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In this paper, the path losses between the Jeungdo and Heuksando transceivers located in the coastal areas of Korea are studied using the Advanced Refractive Prediction System simulation software based on the actual coastal weather database. Based on the simulated data, we propose a novel duct map that can effectively estimate the abnormal wave propagation characteristics by using the atmospheric refractive index dependent on altitude as well as the location parameters of Rx and Tx. To verify the proposed duct map, two representative atmospheric index samples are obtained from the 2017 weather database of the Heuksando weather forecast station, causing the abnormal path loss characteristics. The simulated path losses for abnormal conditions at the Rx point are 132.3 and 140.1 dB, respectively, and these results demonstrate that the abnormal radio wave propagation can effectively be predicted through the proposed duct map. [ABSTRACT FROM AUTHOR]

The meteorological elements will affect the propagation of the radio wave. These meteorological elements can be reflected by the atmospheric refractive index, which is derived from the pressure, temperature, relative humidity, and vapor pressure. Using the atmospheric sounding data, a real atmospheric refractive index model for an identified area can be obtained. Combined with the refractive index model, the atmosphere can be divided into layered media with different refractive index, and a numerical model can be established to indicate the wave propagation path. The numerical solution results are verified by the analytical solution and other presented model. Due to its high accuracy and computational efficiency, the proposed numerical model can be used to quickly illustrate the physical path of radio wave atmospheric propagation, providing theoretical guidance for related applications. [ABSTRACT FROM AUTHOR]

ABSTRACT In this article, a corrugated substrate integrated waveguide (CSIW) with no metallic vias is proposed, and its propagation characteristics are theoretically investigated via our numerical short-open calibration (SOC) de-embedding method. In our analysis, dominant operating modes in this CSIW at different frequencies are extensively discussed. Its complex propagation constant is derived to demonstrate its frequency-dispersive transmission and attenuation performance. Then, the design rules are described to analyze and design CSIW line. In final, the fabricated CSIW with the microstrip-line feeders are measured to validate the numerically de-embedded attenuation constant over a wide frequency range. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2456-2460, 2016 [ABSTRACT FROM AUTHOR]

ABSTRACT Human bodies have a variety of tissues and organs, and so it needs to be characterized as a radio-wave propagation medium to create a reliable wireless communication link. The radiation characteristics of printed monopole antenna and printed loop antenna for wireless-implantable body area network (WiBAN) applications are presented in this article. The two antennas are submerged into canola oil to mimic an implanted antenna in the human tissue. The tissue is considered a lossy environment and hence, it adversely degrades radiation characteristics of both antennas. Therefore, the RF transmission attenuation, dB can be used for characterizing the propagating wave from the submerged antennas to the free-air surface. The measured results show satisfactory performance and are in good agreement with the simulation. As indicated in the results, the attenuation rate from a lossy environment to the free space for the printed loop antenna (0.1 dB/mm) is smaller compared to that of printed monopole antenna (0.1-0.3 dB/mm). More so, the printed loop antenna is smaller in size (about 56%) compared to the printed monopole antenna, which suggests that the loop antenna is more suitable than the monopole for the WiBAN applications. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1270-1274, 2014 [ABSTRACT FROM AUTHOR]

A three-dimensional convex polyhedral beam-tracing method for modeling ultrawideband indoor radio channels is presented.The model enables a fast and unambiguous generation of all propagation paths between the transmitter and the receiver over an 850-MHz bandwidth. To validate the model, its results are compared with measurements. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:904-909, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26670 [ABSTRACT FROM AUTHOR]

This work introduces an integral equation formulation to model the radiowave propagation over inhomogeneous smoothly irregular terrain. The ground energy loss is estimated via the Leontovich boundary condition and the fast far-field algorithm accelerating technique is applied in order to improve the computational performance when solving the integral equation. The proposed formulation was implemented in a prediction software named SPRad, which was numerically tested with two measurement campaigns performed in Denmark and Brazil. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:26-31, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26473 [ABSTRACT FROM AUTHOR]

By using radar techniques over distances of 16 and 80 m, microwave propagation experiments revealed the presence of anomalous forerunners situated in advanced positions with respect to the main (luminal) peak. These results can be interpreted by a typical diffraction integral, which accounts for the existence of (fast) complex waves, which are usually considered only in the near-field region, but are still surviving beyond this limit. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26133 [ABSTRACT FROM AUTHOR]

In this study, heuristic uniform theory of diffraction coefficients are suited to account for scattering by lossy conducting wedges.The novel heuristic solution is determined from other previously developed heuristic coefficients, combining their characteristics to improve the estimation of radiowave propagation in urban scenarios. Slope diffraction is also considered to account for double-diffracted fields in consecutive wedges. Maliuzhinets' coefficients provide base solutions to validate the novel formulation. The novel solution is then applied to the wave propagation in a typical urban scenario, and results are compared against measurements provided in the literature. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2657-2662, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25557 [ABSTRACT FROM AUTHOR]

This article describes the design of a novel circularly polarized H-shaped microstrip-array antenna with a T-slot for dedicated short-range communication (DSRC) system roadside equipment (RSE: 5.850–5.925 GHz). The antenna system needs a correct radiation pattern, at the assigned communication area, without interference from the other radio wave propagation. The proposed antenna is designed to reduce the side lobe level (SLL) by using the proper distance for patch array and multilayer substrates for DSRC RSE. H-shaped patches are used for circular polarization (RHCP or LHCP) with a T-slot. The measured bandwidth of the fabricated antenna is from 5.830 to 5.939 GHz when the return loss < -10 dB. The measured axial ratio (RHCP) is 1.25–2.02 dB and gain is 15.62–15.94 dBi. The experimental 3-dB beam width (HPBW) in the E-plane and H-plane are 22.52° and 24.11° at 5.91 GHz, respectively. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1545–1548, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24369 [ABSTRACT FROM AUTHOR]

This article presents theoretical and/or experimental study of the propagation and radiation characteristics of dielectric-loaded axial-mode helical antenna at 8.985 and 10.0 GHz. Characteristic equations for the sheath helix model are derived for three different dielectric loadings viz. loading with two coaxial dielectric layers, single dielectric layer, and air. These equations are solved for the propagation constant and hence the phase velocity for n = 1 higher order spatial harmonic mode. The variation in phase velocity with wavelength normalized helix circumference is studied for different ratio of outer to inner helix radii, ratio of outer to inner radii of the dielectric tube containing a solid dielectric cylinder inside the helix, and the dielectric constant of the dielectrics used. The results for variation in phase velocity of the wave for n = 1 mode propagating in sheath helix with wavelength normalized helix circumference for pitch angle of 7° are compared with the available theoretical data. The theoretical expression for the radiation field of the helical antenna is obtained through the application of magnetic vector potential for n = 1 mode. The theoretical Eθ and Eφ patterns of the helical antenna with three different dielectric loadings are compared among themselves and also with respective experimental results at 8.985 and 10.0 GHz in X-band. The gain, input VSWR, and axial ratio of antenna with three different dielectric loadings are also measured at 8.985 and 10.0 GHz. The work presented here can provide useful design guidelines for development of optimum dielectric-loaded helical antenna, which may find potential application in satellite communication. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1195–1203, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24286 [ABSTRACT FROM AUTHOR]

This article deals with a fast numerical method for GPR simulation of great scenes. Electromagnetic wave propagation in heterogeneous media is analyzed using a finite-difference time-domain (FDTD)-based method. The use of a moving subdomain allows dealing with large scale and realistic B-scan or C-scan in a reasonable computational time. A simple and fast inversion method based on a coherent superposition of signal phases will also be exposed. The performances of this method for the localization and shape recovering of various buried objects will be pointed out. This process is very easy to implement and also has the advantage to be used for monostatic or multisensor radar records. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 796–802, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24153 [ABSTRACT FROM AUTHOR]

Metallic waveguides can be constructed with sidewalls consisting of metallic rods instead of sheets. The attenuation constants and bandwidths of such waveguides are calculated for a fixed cutoff frequency while the radii of the metallic rods are varied. The propagation losses are found to decrease when the radii of the rods is increased. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2942–2945, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23844 [ABSTRACT FROM AUTHOR]

This article presents a simplified approach for characterization of ultra wideband (UWB) through-the-wall propagation. The simplified approach requires spectrum analyzer rather than vector network analyzer. A minimum phase retrieval method based on Hilbert transform is used to retrieve the phase information. The proposed method is shown to be applicable to the insertion transfer function. While linear phase component cannot be retrieved, important factors for UWB receiver design such as group delay ripple and dispersion effect can be retrieved. In noisy channels, phase retrieval could be superior to direct phase measurements. Estimation of linear phase component can be achieved through matching the measured phase with the retrieved phase. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 465–470, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23107 [ABSTRACT FROM AUTHOR]

Classical theories such as the uniform theory of diffraction use analytical expressions for diffraction coefficients. These methods are convenient for canonical problems and objects much greater than the wavelength and enable to rise in frequency. For more complex and smaller scattering structures, rigorous methods as the finite difference time domain method is more suited. In this article, we present a new look on radiowave propagation prediction, combining the advantages of these two complementary methods. This article presents several studies aiming to evaluate the validity domain of this hybrid method in terms of far-field propagation conditions. Finally, an application to indoor channel modeling is presented. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1312–1320, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22431 [ABSTRACT FROM AUTHOR]

The propagation characteristics of double-layer SIW structures have been investigated in this paper. On the basis of the theory of resonance cavity and SIW, the simple theoretical formulas for the lower and upper frequencies in the passband have been found. The theoretical analyses have indicated that these two frequencies have much dependence on the width of SIW and the length of the coupling slot, the fractional bandwidth of the double-layer SIW structures can be controllable. Agreement between the simulation data and the calculated results from the formulas can be observed. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1459–1463, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22469 [ABSTRACT FROM AUTHOR]

The frequency selective characteristics of a new dielectric periodic structure composed of left-handed materials (LHM) are carefully investigated by a method, which combines the multimode network theory with the rigorous mode matching method. The variations of the frequency selective characteristics with structure parameters are presented and comparisons of propagation properties between right-handed materials and LHM gratings are also shown with some explanations. Guidelines for accurate design of the left-handed dielectric frequency selective surface are given. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 421–424, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22153 [ABSTRACT FROM AUTHOR]

To date, most numerical and experimental studies of metamaterials are limited to normally incident plane waves with the magnetic field parallel to the axis of the inductive structure. In this article, the reflected field response of three types of Split Ring Resonator (SRR) media are measured as a function of incident field polarization, angle of incidence and frequency, using an automated free space focused beam measurement system. The measured results are compared with simulated data generated using the experimentally retrieved complex permittivity and permeability tensors from normal incidence measurements. It is concluded that there is no classical Brewster angle (zero reflection for a given angle of incidence). However, we observe a reflection minimum for all angles of incidence in a small range of frequencies close to the plasmon frequency for all orientations of the SRRs for perpendicular polarization. This will indeed have important low observable applications. In parallel polarization, SRR media are transparent for small angles of incidence. For both polarizations, the effect of anisotropy becomes significant as the angle of incidence increases and a significant change in the reflected field is observed. Thus, considering the anisotropic nature of such metamaterials is important when designing applications. In this article, we also independently verify the assumed constitutive models and property retrieval using normal incidence measurements, using oblique incidence scans. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2619–2624, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21986 [ABSTRACT FROM AUTHOR]

This paper addresses the electromagnetic wave propagation in a set of waveguiding structures evolved from the H-guide, where at least one of the common double-positive (DPS) dielectric slabs is replaced by a double-negative (DNG) slab. A full-wave analysis for the modes propagating in each structure is presented. Unusual propagation characteristics, such as anomalous dispersion, mode bifurcation, super-slow modes, and both co-directional and contra-directional mode coupling, are reported. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 185–190, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21119 [ABSTRACT FROM AUTHOR]

Computational analyses are performed on a parallel-plate Blumlein line with a nonstandard width of the dielectric, as a way to mitigate against the dielectric breakdown. We report its effects on the electric field, propagation time of the transient effect, characteristic impedance of the line, and output pulse. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 220–225, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20950 [ABSTRACT FROM AUTHOR]

A Gaussian beam-tracking technique is proposed for physical indoor-propagation modeling. Its efficiency stems from the collective treatment of rays, which is realized by using Gaussian beams to propagate fields. The formulation of this method is outlined, the computation-time efficiency is discussed, and the simulation results are compared to those obtained using a commercial ray-tracing software (X-Siradif®). © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 378–381, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20829 [ABSTRACT FROM AUTHOR]

The probability-density function for waves propagating in a straight perfect electrical conductor (PEC) rough-wall tunnel is deduced from mathematical models of random electromagnetic fields. The field propagating in caves or tunnels is a complex-valued Gaussian random process, analyzed using the central-limit theorem. The probability-density function for single-modal-field amplitude in such a structure is Ricean. Since both the expected value and the standard deviation of this field depend only upon the radial position, the probability-density function, which indicates the power distribution, is a radially dependent function. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 44: 427–430, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20656 [ABSTRACT FROM AUTHOR]

The implementation of wireless local area networks (WLANs) inside buildings is growing rapidly. It is important to predict the indoor coverage zone. The propagation-prediction models proposed in recent years have paid attention to the effects of propagation and reflection. But in a small room with metallic furniture, diffraction is the main influence upon path loss. Propagation loss and the diffraction loss are considered in the propagation-prediction model that we propose in this paper. The simulation and measurement results are obtained in order to verify the feasibility of this model. The mean error between the measurement and simulation results is within 2 dB. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 44: 281–284, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20611 [ABSTRACT FROM AUTHOR]

A frequency-domain approach for propagation measurements and characterization of indoor ultra-wideband (UWB) channels is presented. The approach is based on measurement of the magnitude using a scalar network analyzer and retrieving the phase from the magnitude data using a Hilbert transform relationship. Extensive propagation data are collected in a frequency range of 1 to 12 GHz in two buildings on the Virginia Tech campus. Using the measured data, channel-characterization results are obtained and compared to those based on time-domain measurements. The statistical results for small-scale fading, the path-loss exponent, and signal quality are presented. The frequency-domain results are generally in good agreement with the time-domain results, and also reaffirm the immunity of UWB propagation to small-scale fading. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 44: 118–123, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20563 [ABSTRACT FROM AUTHOR]

The dispersion relations for metamaterial cylindrical guides are found and their Brillouin diagrams are drawn for different guide parameters. It is found that the transverse propagation coefficient of the first TMz mode and the first TEz mode can be either real or imaginary. The longitudinal propagation coefficient of the first TMz mode starts at zero frequency and ends at a frequency where it is equal to the wave-number of the surrounding dielectric medium, while the longitudinal propagation coefficient of the first TEz mode starts at this same frequency and afterwards grows indefinitely. The first hybrid mode of order one as well as subsequent modes are also studied. It is found that for the first TMz and TEz modes, the group velocity is almost constant, whether the transverse propagation coefficient is real or imaginary. Moreover, interesting coupling effects can be obtained by using adjacent metamaterial and dielectric cylindrical guides. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 44: 31–35, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20538 [ABSTRACT FROM AUTHOR]

Conventional geometrical database models (GDMs) in ray tracing require vectorization of building information, thus cannot achieve datum-extraction from line-based GIS maps efficiently, in which the building layouts are mainly stored in scalar lines. A novel GDM with an improved algorithm in 2D/2.5D cases is proposed according to this kind of map. A comparison between the simulation and measurement results verifies the validity of the new model and method. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 307–310, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20453 [ABSTRACT FROM AUTHOR]

The analysis of n-coupled transmission lines with nonuniform cross-section is often necessary in the design and simulation of high-speed integrated circuits. A new modal analysis technique is presented, illustrating how a 2n-port coupled nonuniform line structure can be broken down into a set of n uncoupled 2-port nonuniform lines. Modal propagation parameters and modal transformation matrices are retrieved from the entries of the ABCD-matrix representation of the n-coupled line structure. An application concerning a tapered transmission-line system typically found in chip-carrier interconnections is provided as an example. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 186–189, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20415 [ABSTRACT FROM AUTHOR]

We propose a tensor product derivative matching (TPDM) method to restore the accuracy of high-order finite difference time-domain (FDTD) schemes of computational electromagnetics (CEM) with material interfaces in two spatial dimensions (2D). By making use of fictitious points, the TPDM method locally enforces the physical-jump conditions at material interfaces in a preprocessing stage to arbitrarily high orders of accuracy in principle, based on a structured grid. The proposed method encompasses a variety of schemes of different orders in a single code. In fact, numerical orders from 2 to near 16 are confirmed in the present study. To the best of our knowledge, such high orders have not been reported in the literature for CEM problems involving material interfaces. The limitation and applicability of the present scheme are also analyzed in detail. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 69–77, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20378 [ABSTRACT FROM AUTHOR]

A TLM model suitable to simulate the propagation of electromagnetic waves in Tellegen media is presented. The angle tilt between electromagnetic field vectors, the intrinsic impedances and the effective parameters of the medium are computed. The results for a monochromatic source are in very good agreement with the analytical solution. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 438–441, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11404 [ABSTRACT FROM AUTHOR]

In this paper, an efficient numerical simulation technique is introduced to extract the propagation characteristics of interconnects over lossy substrate structures. This approach is based on a compact-form FDFD method in conjunction with the two-step Lanczos (TSL) technique. The efficiency and accuracy of the algorithm are demonstrated through the simulation of several lossy transmission-line structures. [ABSTRACT FROM AUTHOR]

At millimeter-waves, home furniture's and objects' dimensions can be equal or superior to the wavelength. A comparison between propagation measurements conducted within a residential house for two configurations, furnished and empty, underscores the influence of the furniture on millimeter-wave propagation. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 39: 230–233, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11177 [ABSTRACT FROM AUTHOR]

Using the method of unidirectional waves, we numerically solve a wave equation that describes the vector propagation of a femtosecond laser pulse of few optical cycles in a uniaxial crystal. Propagation of the pulse in the direction normal to the optical axis is studied, taking into account both the second- and third-order nonlinearity of the crystal. Conversion efficiency as a function of crystal length, pump intensity, and pulse duration is studied. As an example, the propagation of a femtosecond laser pulse of τ = 10 fs duration at λ = 810 nm in a 12-μm thick LiNbO3 crystal is numerically modeled. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 280–285, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10742 [ABSTRACT FROM AUTHOR]

With advancements in microelectronics, interest in electromagnetic interference and compatibility in high-speed circuits has greatly increased in the engineering community, and application of computational electromagnetics to electromagnetic interference and compatibility (EMI/EMC) engineering has become an emerging technology. Termination, via, and crosstalk on interconnection lines raises EMI problems in high-speed circuits and requires attention during design phases for signal integrity. This paper analyzes signal propagation effects among different parts of high-speed interconnection lines using the finite-difference time-domain (FDTD) method. The mechanism and the effectiveness of control measures are examined, which can be applied to high-speed circuit designs. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 416–420, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10624 [ABSTRACT FROM AUTHOR]

An exact matrix polynomial series solution for oblique propagation in a cholesteric liquid crystal, reported in this journal some years ago, was numerically implemented. After a slight reformulation, it was found that numerical results can be accurately and quickly obtained with a simple desktop computer. With the high accuracy available, boundary value problems can be solved very easily. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 397–400, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10618 [ABSTRACT FROM AUTHOR]

A novel design for 2D isotropic left-handed metamaterials is presented. One of the main advantages of our proposal is that all the metallizations are placed at parallel stratified planes. Thus, this design can be realized by means of the well known, commonly used planar technology. An analytical model is provided for the analysis of this new metamaterial. Numerical results obtained by using this model are validated by experimental simulations. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 405–408, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10620 [ABSTRACT FROM AUTHOR]

This paper presents the results of a measurement campaign carried out with the aim of analysing the impact of people movement and activities on the indoor radio propagation channel at the frequency of 1.8 GHz. For that, the temporal variations of the channel between fixed terminals are measured in several propagation environments, in which usually different degrees of activity take place, allowing the definition of different canonical environments. From the measured data, the figures and statistical parameters that characterise each of the environments under study are extracted and analysed, in order to be able to associate the results obtained with the density of motion and extrapolate that information to other similar environments. The results can be useful for the design of new systems such as WPANs and for the development of a model that considers both the effects of spatial and temporal variations. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 132–137, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10537 [ABSTRACT FROM AUTHOR]

The main drawback of the coupled-mode method is the poor convergence and accuracy of the discontinuous field components. The greater the discontinuity, the worse these problems become. This Letter presents an improvement of the method, allowing this drawback to be minimized. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 408–414, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10337 [ABSTRACT FROM AUTHOR]

This Letter presents the measured time-delay characteristics of UHF radio propagation channels in room environments. The measurements used the swept-frequency technique with a different calibration method. The measured frequency bands include 2.4 GHz, 1.8 GHz, and 900 MHz. The particular interest is devoted to 2.4 GHz; the other two frequency bands were selected for comparison purpose. A simple channel model is derived from the measurement results. The in-room wideband propagation model is believed to be useful for BER simulation, modem scheme evaluation, and system design. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 115–119, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10248 [ABSTRACT FROM AUTHOR]

In this paper, we derive the main propagation characteristics and the polarization properties of plane waves propagating inside a nonlocal bianisotropic medium. An original condition of circular polarizability is also derived and studied. The nonlocal omega medium can, in principle, be thought of as a spreading of a large number of nonlocal omega elements in an otherwise simple isotropic dielectric host medium. A nonlocal omega element is an electrically conducting microstructure having its stem parallel to the electric field at a given point, and its loop axis parallel to the magnetic field at another point that is somewhat displaced from the first along the direction of the wave propagation. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 183–186, 2002. [ABSTRACT FROM AUTHOR]

This paper focuses on the calculation of radio loss in forest environments. In the study, an optimum four-layered forest model is proposed for the calculation of radio loss in forest environments. This optimum four-layered forest model is obtained by modifying a commonly used model consisting of homogeneous and isotropic dielectric layers placed over a conducting flat earth. The dielectric constant of tree trunks is obtained from published papers, and the equivalent dielectric constant of the tree canopy is calculated with the equivalent dielectric constant technique. After comparing the numerical results with those obtained from measurement data, it is found that there is good agreement between the numerical results and the measurement data. Based on the numerical results, an empirical formula is developed by using the least square curve-fitting method. This empirical formula is suitable for the calculations of radio loss in forest environments in a frequency range of 1–100 GHz. This formula also provides a simple, fast, accurate, and inexpensive method for calculating the radio loss in forest environments. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 474–480, 2001. [ABSTRACT FROM AUTHOR]

A rigorous analytical estimation is made of the propagation of power through a highly bent step-index parabolic cylindrical waveguide (PCW), the bending being across the direction of electromagnetic (EM) wave propagation. The scalar field approximation is employed for the analytical treatment. The general expression for power in the waveguide core is derived under the condition of vanishing refractive-index (RI) difference of the guide. The power patterns are shown for two different waveguide dimensions, and corresponding to different azimuthal modal indexes. The presented analysis is rigorous in the sense that no approximation is used to determine the representative functions for fields. It is found that an almost equal amount of power is carried by the bunched modes in thinner PCWs, and this feature affects guides having a higher thickness where the modes are less tightly bunched together. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 407–410, 2001. [ABSTRACT FROM AUTHOR]

In this letter, the dispersion characteristics and energy configurations of a cylindrical partially filled waveguide or lossy multilayered rod shielded by a metallic enclosure are presented for several modes. These parameters are obtained by a numerical simulation based on the residues theory. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 192–195, 2001. [ABSTRACT FROM AUTHOR]

An atmosphere of rain offers a dispersive medium for the propagation of radio signals above 10 GHz. The effect of dispersion, in terms of differential attenuation and phase dispersion, is insignificant for narrowband signals. Signals modulated with very short pulses can have a wide bandwidth over which dispersion will be appreciable, causing significant signal distortion. The propagation of pulsed signals under varying propagation conditions has been studied with the Fourier transform technique. The transfer function of the rain atmosphere is obtained using propagation models that include clear-air effects and scattering effects due to raindrops. The carrier signal at 30 GHz is considered to be modulated by a raised-cosine pulse with a base bandwidth of 1–3 GHz. A technique for the mitigation of pulse distortion using an FIR filter is presented to restore the distorted pulse to its original shape and position to a significant extent. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 105–109, 2001. [ABSTRACT FROM AUTHOR]

The present paper computes the normalized phase constant, dielectric loss, and conductor loss of the voltage-controlled Schottky-contact microstrip line using the variational method based on the single-layer reduction (SLR) formulation. Results computed by the SLR formulation show very good agreement with the experimental results, both in the normalized phase constant and total losses with 2.0% and 0.01 dB/mm, respectively. The present formulation can also handle a greater number of dielectric layers. The model is suitable for the CAD of Schottky-contact microstrip structures. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 341–344, 2001. [ABSTRACT FROM AUTHOR]

Three-dimensional indoor radio-wave propagation is accurately modeled by solving the volume electric-field integral equation (VEFIE). The integral equation is discretized by the method of moments (MoM), in which the building walls, ceilings, floors, as well as any internal obstacles are represented by a collection of small volumetric cells. This discretization is capable of modeling a 3-D room structure to fine details. The solution to the MoM matrix equation is facilitated by the multilevel fast multipole algorithm (MLFMA), which significantly reduces memory requirements and CPU time. Numerical examples are shown to demonstrate the accuracy of the solution and the capability of modeling dielectric structures of nearly realistic sizes. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 168–175, 2001. [ABSTRACT FROM AUTHOR]

A ray-tracing model based on the application of the uniform theory of diffraction (UTD) and geometrical optics (GO) for modeling the propagation in microcellular urban scenarios has been implemented. A comparison with the simulation of published results validates our model. This model has been used to analyze some propagation characteristics (path loss and rms delay spread) in two street-corner environments—regular and chaflane street corners. The study of the environments of the two corners shows that differences in the predictions are basically caused by the rays reflected on the walls of the chaflane corners. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 139–142, 2001. [ABSTRACT FROM AUTHOR]

In this paper, the eigenmode expansion technique is proposed to analyze the pentagonal waveguide for high-power microwave transmission. The analysis is implemented by expanding the electromagnetic fields inside a pentagonal waveguide with the infinite summation of the cylindrical waveguide modes. To obtain the numerical cutoff wavelength, the infinite summation has to be truncated, and then the point-matching technique is used on the boundary. Once the linear equation is obtained, which is the function of the cutoff wavenumber, the determinant about the eigenvalue is solved. The numerical results are in good agreement with those published. The propagation characteristics of the pentagonal waveguides, such as attenuation constant, power-handling capability, and characteristic impedance, are also analyzed. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 27: 125–129, 2000. [ABSTRACT FROM AUTHOR]

Wave coupling in the coupling section of a dielectric optical waveguide is discussed using even- and odd-mode analysis. The dispersion relations of different modes were obtained by solving Maxwell equations. The two-dimensional finite-difference in time-domain method was implemented to solve these equations. The even and odd modes were characterized by applying different excitation sources. A large number of time steps were taken to reveal the fine structure of the propagation modes. The propagation constants of these modes at the coupling frequency were calculated, and the optical-coupling length was determined. The result is in good agreement with those obtained by the Marcatili method. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 26: 234–237, 2000. [ABSTRACT FROM AUTHOR]

A perturbation technique is developed for the theoretical evaluation of the high-frequency quasi-TEM wave-propagation parameters of a cylindrical conductor placed above a longitudinally nonhomogeneous ground with a random conductivity profile. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 26: 166–169, 2000. [ABSTRACT FROM AUTHOR]

A calibration scheme is presented for synthesizer phase fluctuations in virtual antenna array measurements for wideband mobile radio channel sounding. The standard deviation of the direction-of-arrival error is calculated from the Allan variance of frequency synthesizers. Estimated errors for a 5.3 GHz channel sounder are less than 1°. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 26: 183–187, 2000. [ABSTRACT FROM AUTHOR]

A study of urban channel characteristics is carried out using the shooting and bouncing ray technique. Propagation characteristics are generated from the simulation, and are compared to measurement results for the downtown area of Austin, TX, at 1.9 GHz. Antenna diversity studies are also carried out using the simulation. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 24: 396–399, 2000. [ABSTRACT FROM AUTHOR]