presented to achieve optimum solution for UWB filter parameters. It is found that the narrowband approximation is not valid for any arbitrary powered rational type filtering function. For wider bandwidths frequency dependent terms have significant effects on the frequency response. Hence, extracted filtering function cannot be mapped to generalize Chebyshev polynomials. This paper will provide exact synthesis procedure for step impedance resonators (SIR's) type UWB bandpass filters. To validate the synthesis procedure prototypes are designed and fabricated. Simulated and measured results show good agreement with proposed theory.

In this paper, we propose a method to use 1-D dielectric slabs, instead of metallic Frequency Selective Surfaces (FSSs), to produce Partially Reflective Surfaces (PRSs) with positive reflection phase gradients. The structure is realized by a single kind of dielectric substrate. It is modeled as cascaded transmission lines and then analyzed by virtue of the Smith Chart from the perspective of impedance transformation. A PRS designed by this approach is then applied to the realization of a wideband EBG resonator antenna operating at Ku band which is fed by a slot-coupled patch antenna. The calculated results indicate that the antenna possesses a relative 3 dB gain bandwidth of 22%, from 14.1 GHz to 17.6 GHz, with a peak gain of 17 dBi. The impedance bandwidth for the reflection coefficient (S₁₁) less than -10 dB, is from 14 GHz to 17.7 GHz, well covering the 3 dB gain bandwidth. A prototype has been fabricated and measured, and the experimental results well validate the simulation. The design method developed here is significantly effective, and can be easily adopted for antenna designs at other frequencies.

Dual-band metamaterial absorber (MA) with polarization independency based on omega (Ω) resonator with gap and octa-star strip (OSS) configuration is presented both numerically and experimentally. The suggested MA has a simple configuration which introduces flexibility to adjust its metamaterial (MTM) properties and easily re-scale the structure for other frequencies. In addition, the dual-band character of the absorber provides additional degree of freedom to control the absorption band(s). Two maxima in the absorption are experimentally obtained around 99% at 4.0 GHz for the first band and 79% at 5.6 GHz for the second band which are in good agreement with the numerical simulations (99% and 84%, respectively). Besides, numerical simulations validate that the MA could achieve very high absorption at wide angles of incidence for both transverse electric (TE) and transverse magnetic (TM) waves. The proposed MA and its variations enable myriad potential applications in medical technologies, sensors, modulators, wireless communication, and so on.

Since the system-level package was proposed, the electronics industry has increasingly attached importance to both directly relevant and related issues, and the scope of system-level package use has increased. Creating more complex system-level package structures, thereby leading to the design of overall electrical effects, requires more electromagnetic simulation resources, and therefore a great deal of time in the design process. The main purpose of this paper is to analyze the effects of system-level packaging, and to establish systems-in-package in accordance with electrical specifications. Using a segmented approach, this paper also builds an overall model for designers to predict electrical characteristics, thus shortening the product development schedule. In this paper, the transmission effects of a substrate are analyzed by changing the length of the substrate transmission line, with or without a thermal ground ball and ground ring. Previously established package IP are cascaded to establish the model of the package substrate, which verifies the feasibility of the package IP. We then analyze the characteristics of the interference between chips and package using an integrated passive device, and propose a complete package equivalent circuit model.

One of the most promising alternative imaging modalities for breast cancer detection involved the use of microwave radar systems. A critical component of any radar-based imaging system for breast cancer detection is the early-stage artifact removal algorithm. Many existing artifact removal algorithms are based on simplifying assumptions about the degree of commonality in the artifact across all channels. However, several real-world clinical scenarios could result in greater variation in the early-stage artifact, making the artifact removal process much more difficult. In this study, a range of existing artifact removal algorithms, coupled with algorithms adapted from Ground Penetrating Radar applications, are compared across a range of appropriate performance metrics.

In this study, we suggest and experimentally validate a methodology for fast and optimized design of dual-band implantable antennas for medical telemetry (MICS, 402-405 MHz, and ISM, 2400-2480 MHz). The methodology aims to adjust the design of a parametric dual-band antenna model towards optimally satisfying the requirements imposed by the antenna-fabrication procedure and medical application in hand. Design is performed in a systematic, fast, and accurate way. To demonstrate its effectiveness, the proposed methodology is applied to optimize the parametric antenna model for intra-cranial pressure (ICP) monitoring given a specific antenna-fabrication procedure. For validation purposes, a prototype of the optimized antenna is fabricated and experimentally tested. The proposed antenna is further evaluated within a 13-tissue anatomical head model in terms of resonance, radiation, and safety performance for ICP monitoring. Extensive parametric studies of the optimized antenna are, finally, performed. Feasibility of the proposed parametric antenna model to be optimally re-adjusted for various scenarios is demonstrated, and generic guidelines are provided for implantable antenna design. Dual-band operation is targeted to ensure energy autonomy for the implant. Finite Element (FE) and Finite Difference Time Domain (FDTD) simulations are carried out in homogeneous rectangular and anatomical head tissue models, respectively.

The propagation of light in an anisotropic impedance-matched metamaterial is studied in the frame of geometrical optics. We prove that directions of fields D, B and v (ray velocity) are a triad of conjugate directions with respect to the inverse relative dielectric permittivity tensor and constitutes a local basis, whose reciprocal one is formed by directions of E, H fields and wave-vector k. Consequently, both dual bases are intrinsically related to the physical properties of medium. We have identified these bases with direct and reciprocal bases of a curvilinear coordinates system, showing that physics defines geometry. This identification provides a powerful tool to solve two kinds of problems (direct and inverse ones) that currently arise: In direct problems, medium properties are given and it suffices to know ε = μ tensor at every point, to obtain the wave structure. In inverse problems, medium properties must be found for the rays to propagate along prescribed trajectories. The procedure is applied to an illustrating example.

In this paper, the equivalent cable bundle method (ECBM), an efficient simplified modeling method of the complex cable bundles, is modified for crosstalk prediction of complex cable bundles within uniform structure with arbitrary cross section. The foremost attributes of the modified method are a) the cable bundle within uniform structure with arbitrary cross section can be mapped to equivalent cable bundle above an infinite perfect electric conductor ground plane during the equivalence procedure, b) the culprit and victim conductors are divided into two groups separately during the grouping process, denoted as the culprit group and victim one, which do not participate in the equivalence procedure compared with the original ECBM for crosstalk problem, c) an effective eight-phase procedure is established to define the electrical and geometrical characteristics of the reduced cable bundle model. Numerical simulations performed on a selected cable bundle surrounded by a rectangular cavity illustrate the efficiency and the advantages of the method. This method is considered as a key step for the ECBM to find wide applications in real systems.

This paper proposes a novel method to make large area metamaterials on arbitrary planar hard or flexible substrates, in-situ. The method is based on painting the desired substrate with metallic and dielectric paints through a patterned stencil mask. We demonstrate this painting approach to fabricate ultra-thin perfect electromagnetic absorbers based on metamaterials at X-band frequencies (8-12 GHz) with paper based stencils, silver ink and latex paint. Measurement results on absorber samples made with this process shows absorption of 95%-99%, in close agreement with simulation results. The proposed painting approach is a simple low cost additive manufacturing process that can be used to realize metamaterial based frequency selective surfaces and filters, radar absorbers, camouflage screens, electromagnetic sensors and EMI protection devices.

In this paper, we investigate an expectation-maximization (EM) maximum likelihood (ML) algorithm of direction finding (DF) for bistatic multiple-input multiple-output (MIMO) radar, where it is shown that the DF problem can be described as a special case of ML estimation with incomplete data. First, we introduce the signal and the noise models, and derive the ML estimations of the direction parameters. Considering the computational complexity, we make use of the EM algorithm to compute the ML algorithm, referred to EM ML algorithm, which can be applied to the arbitrary antenna geometry and realize the auto-pairing between direction-of-departures (DODs) and direction-of-arrivals (DOAs). Then the initialization is considered. In addition, both the convergence and the Cramer-Rao bound (CRB) analysis are derived. Finally, simulation results demonstrate the potential and asymptotic efficiency of this approach for MIMO radar systems.