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This paper proposes a new method for computing the spectrum of a periodic analog signal, based on the concept of minimizing a square error function. The method involves generating the error function, which is accomplished using symbolic computation with the program Maple, and the minimization of this function using the genetic algorithms and gradient methods using the program Matlab.
This paper presents a synthesis approach based on a variable slope profile. The method is demonstrated by synthesizing an antenna with a quasi-constant gain over a given frequency range. The antenna configuration resulting from synthesis was simulated, manufactured and measured in order to validate our method.
We have previously proposed an indoor measuring technique for antenna gain, based on averaging a normalized transfer function over a distance range. Simulated and measured results have also been presented, in order to validate the method. In this paper, we assess the accuracy of our method by comparing the results to those issued from a traditional, non-anechoic approach, i.e., the time-gating method,...
Antenna gain is generally measured either in an anechoic chamber or in an open test site. In this paper, we propose an indoor measuring technique based on averaging the magnitude of a normalized transfer function over a distance range. The effects of reflection and diffraction on the mean normalized transfer function are firstly investigated, prior to find the impact of the distance range on the measuring...
Low-distortion antennas for pulsed excitation can be synthesized by using a technique based on a finite expansion of the antenna time-domain response. Current profiles can therefore be generated in order to achieve optimal response for a given waveform of excitation. However, the simplest radiating structures resulting from synthesis might neither provide acceptable input matching, nor omnidirectional...
a We consider a neutrino large-scale radio Cherenkov observatory in a Romanian salt mine. We include propagation effects on the radio signal generated and make a threshold analysis, taking into account how the pulse couples to a realistic receiver and signal-to-noise ratio limiting situations.
This paper investigates the behavior of a CDMA system in conditions of underground propagation collaborated with QPSK modulated signals. The antennas contained in boreholes were modeled as transmission lines. We studied the influence of the impurities of the propagation medium and also presented the role of the dimensions of the drilled cavity that the antennas are contained in. We also investigated...
We are investigating the possibility to construct a radio Askaryan neutrino observatory in a salt mine. The first step is to determine the optimal geometry such that the cost of experiment remains small but detection is still possible. For that we analyze the characteristics of the radio signal on its propagation from the site of the shower to a point where it intersects the radio antenna. We make...
Recent trends in computer graphics has lead to a spectacular grow of the amount of complex 3D objects stored and exchanged over the Internet. In this context accurate mesh decimations schemes are becoming more and more urgent due to the rendering speed reason and fast transmission. In this paper we present a complete evaluation of the mesh simplification techniques existing in the technical literature...
In this paper we introduce an enhanced graph partition model, more robust, used for video sequences temporal segmentation. In the first part we examine the formal framework of the shot boundary detection techniques implemented in the recent years, emphasizing the weakness and strength for each method. In the second phase we present our novel algorithm that applies a scale space median filtering on...
We are investigating the possibility to reconstruct the energy and direction of cosmic neutrinos from the measured voltage of the radio signals emitted. The detector based on the Askaryan effect is built in salt so all propagation effects that affect the characteristics of the generated radio signal should be characterized. Measurements are also influenced by the properties of antenna so its behavior...
A new topology for fourth-order microstrip bandpass filters is investigated in this paper. Compared to the classical quadruplet, the proposed new topology offers an extra coupling between two resonators, allowing this way the design of fourth order filters with two attenuation poles situated on the same side of the passband. A strongly asymmetric transfer characteristic can be obtained by a proper...
The area of underground radio technology represents a constant problem among radio communication systems. This paper aims to suggest a possible scenario for transmission/receiving of signals from a salt mine. It is assumed that the system used is a synchronous CDMA system and the users' signals have equal powers. In order for the performances to be improved the simulation includes digital modulation...
A new dual band rat-race coupler with left handed transmission lines is presented in this paper. The main advantage of this novel coupler is that there are used a reduced number of cells, meanwhile the performances improve. In order to reduce the dimensions of the coupler, the 3λ/4 CRLH transmission line has been replaced with a D-CRLH transmission line, and moreover there have been introduced a new...
A new asymmetric backward coupler is obtained by edge-coupling two types of composite right/left handed (CRLH) lines. This novel coupler is analyzed in a microwave range (1-10 GHz) and the magnitude of the scattering parameters reveals tight coupling effects (even 0 dB) in a dual frequency band and also very good directivity in the working band.
This article presents a comparison between different simulated exposure scenarios of the human female complex urinary and reproductive systems to nonionizing electromagnetic radiation. Numerical simulations were run using commercial software based on the finite difference time domain method. The frequency of the electromagnetic radiation was changed alternatively between four values: 2.5 GHz, 3.5...
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