1,721,103 research outputs found
SPOT-GPR analysis of ground penetrating radar signals recorded over the gneiss 14/20 region of the IFSTTAR geophysical test site: Preliminary results
No full textSPOT-GPR stands for 'Sub-array Processing Open Tool for GPR applications' and is a MATLAB-based software that can semi-automatically find and localize ('spot') targets in ground-penetrating radar (GPR) data. It implements a sub-array processing method, which combines smart-antenna and radar algorithms. In this paper, SPOT-GPR is used to analyse real GPR signals taken from the Open Database of Radargrams of COST Action TU1208. The considered data were recorded over the gneiss 14/20 region of a geophysical test site in Nantes, France, by using a pulsed radar system equipped with 900-MHz ground-coupled antennas. The acquisition line ran over nine steel and PVC pipes hidden in the gravel; the pipes were placed in different positions by the sloping side of the test site, mutually close enough to be strongly interfering. In previous studies, SPOT-GPR had been already tested on synthetic and real data; however, the data analysed in this paper were recorded over a more complex scenario than the previously-considered ones. The preliminary results presented herein show that SPOT-GPR is capable of detecting seven out of the nine targets buried in the test site, and their positions are estimated with variable accuracy. Since all radargrams included in TU1208 database are available for the scientific community, this case study has the added value to enable a comparison of the method implemented in SPOT-GPR with different detection algorithms that will be possibly tested on the same data by other authors in the future
Wire-grid electromagnetic modelling of metallic cylindrical objects with arbitrary section, for Ground Penetrating Radar applications
No full textA photonic-crystal selective filter
No full textA highly selective filter is designed, working at 1.55 μμm and having a 3-dB bandwidth narrower than 0.4 nm, as is required in Dense Wavelength Division Multiplexed systems. Different solutions are proposed, involving photonic crystals made rectangular- or circular-section dielectric rods, or else of holes drilled in a dielectric bulk. The polarization and frequency selective properties are achieved by introducing a defect in the periodic structure. The device is studied by using in-house codes implementing the full-wave Fourier Modal Method. Practical guidelines about advantages and limits of the investigated solutions are given
Design, Fabrication and Experimental Characterization of EBG Superstrates for Directivity Enhancement of Planar Antennas
No full textThree-dimensional Electromagnetic
Band-Gap (EBG) materials have been designed, by
using an in-house Fourier Modal Method (FMM)
code, to be employed as directivity-enhancing superstrates
for planar antennas. Alumina-woodpile
samples have been fabricated. Experimental results
have been collected, for the transmission properties
of EBG cavities, and comparisons have been performed
with FMM, with good agreement. The performances
of a woodpile-covered patch antenna have
been measured; the superstrate has been positioned
at different distances from the antenna and its orientation
has been varied; comparisons with the commercial
software HFSS show a good agreement. The
main effect of the EBG on the antenna performances
is an enhancement of about 10 dB in maximum gain
Algoritmi di stima di tipo sub-array processing per la localizzazione di conduttori cilindrici sepolti
No full text
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