Vol. 77
Latest Volume
All Volumes
PIER 177 [2023] PIER 176 [2023] PIER 175 [2022] PIER 174 [2022] PIER 173 [2022] PIER 172 [2021] PIER 171 [2021] PIER 170 [2021] PIER 169 [2020] PIER 168 [2020] PIER 167 [2020] PIER 166 [2019] PIER 165 [2019] PIER 164 [2019] PIER 163 [2018] PIER 162 [2018] PIER 161 [2018] PIER 160 [2017] PIER 159 [2017] PIER 158 [2017] PIER 157 [2016] PIER 156 [2016] PIER 155 [2016] PIER 154 [2015] PIER 153 [2015] PIER 152 [2015] PIER 151 [2015] PIER 150 [2015] PIER 149 [2014] PIER 148 [2014] PIER 147 [2014] PIER 146 [2014] PIER 145 [2014] PIER 144 [2014] PIER 143 [2013] PIER 142 [2013] PIER 141 [2013] PIER 140 [2013] PIER 139 [2013] PIER 138 [2013] PIER 137 [2013] PIER 136 [2013] PIER 135 [2013] PIER 134 [2013] PIER 133 [2013] PIER 132 [2012] PIER 131 [2012] PIER 130 [2012] PIER 129 [2012] PIER 128 [2012] PIER 127 [2012] PIER 126 [2012] PIER 125 [2012] PIER 124 [2012] PIER 123 [2012] PIER 122 [2012] PIER 121 [2011] PIER 120 [2011] PIER 119 [2011] PIER 118 [2011] PIER 117 [2011] PIER 116 [2011] PIER 115 [2011] PIER 114 [2011] PIER 113 [2011] PIER 112 [2011] PIER 111 [2011] PIER 110 [2010] PIER 109 [2010] PIER 108 [2010] PIER 107 [2010] PIER 106 [2010] PIER 105 [2010] PIER 104 [2010] PIER 103 [2010] PIER 102 [2010] PIER 101 [2010] PIER 100 [2010] PIER 99 [2009] PIER 98 [2009] PIER 97 [2009] PIER 96 [2009] PIER 95 [2009] PIER 94 [2009] PIER 93 [2009] PIER 92 [2009] PIER 91 [2009] PIER 90 [2009] PIER 89 [2009] PIER 88 [2008] PIER 87 [2008] PIER 86 [2008] PIER 85 [2008] PIER 84 [2008] PIER 83 [2008] PIER 82 [2008] PIER 81 [2008] PIER 80 [2008] PIER 79 [2008] PIER 78 [2008] PIER 77 [2007] PIER 76 [2007] PIER 75 [2007] PIER 74 [2007] PIER 73 [2007] PIER 72 [2007] PIER 71 [2007] PIER 70 [2007] PIER 69 [2007] PIER 68 [2007] PIER 67 [2007] PIER 66 [2006] PIER 65 [2006] PIER 64 [2006] PIER 63 [2006] PIER 62 [2006] PIER 61 [2006] PIER 60 [2006] PIER 59 [2006] PIER 58 [2006] PIER 57 [2006] PIER 56 [2006] PIER 55 [2005] PIER 54 [2005] PIER 53 [2005] PIER 52 [2005] PIER 51 [2005] PIER 50 [2005] PIER 49 [2004] PIER 48 [2004] PIER 47 [2004] PIER 46 [2004] PIER 45 [2004] PIER 44 [2004] PIER 43 [2003] PIER 42 [2003] PIER 41 [2003] PIER 40 [2003] PIER 39 [2003] PIER 38 [2002] PIER 37 [2002] PIER 36 [2002] PIER 35 [2002] PIER 34 [2001] PIER 33 [2001] PIER 32 [2001] PIER 31 [2001] PIER 30 [2001] PIER 29 [2000] PIER 28 [2000] PIER 27 [2000] PIER 26 [2000] PIER 25 [2000] PIER 24 [1999] PIER 23 [1999] PIER 22 [1999] PIER 21 [1999] PIER 20 [1998] PIER 19 [1998] PIER 18 [1998] PIER 17 [1997] PIER 16 [1997] PIER 15 [1997] PIER 14 [1996] PIER 13 [1996] PIER 12 [1996] PIER 11 [1995] PIER 10 [1995] PIER 09 [1994] PIER 08 [1994] PIER 07 [1993] PIER 06 [1992] PIER 05 [1991] PIER 04 [1991] PIER 03 [1990] PIER 02 [1990] PIER 01 [1989]
2007-09-14
PIER
Vol. 77, 493-499, 2007
download: 114
Design of Miniature Planar Dual-Band Filter with 0° Feed Structures
Wei Xue Chang-Hong Liang DDD Li Jun-Wa Fan
A novel dual-band planar filter is proposed in this paper. It is shown that the two transmission bands can be excited and designed using proposed resonators which combine different sizes of open-loop resonators. The main resonators control the low-band resonant frequency and the sub resonators control the high-band resonant frequency. With 0 feed structures added, the frequency selectivity of the filter is greatly improved. And the proposed filter also has advantages as low insertion loss and miniature size. The measurement of the filter is in good agreement with the simulation.
DESIGN OF MINIATURE PLANAR DUAL-BAND FILTER WITH 0° FEED STRUCTURES
2007-09-14
PIER
Vol. 77, 425-491, 2007
download: 190
Central Force Optimization: a New Metaheuristic with Applications in Applied Electromagnetics
Richard Formato
Central Force Optimization (CFO) is a new deterministic multi-dimensional search metaheuristic based on the metaphor of gravitational kinematics. It models "probes" that "fly" through the decision space by analogy to masses moving under the influence of gravity. Equations are developed for the probes' positions and accelerations using the analogy of particle motion in a gravitational field. In the physical universe, objects traveling through threedimensional space become trapped in close orbits around highly gravitating masses, which is analogous to locating the maximum value of an objective function. In the CFO metaphor, "mass" is a userdefined function of the value of the objective function to be maximized. CFO is readily implemented in a compact computer program, and sample pseudocode is presented. As tests of CFO's effectiveness, an equalizer is designed for the well-known Fano load, and a 32-element linear array is synthesized. CFO results are compared to several other optimization methods.
CENTRAL FORCE OPTIMIZATION: A NEW METAHEURISTIC WITH APPLICATIONS IN APPLIED ELECTROMAGNETICS
2007-09-09
PIER
Vol. 77, 417-424, 2007
download: 110
Novel Design of Dual -Mode Dual-Band Bandpass Filter with Triangular Resonators
Li-Peng Zhao DDD Li Zhi-Xi Chen Chang-Hong Liang
A novel dual-mode dual-band bandpass filter based on conventional triangular dual-mode filter is designed in this paper. The filter has the characteristics of compact structure, low insertion loss and so on. Based on the current design schemes, the design of dualmode and dual-band filter can be integrated in a novel filter structure. Several attenuation poles in the stopband are realized to improve the selectivity of the proposed bandpass filter. The experimented results were in good agreement with simulated results.
NOVEL DESIGN OF DUAL -MODE DUAL-BAND BANDPASS FILTER WITH TRIANGULAR RESONATORS
0000-00-00
PIER
Vol. 77, 409-416, 2007
download: 101
Novel Dual-Mode Dual-Band Bandpass Filter Using Double Square-Loop Structure
Zhi-Xi Chen DDD Li Chang-Hong Liang
A dual-mode dual-band bandpass microstrip filter using double square-loop structure is proposed in this paper. Each of the square-loop forms a dual-mode resonator with controllable respective passband. Two tuning patches placed symmetrically at the side of the perturbation patch are used to change the higher passband frequency, while while keeping the lower invariable. Several attenuation poles in the stopband are realized to improve the selectivity of the proposed bandpass filter. The filter is evaluated by experiment and simulation with good agreement.
NOVEL DUAL-MODE DUAL-BAND BANDPASS FILTER USING DOUBLE SQUARE-LOOP STRUCTURE
2007-09-09
PIER
Vol. 77, 391-408, 2007
download: 660
Simplified Formulation of Dyadic Green's Functions and Their Duality Relations for General Anisotropic Media
Abdullah Eroglu Jay Kyoon Lee
A simplified method to obtain the complete set of the dyadic Green's functions (DGFs) for general anisotropic media is presented. The method is based on the k-domain representation of the fields in terms of wave matrices. The Fourier transformed Green's functions are calculated through the inverses of wave matrices. The inverses of the wave matrices, which lead to the final form of DGF, are obtained using dyadic decomposition technique. This facilitates the inverse operation significantly and gives DGFs clear vector representation, which helps their physical interpretation. The dyadic decomposition of the wave matrices has been presented for uniaxially anisotropic, biaxially anisotropic and gyrotropic media. The method of deriving DGF using the technique given in this paper is applied on a uniaxially anisotropic medium and verified with the existing results. It is shown that the knowledge of the inverse of one type of wave matrix is adequate to find the complete set of the dyadic Green's functions for a general anisotropic medium using the method presented. The duality relations of dyadic Green's functions are also developed. It is shown that once the dyadic Green's functions for one of the dual media are obtained, the DGFs for the other dual medium can be found by application of the duality relations shown in this paper.
2007-09-07
PIER
Vol. 77, 379-390, 2007
download: 458
Analysis and Design of a Rectangular Dielectric Resonator Antenna Fed by Dielectric Image Line through Narrow Slots
Asem Al-Zoubi Ahmed Kishk Allen Wilburn Glisson
Analysis and design of a narrow aperture coupled rectangular dielectric resonator antenna (DRA) fed by dielectric image line (DIL) are presented. The modal expansion method is used to describe the fields in the dielectric resonator side and the change in the modal voltage of the image line at the aperture is developed to analyze the single element DRA. The DIL is connected to the Xband rectangular waveguide through a waveguide transition and DIL tapering is used to match between the waveguide and the DIL.
ANALYSIS AND DESIGN OF A RECTANGULAR DIELECTRIC RESONATOR ANTENNA FED BY DIELECTRIC IMAGE LINE THROUGH NARROW SLOTS
2007-09-07
PIER
Vol. 77, 367-378, 2007
download: 151
Reduction of Crosstalk in Wavelength Division Multiplexed Fiber Optic Communication Systems
Ragini Tripathi Ramgopal Gangwar Nar Singh
In this paper two new methods to reduce the crosstalk in WDM systems are presented. These two methods along with the present methods are analyzed and their performances are compared. The proposed methods yield better results. Both signal power and optical signal power to noise power ratio (OSNR) improve significantly.
REDUCTION OF CROSSTALK IN WAVELENGTH DIVISION MULTIPLEXED FIBER OPTIC COMMUNICATION SYSTEMS
2007-09-03
PIER
Vol. 77, 357-365, 2007
download: 265
Measuring the Permittivity of Dielectric Materials Using STDR Approach
Gholamreza Moradi Abdolali Abdipour
This paper presents a new approach for measuring dielectric properties of materials. The proposed approach is based on applying the synthetic time domain reflectometry to a dielectric filled waveguide. The compromising measurement results show that this algorithm can be successfully applied for measuring other parameters of the materials. Also, the approach has been successfully applied to detect the discontinuities of as a multi-section microstrip line. This approach is very useful in measuring the electromagnetic parameters of the different liquids, gels, and solid materials.
MEASURING THE PERMITTIVITY OF DIELECTRIC MATERIALS USING STDR APPROACH
2007-09-03
PIER
Vol. 77, 343-356, 2007
download: 189
Novel Microstrip Triangular Resonator Bandpass Filter with Transmission Zeros and Wide Bands Using Fractal-Shaped Defection
Jian-Kang Xiao Qing-Xin Chu Sheng Zhang
Fractal microwave passive circuits are simple and novel structures that attract much attention recently, however, the fractal technique is dominantly applied in antennas. In this paper, some new characteristics of microstrip equilateral triangular patch resonator with fractal defection are analyzed, and novel fractal bandpass filters using equilateral triangular resonator are presented to implement high performances of multi-transmission zeros, wide passband and stopband, and low passband insertion loss as well as miniaturization. Using fractal defection in patch, multi higher order modes are inspired for coupling a much wider passband, and parasitical harmonics are effectively suppressed. A new bandpass filter with a wide passband of about 0.92 GHz (εr = 9.8) or 2.7 GHz (εr = 2.2), maximum passband insertion loss of less than 0.5 dB, and multi-transmission zeros at both sides of passband, and a second bandpass filter with wide passband and stopbands of more than 2 GHz are implemented. Compared with some literatures, sizes of the new filters reduced and performances are greatly enhanced. The proposed filters have compact and simple structures, small sizes, high selectivity and so on, and all these features are the requirement of wireless communication circuits.
NOVEL MICROSTRIP TRIANGULAR RESONATOR BANDPASS FILTER WITH TRANSMISSION ZEROS AND WIDE BANDS USING FRACTAL-SHAPED DEFECTION
2007-09-01
PIER
Vol. 77, 329-342, 2007
download: 152
A Numerical Study on Time- Reversal Electromagnetic Wave for Indoor Ultra-Wideband Signal Transmission
Shao-Qiu Xiao Jian Chen Bing-Zhong Wang Xiao-Fei Liu
In this paper, the propagation of ultra-wideband (UWB) pulse based on time reversal (TR) technique is studied by finitedifferent time-domain method in indoor environment. Time compression and spatial focusing of TR waveform are simulated and the propagation of multi-waveform string is analyzed. Then UWB wireless signal transmission based on TR concept is studied numerically. The studied results indicate that the UWB communication based on TR technique can obtain better Inter-Symbol Interference (ISI) and Co- Channel Interference (CCI) performance than traditional one because of its unique property.
A NUMERICAL STUDY ON TIME- REVERSAL ELECTROMAGNETIC WAVE FOR INDOOR ULTRA-WIDEBAND SIGNAL TRANSMISSION
2007-09-01
PIER
Vol. 77, 309-328, 2007
download: 358
Time Domain Analysis of Active Transmission Line Using FDTD Technique (Application to Microwave/mm - Wave Transistors)
Kambiz Afrooz Abdolali Abdipour Ahad Tavakoli Masoud Movahhedi
In this paper, an accurate modeling procedure for GaAs MESFET as active coupled transmission line is presented. This model can consider the effect of wave propagation along the device electrodes. In this modeling technique the active multiconductor transmission line (AMTL) equations are obtained, which satisfy the TEM wave propagation along the GaAs MESFET electrodes. This modeling procedure is applied to a GaAs MESFETs by solving the AMTL equations using Finite-Difference Time-Domain (FDTD) technique. The scattering parameters are computed from time domain results over a frequency range of 20-220 GHz. This model investigates the effect of wave propagation along the transistor more accurate than the slice model, especially at high frequencies.
TIME DOMAIN ANALYSIS OF ACTIVE TRANSMISSION LINE USING FDTD TECHNIQUE (APPLICATION TO MICROWAVE/MM- WAVE TRANSISTORS)
2007-08-30
PIER
Vol. 77, 285-307, 2007
download: 119
Scattering of Obliquely Incident Plane Wave by an Array of Parallel Concentric Metamaterial Cylinders
Bassem Henin Mohamed Al Sharkawy Atef Elsherbeni
A rigorous semi-analytical solution is presented for electromagnetic scattering from an array of parallel-coated circular cylinders of arbitrary radii and positions due to an obliquely incident TMz plane wave excitation. In order to check the validity of this technique, the radar cross-section of a single coated cylinder, a linear array of cylinders, and an arbitrary position array of cylinders are calculated and compared with available data in the literature. Furthermore, the near field is calculated to prove the validity of the boundary conditions on the surface of any cylinder with obliquely incidence wave. As an application, circular metamaterial cylinders are used to show the effect of metamaterial characteristics in altering the forward and backward scattering and in focusing the near field around the objects.
SCATTERING OF OBLIQUELY INCIDENT PLANE WAVE BY AN ARRAY OF PARALLEL CONCENTRIC METAMATERIAL CYLINDERS
2007-08-30
PIER
Vol. 77, 281-284, 2007
download: 164
Study on the Impedance-Matching Technique for High-Temperature Superconducting Microstrip Antennas
Shu-Fang Liu Xiao-Wei Shi Shao-Dong Liu
Impedance-Matching technique is in common use for antennas to broaden their bandwidth. Its application in hightemperature superconducting microstrip antennas is studied theoretically in this paper. It is found that employing an impedance-matching network directly to HTS microstrip antennas to broaden their bandwidth is of little significance.
STUDY ON THE IMPEDANCE-MATCHING TECHNIQUE FOR HIGH-TEMPERATURE SUPERCONDUCTING MICROSTRIP ANTENNAS
2007-08-30
PIER
Vol. 77, 273-280, 2007
download: 122
A Novel and Compact UWB Bandpass Filter Using Microstrip Fork-Form Resonators
Hui Chen Yu-Xing Zhang
A novel and compact ultra wideband (UWB) bandpass filter (BPF) with two transmission zeros near both passband edges of lower and higher frequency is proposed by using a new structure of fork-formresonators. The fork-formresonator generates a attenuation pole at the higher passband edge, lower insertion loss, wider bandwidth and compacter dimension, as compared with the traditional parallel unilateral-coupled resonator. A microstrip bandpass filter cascaded by two stages fork-formresonators with a 3-dB fractional bandwidth of 128% (from1.0 GHz to 4.6 GHz) is designed, fabricated, and tested. The measured characteristics of the filter agree with the theoretical simulations, and the measured results show good specifications which are very low insertion loss 0.5±0.3 dB within the passband and good return loss less than −15 dB from1.5 GHz to 4.0 GHz, respectively.
A NOVEL AND COMPACT UWB BANDPASS FILTER USING MICROSTRIP FORK-FORM RESONATORS
2007-08-30
PIER
Vol. 77, 267-272, 2007
download: 149
An Expression for the Radar Cross Section Computation of an Electrically Large Perfect Conducting Cylinder Located Over a Dielectric Half-Space
Xiao-Jie Chen Xiao-Wei Shi
A method is presented to calculate the monostatic Radar Cross Section (RCS) of an electrically large perfect conducting cylinder vertically located over a dielectric half-space using Physical Optics (PO) technique. The four-path modal method is used to approximate the influence of the half-space to the scattering mechanism. The comparison between the results calculated by this expression and that by Moment Method (MOM) show that the expression is effective and efficient.
AN EXPRESSION FOR THE RADAR CROSS SECTION COMPUTATION OF AN ELECTRICALLY LARGE PERFECT CONDUCTING CYLINDER LOCATED OVER A DIELECTRIC HALF-SPACE
2007-08-27
PIER
Vol. 77, 243-266, 2007
download: 153
Linear and Nonlinear Superimposed Bragg Grating: a Novel Proposal for All-Optical Multi-Wavelength Filtering and Switching
Hassan Ghafoori-Fard Mohammad Moghimi Ali Rostami
In this paper, the linear and nonlinear applications including optical filtering and switching of superimposed Bragg grating are presented. For realization of superimposed Bragg grating electrooptic effect is used. The introduced system acts as an optical chip. The induced superimposed index of refractions due to sampled electric potentials applied through metallic strips on electro-optically active core-cladding are investigated analytically and simulated numerically using the Transfer Matrix Method (TMM). It is shown that the applied electric field induces superimposed refractive index grating, which can be controlled using amplitudes and frequency contents of potential samples as well as optical waveguide parameters. Our proposed structure is analog programmable device for realization of many interesting optical signal conditioners such as optical filters, optical beam splitters, and many other special transfer functions in linear case. The proposed device is tunable and can be controlled using the applied potential parameters (samples) and easily satisfy dense wavelength division multiplexing (DWDM) system demand specifications. The electro-optic Pockels effect for generation of the superimposed gratings in this building block will be used. Then we propose an optical chip for performing the introduced functions. In practical cases, for realization of DWDM demands, we need very large number of potential samples approximately 3 to 4 orders of magnitudes. So, this type of block as optical controllable chip really from practical point of views is impossible and illegal. In this paper, we will present a simple approach for decreasing the number of efficient control samples from outside for managing the proposed tasks. Our calculations in this paper shows that with less than approximately 200 control pins, we can realize all of proposed practical ideas with acceptable precision. Also, with 3 samples per period, our design will cover 215 individual DWDM channels theoretically from 1.55um towards lower wavelengths and 325 channels for 4 samples per period case, which is infinity from practical point of views. All of transfer functions corresponding to these channels can be manipulated using applied potential samples. Also, as nonlinear applications of the superimposed Bragg grating multi-wavelength optical switching is presented. For this purpose the switching operation is illustrated first and then switching thresholds in the case of three predefined wavelengths are shown. Thus we illustrate numerical results for demonstration of the ability of the proposed structure. At the same time, we investigate effects of the parameters of the proposed structure such as the nonlinear refractive index and the grating length (number of layers) on switching performance including threshold intensity and slope of transition function. The proposed structure can be used as multi-wavelength switching applicable to DWDM and multi wavelength communication systems.
LINEAR AND NONLINEAR SUPERIMPOSED BRAGG GRATING: A NOVEL PROPOSAL FOR ALL-OPTICAL MULTI-WAVELENGTH FILTERING AND SWITCHING
2007-08-24
PIER
Vol. 77, 225-242, 2007
download: 166
Interaction of Dual Band Helical and PIFA Handset Antennas with Human Head and Hand
Mohammad Ali Ebrahimi-Ganjeh Amir Attari
Helical antenna and planar inverted-F antenna (PIFA) are two commonly used handset antennas. This paper presents a comprehensive study on the performance of a dual band PIFA and a dual band helical antenna designed for operating in GSM900 and DCS1800 frequency bands. Radiation patterns and VSWR of these antennas are computed in free space as well as in the presence of head and hand. The specific absorption rate (SAR) of the helical antenna is calculated and compared with that of the PIFA handset antenna. The peak average SAR in the head is compared with SAR limits in the safety standards and so the maximum radiation power of each antenna is determined. In addition, radiation efficiencies of these handset antennas are computed in the presence of head and hand. All numerical simulations are performed using the Ansoft HFSS software. Numerical simulations results are in good agreement with published measurement results.
INTERACTION OF DUAL BAND HELICAL AND PIFA HANDSET ANTENNAS WITH HUMAN HEAD AND HAND
2007-08-24
PIER
Vol. 77, 215-224, 2007
download: 109
Backscattering of Electrically Large Perfect Conducting Targets Modeled by NURBS Surfaces in Half-Space
Xiao-Jie Chen Xiao-Wei Shi
Backscattering Radar Cross Section (RCS) of electrically large targets is analyzed using Physical Optics (PO) approximation. The targets are located in a dielectric half-space,and modeled with Nonuniform Rational B-spline (NURBS) surfaces. The influence of the half-space is considered by the "four-path" model approximation. Results show the validity of the method.
BACKSCATTERING OF ELECTRICALLY LARGE PERFECT CONDUCTING TARGETS MODELED BY NURBS SURFACES IN HALF-SPACE
2007-08-24
PIER
Vol. 77, 193-214, 2007
download: 95
Double Statistical Distribution of Conductivity and Aspect Ratio of Inclusions in Dielectric Mixtures at Microwave Frequencies
Marina Koledintseva Richard DuBroff Robert Schwartz James Drewniak
An analytical model of a composite dielectric presented in this paper is the extension of Maxwell Garnett formulation. It takes into account the simultaneous statistical (Gaussian) distribution of conductivity and aspect ratio of inclusions. The inclusions are randomly oriented elongated conducting spheroids at concentrations below the percolation threshold. The formulation presented herein is limited to microwave frequencies. However, taking subtle frequencydependent effects that play important part at optical frequencies into account is straightforward. Some results of computations of microwave complex effective permittivity of composites with different input parameters have been obtained using analytical and numerical integration in Maple 10 software. It is shown how the parameters of the distribution laws - mean values and standard deviations of aspect ratio and conductivity - affect the resultant complex effective permittivity. The results of computations demonstrate that the most important factors affecting frequency characteristics of microwave effective permittivity are the mean values of the aspect ratio and conductivity. As for the standard deviations of aspect ratio and conductivity, their effects are the most noticeable in the transition between the static and optical limits of the Debye characteristic for the effective permittivity. There is almost no effect in the static and "optic" regions of the Debye curves.
DOUBLE STATISTICAL DISTRIBUTION OF CONDUCTIVITY AND ASPECT RATIO OF INCLUSIONS IN DIELECTRIC MIXTURES AT MICROWAVE FREQUENCIES
2007-08-24
PIER
Vol. 77, 181-192, 2007
download: 154
An Efficient Hybrid Swarm Intelligence-Gradient Optimization Method for Complex Time Green's Functions of Multilayer Media
Mohsen Ghaffari-Miab Amin Farmahini-Farahani Reza Faraji-Dana Caro Lucas
A new hybrid technique for optimization of a multivariable function is proposed. This method is applied to the problem of complex time Green's function of multilayer media. This technique combines Particle Swarm search algorithm with the gradient based quasi-Newton method. Superiority of the method is demonstrated by comparing its results with other optimization techniques.
AN EFFICIENT HYBRID SWARM INTELLIGENCE-GRADIENT OPTIMIZATION METHOD FOR COMPLEX TIME GREEN'S FUNCTIONS OF MULTILAYER MEDIA