Current Issue : January - March Volume : 2014 Issue Number : 1 Articles : 6 Articles
Effective diagnostics with ground penetrating radar (GPR) is strongly dependent on the amount and quality of available data as well\r\nas on the efficiency of the adopted imaging procedure. In this frame, the aim of the present work is to investigate the capability of a\r\ntypical GPR system placed at a ground interface to derive three-dimensional (3D) information on the features of buried dielectric\r\ntargets (location, dimension, and shape). The scatterers can have size comparable to the resolution limits and can be placed in\r\nthe shallow subsurface in the antenna near field. Referring to canonical multimonostatic configurations, the forward scattering\r\nproblem is analyzed first, obtaining a variety of synthetic GPR traces and radargrams by means of a customized implementation of\r\nan electromagnetic CAD tool. By employing these numerical data, a full 3D frequency-domain microwave tomographic approach,\r\nspecifically designed for the inversion problem at hand, is applied to tackle the imaging process. The method is tested here by\r\nconsidering various scatterers, with different shapes and dielectric contrasts.Theselected tomographic results illustrate the aptitude\r\nof the proposed approach to recover the fundamental features of the targets even with critical GPR settings....
A novel compact and circular polarized antenna is proposed which can be easily fabricated and embedded into RFID readers.\r\nCircular polarization characteristic of the proposed antenna is achieved by introducing a crossed branch.Themodified meandering\r\nline structure gives the antenna compactness characteristic. A prototype is fabricated and measured. The results show that this\r\ncircular polarized antenna with compact dimension can cover the Chinese RFID operating band from920MHz to 925MHz, which\r\nmake�s the antenna suitable for handheld terminal application of RFID readers....
This paper presents software based design, analysis and development of dual frequency circular microstrip patch antenna for a C-band applications. Different types of slots are etched in the circular patch to provide dual frequency operation. In all designs the circular patch is mounted on RT/Duriod 5880 glass microfiber reinforced PTFE composite substrate material. The designs are simulated and analyzed by Finite Element Method (FEM) based High Frequency Structure Simulator (HFSS™ EM simulator software). The antenna is designed to operate in C band with dual frequency response. Return loss (S11), Voltage Standing Wave Ratio (VSWR), Radiation Patterns (E-plane and H-plane) plots are presented for all designed antennas. Results of proposed antenna structure shows good return loss, VSWR (<2) and gain as depicted in graphs. One of the designs is fabricated. Measurement of fabricated antenna is performed....
A new approach is proposed to detect scatterers embedded in reciprocal media from scattering data.The new method is rooted on\r\nphysical considerations, in particular, on the optical theorem applicable to wavefields (e.g., acoustic, electromagnetic, and optical).\r\nThe approach exploits insight gained fromthe optical theoremwhich assigns physical energy interpretations to the wave data from\r\ntime reversal mirrors and cavities fromwhich one can deduce the presence of unknown scatterers in unknown background media.\r\nTheproposed approach is ideally suited for target detection in complex, highly reverberating unknown environments such as indoor\r\nfacilities, caves, tunnels, and urban canyon....
This paper considers a 2-user multiple-input single-output (MISO) interference channel with confidential messages (IFC-CM),\r\nin which the Rician channel model is assumed. The coordinated beamforming vectors at the two transmitters have the similar\r\nparameterizations as those for perfect CSI, which could be optimized jointly and achieved by agreeing on the real parameters\r\nbetween the two users. Our main contribution is that a quadratic relationship between the two real-valued parameters can be\r\nderived for the Rician channel to reach the ergodic secrecy rate balancing point. Simulation results present the secrecy performance\r\nover the 2-user MISO IFC-CM scenario....
We propose a three-dimensional microwave holographic imaging method based on the forward-scattered waves only. In the\r\nproposed method, one transmitter and multiple receivers perform together a two-dimensional scan on two planar apertures on\r\nopposite sides of the inspected domain. The ability to achieve three-dimensional imaging without back-scattered waves enables the\r\nimaging of high-loss objects, for example, tissues, where the back-scattered waves may not be available due to low signal-to-noise\r\nratio or nonreciprocalmeasurement setup.The simulation and experimental results demonstrate the satisfactory performance of the\r\nproposed method in providing three-dimensional images. Resolution limits are derived and confirmed with simulation examples....
Loading....