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2013-04-17
PIER
Vol. 138, 697-715, 2013
download: 159
A Planar Printed Antenna Array Embedded in the Wing Structure of a UAV for Communication Link Enhancement
Mohammad S. Sharawi Mohamed Ibrahim Sameir Deif Daniel N. Aloi
In this work a 12 element patch planar antenna array is designed, fabricated and tested along with its radio frequency (RF) feed network at 2.45 GHz. The array is designed to be embedded in the wing structure of a fixed wing hobby-type UAV. The planar array allows for beam steering with two degrees of freedom (θb,Φb). The maximum mutual coupling between antenna elements was -25 dB. The RF combiner was phase compensated to minimize the phase imbalance between its branches. The maximum measured antenna gain was 21.4 dB. The 3D Radiation pattern at several steering angles was measured at an outdoor antenna range facility. Measured and simulated values were in good agreement.
A PLANAR PRINTED ANTENNA ARRAY EMBEDDED IN THE WING STRUCTURE OF A UAV FOR COMMUNICATION LINK ENHANCEMENT
2013-04-17
PIER
Vol. 138, 675-696, 2013
download: 130
Time-Domain Real-Valued TM-Modal Waves in Lossy Waveguides
Oleg Tretyakov Mehmet Kaya
The waveguide has a perfectly conducting surface. Its cross section domain is bounded by a singly-connected contour of a rather arbitrary but enough smooth form. Possible waveguide losses are modeled by a homogeneous conductive medium in the waveguide. The boundary-value problem for the system of Maxwell's equations with time derivative is solved in the time domain. The real-valued solutions are obtained in Hilbert space L2 in a form of transverse-longitudinal decompositions. Every field component is a product of the vector element of the modal basis dependent on transverse coordinates, and the modal amplitudes dependent on time and the axial coordinate. Three examples are included. The dynamic properties of the modal waves and concomitant energetic waves are studied and their dependence on time illustrated graphically.
TIME-DOMAIN REAL-VALUED TM-MODAL WAVES IN LOSSY WAVEGUIDES
2013-04-14
PIER
Vol. 138, 661-673, 2013
download: 116
Multiband Handset Antenna Analysis Including LTE Band MIMO Service
Hyunho Wi Byeongkwan Kim Woojae Jung Byungje Lee
A compact multiband handset antenna including MIMO antenna operation for LTE 13 band (746~787 MHz) applications is proposed. The proposed antennas are separately located on the top and bottom portions of a mobile handset in order to use the antenna area more effectively. The proposed antenna achieves isolations of higher than 14 dB, enveloped correlation coefficients (ECC) of less than 0.25, and total efficiencies of greater than 40%. The operating frequency bands of Antenna 1 and Antenna 2 include the LTE 13 (746~787 MHz)/DCS/PCS/UMTS (1710~2170 MHz) bands and the LTE 13 (746~787 MHz)/GSM850/900 (824~960 MHz) bands, respectively.
MULTIBAND HANDSET ANTENNA ANALYSIS INCLUDING LTE BAND MIMO SERVICE
2013-04-14
PIER
Vol. 138, 647-660, 2013
download: 118
Far-Field Tunable Nano-Focusing Based on Metallic Slits Surrounded with Nonlinear-Variant Widths and Linear-Variant Depths of Circular Dielectric Grating
Pengfei Cao Lin Cheng Xiaoping Zhang Wei-Ping Lu Wei-Jie Kong Xue-Wu Liang
In this work, we present a new design of a tunable nanofocusing lens using a circular grating of linear-variant depths and nonlinear-variant widths. Constructive interference of cylindrical surface plasmon launched by the sub-wavelength metallic structure forms a sub-diffraction-limited focus, the focal length can be adjusted by varying the geometry of each groove in the circular grating. According to the numerical calculation, the range of focusing points shift is much more than other plasmonic lens, and the relative phase of emitting light scattered by surface plasmon coupling circular grating can be modulated by the nonlinear-variant width and linear-variant depth. The simulation result indicates that the different relative phase of emitting light lead to variant focal length. We firstly show a unique phenomenon for the linear-variant depths and nonlinear-variant widths of the circular grating that the positive change and negative change of the depths and widths of grooves can result in different of variation trend between relative phases and focal lengths. These results paved the road for utilizing the plasmonic lens in high-density optical storage, nanolithography, super-resolution optical microscopic imaging, optical trapping, and sensing.
FAR-FIELD TUNABLE NANO-FOCUSING BASED ON METALLIC SLITS SURROUNDED WITH NONLINEAR-VARIANT WIDTHS AND LINEAR-VARIANT DEPTHS OF CIRCULAR DIELECTRIC GRATING
2013-04-14
PIER
Vol. 138, 629-645, 2013
download: 140
A Dual-Frequency Method of Eliminating Liquid Water Radiation to Remotely Sense Cloudy Atmosphere by Ground-Based Microwave Radiometer
Jiangman Li Li-Xin Guo Le-Ke Lin Yiyang Zhao Zhenwei Zhao Tingting Shu Hengmin Han
Ground-based microwave radiometer is the main device to remotely sense atmosphere passively which can detect the water vapor density, temperature, integral water vapor, etc. Because of the influence of liquid water in cloud on the brightness temperature measured by microwave radiometer, the cloud needs to be modeled to retrieve the parameters of atmosphere. However, the difference between cloud model and actual cloud may bring on error in retrieval. Based on the relation between absorption coefficient of liquid water and frequency, a dual-frequency method of eliminating liquid water radiation which is not based on modeling cloud is put forward to retrieve the parameters of cloudy atmosphere. Historical radiosonde data are employed in the calculation of retrieval coefficients to profile the water vapor. The simulation and experiment results show that the dual-frequency method can eliminate the affection of liquid water effectively. So the error in modeling cloud can be avoided to improve the retrieval precision. The integral water vapor in cloudy atmosphere is also retrieved by the dual-frequency method, and the precision is almost the same with the method of modeling cloud.
A DUAL-FREQUENCY METHOD OF ELIMINATING LIQUID WATER RADIATION TO REMOTELY SENSE CLOUDY ATMOSPHERE BY GROUND-BASED MICROWAVE RADIOMETER
2013-04-12
PIER
Vol. 138, 613-627, 2013
download: 171
A Novel 2.45 GHz Switchable Beam Textile Antenna (Sbta) for Outdoor Wireless Body Area Network (WBAN) Applications
Mohd Ilman Jais Mohd Faizal Bin Jamlos Muzammil Jusoh Thennarasan Sabapathy Muhammad Ramlee Kamarudin Raad Badlishah Ahmad Azremi Abdullah Al-Hadi Emi Izhanizam Bin Azmi Ping Jack Soh Guy Vandenbosch Nur Laila Ishak
A novel switchable beam textile antenna (SBTA) for wireless body area network (WBAN) applications is proposed. The SBTA is centrally-fed by a coaxial probe and the power distributed over four circular radiating elements. Four RF switches are integrated through which the SBTA is able to generate beam steering in four directions: 0°, 90°, 180°, and 270°, with a maximum directivity of 6.8 dBi at 0°. Its small size (88 mm x 88 mm) and flexibility enables the structure to be easily integrated into safety jackets, rain coats, etc., for tracking, and search and rescue communication purposes. The structure successfully integrates reconfigurability into a wearable textile antenna.
A NOVEL 2.45 GHz SWITCHABLE BEAM TEXTILE ANTENNA (SBTA) FOR OUTDOOR WIRELESS BODY AREA NETWORK (WBAN) APPLICATIONS
2013-04-11
PIER
Vol. 138, 599-611, 2013
download: 112
The Fine-Grained Parallel Micro-Genetic Algorithm and Its Application to Broadband Conical Corrugated-Horn Antenna
Lei Chang Haijing Zhou Ling-Lu Chen Xiang-Zheng Xiong Cheng Liao
The fine-grained parallel micro-genetic algorithm (FGPMGA) is developed to solve antenna design problems. The synthesis of uniformly exited unequally spaced array is presented. Comparison with the micro-genetic algorithm (MGA) has been carried out. It is seen that the FGPMGA significantly outperforms MGA, in terms of both the convergence rate and exploration ability. The FGPMGA can also reduce the optimization time. Then the FGPMGA and the body of revolution finite-difference time-domain (BOR-FDTD) are combined to achieve an automated design process for conical corrugated-horn antenna. Numerical simulation results show that the horn antenna has good impedance matching (the VSWR is less than 1.5), stable beamwidth and gain, as well as good rotation symmetry patterns over the whole band 8~13 GHz.
THE FINE-GRAINED PARALLEL MICRO-GENETIC ALGORITHM AND ITS APPLICATION TO BROADBAND CONICAL CORRUGATED-HORN ANTENNA
2013-04-11
PIER
Vol. 138, 585-598, 2013
download: 111
Design of a Compact Quad-Band Hybrid Antenna for Compass/WiMAX /WLAN Applications
Panlin Shu Quanyuan Feng
A compact quad-band hybrid antenna for Compass/WiMAX/WLAN applications is proposed. The hybrid antenna is designed based on the method of combining a composite right/left-handed transmission line (CRLH-TL) unit cell with a meandered monopole and wide multi-band characteristics are achieved by merging some of resonance frequencies of the CRLH-TL unit cell and meandered monopole together. Coplanar waveguide (CPW) is used as a parallel excitation for both the CRLH-TL unit cell and meandered monopole. A prototype of the proposed hybrid antenna has been constructed and experimentally studied. The measured results show that four distinct operating bandwidths with 10 dB return loss are about 30 MHz (1.25-1.28 GHz), 290 MHz (2.44-2.73 GHz), 650 MHz (3.17-3.82 GHz) and 1130 MHz (5.03-6.16 GHz), covering the Compass B3, 2.5/3.5/5.5 GHz WiMAX and 5.2/5.8 GHz WLAN bands. Furthermore, the antenna has a single-layer planar structure with a small volume of only 31 × 21 × 2 mm3. Acceptable radiation patterns and peak realized gains are obtained over the operating bands.
DESIGN OF A COMPACT QUAD-BAND HYBRID ANTENNA FOR COMPASS/WIMAX/WLAN APPLICATIONS
2013-04-04
PIER
Vol. 138, 571-584, 2013
download: 112
Fringe Waves in an Impedance Half-Plane
Husnu Deniz Basdemir
The uniform expressions of scalar fringe waves which are based on the physical theory of diffraction (PTD) were obtained for the impedance half plane in terms of the Fresnel integrals. Asymptotic and uniform forms of the fringe fields were compared. The radiated fields of the fringe expressions were analyzed numerically.
FRINGE WAVES IN AN IMPEDANCE HALF-PLANE
2013-04-04
PIER
Vol. 138, 555-569, 2013
download: 172
An Extended Inverse Chirp-Z Transform Algorithm to Process High Squint SAR Data
Yue Liu Yun-Kai Deng Robert Wang
This paper proposes an Extended Inverse Chirp-Z Transform (EICZT) algorithm to handle the high squint FMCW SAR data, where the conventional Inverse Chirp-Z Transform (ICZT) cannot work due to the failure in dealing with the range-variance of second- and higher-order range-azimuth coupling terms. A pre-processing operation is implemented in the azimuth-Doppler and range-time (Doppler-time) domain, where a perturbation function consisting of second-order and third-order range time variables is implemented to compensate the range variance of the second order range terms. Moreover, a new scaling factor is formulated to represent the Range Cell Migration (RCM), and further corrected by the presented EICZT approach. The proposed approach is analyzed and compared with the conventional ICZT. The simulated high squint SAR scene with nine targets is well focused by the proposed approach and the quality is greatly improved with respect the conventional ICZT. The proposed algorithm is also validated by the X-band high-resolution real SAR data.
AN EXTENDED INVERSE CHIRP-Z TRANSFORM ALGORITHM TO PROCESS HIGH SQUINT SAR DATA
2013-04-04
PIER
Vol. 138, 537-553, 2013
download: 209
A Physical Optics Approach to the Analysis of Large Frequency Selective Radomes
Ugo d'Elia Giuseppe Pelosi Christian Pichot Stefano Selleri Massimo Zoppi
State-of-the-art radomes exploit frequency selective media so as to be transparent for the frequencies of the antenna protected by them and opaque to other frequencies. This feature helps in reducing the radar cross section of the antenna and in protecting it from interference. The study of a frequency selective radome is a daunting task, since the radome is usually large in terms of wavelengths, hence full wave analyses are prohibitive. In this paper an approximate technique, based on the physical optics concept, is proposed to attain an estimation of the behavior of a radome shielded antenna in a short time with a commonly available computer. Results are validated against a full wave technique over a relatively small radome.
A PHYSICAL OPTICS APPROACH TO THE ANALYSIS OF LARGE FREQUENCY SELECTIVE RADOMES
2013-04-03
PIER
Vol. 138, 519-536, 2013
download: 104
Comparison of the Two-Scale and Three-Scale Models for Bistatic Electromagnetic Scattering from Ocean Surfaces
Hejia Luo Yang Du
With rapid development of satellite technology in monitoring the ocean, a good understanding of the physical processes involved in the electromagnetic ocean-surface interaction is required. The composite surface models are usually applied in the analysis of the interaction, hence a systematical check of their region of validity is desirable. Based on a generalized minimal residual procedure which is right preconditioned (GMRES-RP) that we have recently developed which has demonstrated the desirable properties of a numerical algorithm: robust and efficient, in this paper, for bistatic scattering from one dimensional ocean surfaces, we carry out a systematic assessment of the performance of the popular two-scale model and the advanced three-scale model under different conditions of ocean surface wind speeds, polarizations, frequencies, and incidence angles. It is found that the two-scale model in general captures the bistatic scattering pattern, yet the accuracy of geometrical optics (GO) for the large scale wave brings considerable impact on the overall accuracy. If the evaluation of the contribution of the large scale wave is instead using direct numerical integration for the corresponding Kirchhoff integral, impressive improvements are frequently observed, especially at low frequency (L and C bands) and low wind speed (3 m/s). But care should be taken when apply two-scale method with numerical integration, since there are cases where visible discrepancy with method of moment (MoM) are observed. On the other hand, the three-scale model is found in very good agreement with MoM across the considered ocean surface wind speeds, polarizations, frequencies, and incidence angles, hence represents a much advanced model over the two-scale model.
COMPARISON OF THE TWO-SCALE AND THREE-SCALE MODELS FOR BISTATIC ELECTROMAGNETIC SCATTERING FROM OCEAN SURFACES
2013-04-03
PIER
Vol. 138, 499-518, 2013
download: 125
Effective Reconstruction of the Rotation-Induced Micro-Doppler from a Noise-Corrupted Signature
Ji-Hoon Park Noh-Hoon Myung
This paper presents an effective method for reconstructing the rotation-induced micro-Doppler (m-D) from a signature corrupted by noise. An adaptive low-pass filter is employed as a preprocessor of empirical mode decomposition (EMD) in order to effectively extract the first chopping harmonic component of the rotation-induced m-D. Then the extracted component is used for reconstructing the original m-D signature in the joint time-frequency domain. Although it is difficult to interpret the time-frequency representation of the noise-corrupted signature, the reconstruction of the m-D enables the acquisition of related information and can be used for complementing other traditional analysis methods. By validating the applicability of the proposed method with measured jet engine modulation (JEM) signatures, we demonstrate that the reconstruction process presented in this paper is expected to be significantly helpful for radar target recongnition in real environments.
EFFECTIVE RECONSTRUCTION OF THE ROTATION-INDUCED MICRO-DOPPLER FROM A NOISE-CORRUPTED SIGNATURE
2013-04-01
PIER
Vol. 138, 479-497, 2013
download: 138
Statistical Characteristics of the Multi-Path Time Delay and Doppler Shift of a Radar Wave Propagating through the Ionosphere
Bao-Ke Ma Li-Xin Guo Hongtao Su
Multi-path time delay spread is a very important factor in the bit error rate of high-frequency ionospheric communication channels and in the target detection performance of over-the-horizon radars. In this study, the probability density distribution of multi-path time delay and Doppler shift of ionospheric radio signal are derived using Rayleigh fading. Moreover, the probability density distribution of time delay, average power of the received signal, and received signal variance are discussed in detail. Using a designed experimental circuit, the measured value of the multi-path time delay spread is obtained from three given radio paths by the sweep-frequency pulse sounding technique. The average value of the multi-path time delay spread that changes with the ratio K, which is the operating frequency of the basic maximum usable frequency, is also analyzed and fitted using the least-squares fitting method. Theoretical and statistical research shows that for a given radio path and specific frequency, the multi-path time delay spread approximately follows a normal distribution. The average time delay spread decreases with the increase in the ratio K; however, it eventually approaches a steady value. The results of this research provide an empirical reference for further prediction and estimation of the time delay spread of a radar wave propagating through the ionosphere.
STATISTICAL CHARACTERISTICS OF THE MULTI-PATH TIME DELAY AND DOPPLER SHIFT OF A RADAR WAVE PROPAGATING THROUGH THE IONOSPHERE
2013-03-30
PIER
Vol. 138, 467-478, 2013
download: 108
B -Calm: an Open-Source Multi-GPU-Based 3D-FDTD with Multi-Pole Dispersion for Plasmonics
Pierre Wahl Dany Sebastien Ly Gagnon Christof Debaes Jurgen Van Erps Nathalie Vermeulen David A. B. Miller Hugo Thienpont
Numerical calculations based on finite-difference timedomain (FDTD) simulations for metallic nanostructures in a broad optical spectrum require an accurate modeling of the permittivity of dispersive materials. In this paper, we present the algorithms behind BCALM (Belgium-CAlifornia Light Machine), an open-source 3D-FDTD solver simultaneously operating on multiple Graphical Processing Units (GPUs) and efficiently utilizing multi-pole dispersion models while hiding latency in inter-GPU memory transfers. Our architecture shows a reduction in computing times for multi-pole dispersion models and an almost linear speed-up with respect to the amount of used GPUs. We benchmark B-CALM by computing the absorption efficiency of a metallic nanosphere in a broad spectral range with a six-pole Lorentz model and compare it with Mie theory and with a widely used Central Processing Unit (CPU)-based FDTD simulator.
B-CALM: AN OPEN-SOURCE MULTI-GPU-BASED 3D-FDTD WITH MULTI-POLE DISPERSION FOR PLASMONICS
2013-03-30
PIER
Vol. 138, 453-466, 2013
download: 109
Investigation of Quasi-Optical Bessel-Gauss Resonator at mm - and Submm-Wavelengths
Yan-Zhong Yu Wen-Bin Dou
A research of a quasi-optical Bessel-Gauss resonator (QOBGR) at millimeter (MM) and submillimeter (SubMM) wavebands is presented in this paper. The design is based on the quasi-optical theory and technique. The iterative Stratton-Chu formula (ISCF) algorithm is employed to analyze the output characteristics of the cavity, including the resonant modes, phases, power losses and phase shifts. Analysis of the results demonstrates that the present design of the QOBGR can support zero order or any high order mode of the pseudo Bessel-Gauss beam. At the output plane the intensity distributions of these modes are modulated by a Gauss-shaped envelope, and their phase patterns have an approximate block-like profile. Tolerance analysis for the designed QOBGR is also done. Lastly, a comparison of resonating modes is made between QOBR (quasi-optical Bessel resonator) and QOBGR when both are configured with the same geometric parameters.
INVESTIGATION OF QUASI-OPTICAL BESSEL-GAUSS RESONATOR AT MM- AND SUBMM-WAVELENGTHS
2013-03-29
PIER
Vol. 138, 433-451, 2013
download: 102
Compressed Sensing Based Track Before Detect Algorithm for Airborne Radars
Jing Liu Chong Zhao Han Xiang Hua Yao Feng Lian
This paper presents a novel compressed sensing based track before detect (CS-TBD) algorithm. The proposed algorithm reconstructs the whole radar scenario (direction of arrival (DOA)-Doppler plane) for each range gate at consecutive scans using an improved stagewise orthogonal matching pursuit (StOMP) algorithm, resulting in a three-dimensional range-DOA-Doppler space. It then performs temporal tracking in the newly built three-dimensional range-DOA-Doppler space, based on the information from multiple illuminations during each scan, as well as among consecutive scans. In the proposed CS-TBD algorithm, the improved StOMP algorithm together with the temporal tracking, can effectively distinguish true targets from false targets and clutter based on information from multiple illuminations.
COMPRESSED SENSING BASED TRACK BEFORE DETECT ALGORITHM FOR AIRBORNE RADARS
2013-03-28
PIER
Vol. 138, 421-432, 2013
download: 184
Giant Circular Dichroism and Negative Refractive Index of Chiral Metamaterial Based on Split-Ring Resonators
Yongzhi Cheng Yan Nie Lin Wu Rong Zhou Gong
In this paper, a double-layer split-ring resonator structure chiral metamaterial was proposed which could exhibit pronounced circular dichroism (CD) effect and negative refractive index at microwave frequencies. Experiment and simulation calculations are in good agreement. The retrieved effective electromagnetic parameters indicate that the lower frequency CD effect is associated with the negative refractive index property of the left circularly polarized (LCP) wave, and the upper one is to the right circularly polarized (RCP) wave. The mechanism of the giant CD effect could be further illustrated by simulated surface current and power loss density distributions.
GIANT CIRCULAR DICHROISM AND NEGATIVE REFRACTIVE INDEX OF CHIRAL METAMATERIAL BASED ON SPLIT-RING RESONATORS
2013-03-28
PIER
Vol. 138, 407-419, 2013
download: 124
Terahertz Sensing Application by Using Fractal Geometries of Split-Ring Resonators
Yanbing Ma Huai-Wu Zhang Yuanxun Li Yicheng Wang Weien Lai
In this study, we report the simulation, fabrication and characterization of a dual-band fractal metamaterial used for terahertz sensing application. By applying the fractal structures of square Sierpinski (SS) curve to the split-ring resonators (SRRs), more compact size and higher sensitivity can be achieved as privileges over conventional SRRs. The influence of different geometrical parameters and the order of the fractal curve on the performances are investigated. Then overlayers are added to the fractal SRRs in order to explore the performance of the entire system in terms of sensing phenomenon. The changes in the transmission resonances are monitored upon variation of the overlayer thickness and permittivity. Measured results show good agreement with simulated data. At the second resonance of the second-order SS-SRRs, maximum frequency shifts of 19.8 GHz, 26.3 GHz and 37.8 GHz were observed for a 2 μm, 4 μm and 10 μm thickness of photoresist. The results show good sensitivity of the sensors suggesting they can be used for a myriad of terahertz sensing applications in biology and chemistry.
TERAHERTZ SENSING APPLICATION BY USING FRACTAL GEOMETRIES OF SPLIT-RING RESONATORS
2013-03-28
PIER
Vol. 138, 389-405, 2013
download: 152
Five-Zone Propagation Model for Large-Size Vehicles Inside Tunnels
Ke Guan Zhangdui Zhong Bo Ai Ruisi He Cesar Briso-Rodriguez
An accurate characterization of the wave propagation inside tunnels is of practical importance for the design of advanced communication systems. This paper presents a five-zone propagation model for large-size vehicles inside tunnels. Compared with existing models, the proposed model considers the influence of the large size of the vehicle, and covers all propagation mechanism zones and their dividing points. When a large-size vehicle is passing the transmitter, the received power suffers a deep fading as the direct wave is blocked by the vehicle itself. This zone is called the near shadowing zone. Then, when the vehicle has moved past the transmitter, the line of sight is recovered. If the vehicle is still close to the transmitter, the free space propagation zone starts. Then, as the distance increases, the vehicle enters the multi-mode propagation zone, where higher order modes are significant. Further away, when high order modes are greatly attenuated, guided propagation is stabilized. Finally, when the vehicle is extremely far from the transmitter, the waveguide effect vanishes because of the attenuation of reflected rays. Two sets of measurements are employed to validate the model. Results show good agreement, and therefore, the model presents an effective way to predict the propagation inside tunnels for large-size vehicles.
FIVE-ZONE PROPAGATION MODEL FOR LARGE-SIZE VEHICLES INSIDE TUNNELS