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This paper presents the feasibility study of the beam-waveguide (BWG) system of the third deep-space antenna of ESA (DSA3), which is planned to be built in the Americas. The main challenge of this design consists in combining the X band (7.145-8.5 GHz) and the Ka band downlink channel (31.8-32.3 GHz), already operating in the existing DSA2, with the new receiving band, namely the K band, ranging from...
A novel strategy has been presented to design multi-beam reflector antenna system based on the excitation of a couple of leaky waves by covering the focal plane array with a single thin dielectric layer and tuning the array design to maximize their positive effect. In the worst case scenario of neighboring co-frequency and co-polarized beams an increase of the Geoc of 1 dB over a 6% BW with respect...
The design strategy that uses dielectric super-layers with neighboring wave-guides closed in matched loads constitutes a worst case scenario as far as the performance enhancement is concerned and finds applicability in radiometric imaging arrays. On the other side the design strategy that uses dielectric super-layers with neighboring wave-guides closed in properly tuned reactive loads can be seen...
The objective of this paper is to present a formulation for the Inverse Scattering Problem [1] based on the expansion of the equivalent currents by using the Rao-Wilton-Glisson (RWG) basis functions [2]. The purpose is to reconstruct the sources from measured near-field data. The goal is to improve the resolution for the equivalent sources characterization, by avoiding the currents discontinuity along...
In this paper, we develop a hybrid PSTD-FDTD method combining the discontinuous galerkin PSTD (DG-PSTD) method (Q.H.Liu and G.Zhao) with the CFDTD method and the ADI-CFDTD(M.Chai,et al) method for the mixed-scale problem. We apply the newly developed hybrid PSTD-FDTD method to wireless communication systems to capture both the wireless RF components property and wave propagation in an indoor wireless...
The European School of Antennas (ESoA) is a new model of geographically distributed school that has the objective to reinforce the European training and research in antennas and relevant applications.
Informal and formal assessments combined with course evaluations indicated that the learner-centered activities described above met their intended objectives. Collectively, these activities improved students' conceptual understanding, promoted active and cooperative learning, and inspired students to pursue personal interests relating to electromagnetics.
This paper presents a useful educational tool, EZ-Scattering, which help to illustrate phenomenon of the electromagnetic scattering from arbitrary two- dimensional structures. EZ-Scattering calculates the radar cross section and induced surface currents for different two-dimensional shapes that user draws using generic drawing software. The approach presented here is intended to develop a self-paced...
Communication skills are an essential part of engineering education in order to prepare students to be competent for engineering industry. This paper described a project-based learning activity that integrated communication through lab reports to improve students' higher level engineering skills and increase their communication skills. By guiding students to answer questions about observations and...
The Remote Educational Antenna Laboratory is a new facility for the purpose of providing calibrated characterization of student constructed antennas. When completely operational, it will be available for use by students and instructors around the world, providing measurement experience to enhance and deepen the practical understanding of antennas.
Modern electronic systems engineering requires understanding of several core topics that include circuit analysis, signal processing, digital/analog electronics, and electromagnetic fields. In fact, the latter subject has gained a renewed significance in engineering education, as electronic systems become more integrated, operate at higher frequencies and switch with faster speeds. Compact electronic...
We are investigating techniques that electrically change the conductivity of microstrip patch antennas. Altering the conductivity of certain areas of a patch antenna can be useful for controlling the weighting of elements in an array or for tuning the antenna to a desirable frequency. Materials that have adjustable conductivity include conductive electoactive polymers and silicon. Conductive electoactive...
Dual-reflector antennas have been investigated for omnidirectional coverage, where the reflector surfaces are bodies of revolution obtained by spinning confocal conic sections or shaped generating curves about a common symmetry axis. The aim of this work is to complement the previous investigations by deriving the GO aperture held of omnidirectional axis-displaced dual-reflector antennas with an arbitrary...
Today's satellite communication systems operate mainly in C and Ku frequency bands. They are characterized by broad regional coverages, relatively low satellite gain, EIRP and G/T, and modest data rates. Multibeam payloads and frequency re-use, associated to large bandwidth are the concepts that actual generation communication systems use to palliate these shortcomings.
Calibration is the process of constructing a mathematical model to relate the output of an instrument to properties of samples. Prediction is the process of using the model to predict properties of a sample given and instrument output. A statistical description, based on discriminant analysis, of explosive substances allows a characterization and classification of the spectroscopic properties of the...
Femtosecond laser-induced breakdown spectroscopy (LIBS) has been shown to be effective in detecting TNT, RDX, and other explosive related compounds. We chose to focus on aluminum and glass substrates since these allowed us to study the effects of strong linear absorption for a metal and the multiphoton absorption for a dielectric. For the FLMS experiments only stainless steel substrates were used.
The paper gives an overview on the different aspects in signal generation for reflective THz time domain spectroscopy. It is also demonstrated that the trace signature can be recovered even from a rough, inhomogeneous surface, and introduce models which can describe a number of substrate geometries. A thorough understanding of signal generation in THz time domain spectroscopy is the foundation for...
In this paper we describe the recent results from an ongoing project at the University of Hawaii to use advanced GPR technology for the detection and discrimination of UXO in the high iron content volcanic soil of Hawaii. To help determine a suitable frequency range for detecting targets at two feet depth from the surface, a soil characterization effort has been implemented. Both the dielectric and...
For reflection spectroscopy in particular, the measured response from an explosive material may be dominated by rough surface scattering, which is in turn influenced by a number of factors including: the size and density of explosive grains and air voids, the dielectric contrast, the angle of incidence and scattering, and the operating frequency. In this paper, scattering from a granular explosive...
A folded metal boxed dipole is of considerable interest as a broadband antenna element, and has good potential for use in low cost base station antenna design for wireless communications. In this paper, experimental and simulation results are presented which include both a folded metal single dipole, and a dual polarized boxed dipole. The results show that this new dipole element has excellent gain...
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