Expanding the Bandwidth of Rectangular Microstrip Antenna by Inserting a Slot

In this work we were able to improve the reflection coefficient S11 and bandwidth BW of a rectangular microstrip antenna fed by a coaxial cable firstly by adjusting a the feed point and secondly by inserting a rectangular slot in the radiating element The results obtained using the HFSS software, have been compared by those published. These results are very satisfying

An improved neural network technique for data dimensionality reduction in satellite imagery

This paper presents an application of back-propagation neural network based mapping scheme of multispectrale data images. The approach exploits the ability of neural networks for non-linear projection of multidimensional data, and their advantages over traditional methods. An updating rule for this network, based on the Conjugate Gradient Algorithm is used. The main advantage of this algorithm is the speedup of the convergence rate. Performance evaluation using a Landsat image of Kénitra region (Morocco) is carried out. Classification results of the proposed algorithm outperform those obtained using conventional methods.Ce papier présente une nouvelle technique de réduction du nombre de canaux spectraux pour aider à la classification des images multispectrales en mode d'occupation du sol. Cette technique, basée sur des réseaux de neurones multicouches, propose une règle d'apprentissage de ces réseaux qui adapte le gradient conjugué à la méthode de rétropropagation; permettant ainsi une convergence rapide au réseau. Les résultats de classification sont évalués sur une fenêtre d'image Landsat-TM de 512*512 pixels, relative à la région de Kénitra (Maroc), et comparés à ceux obtenus par les méthodes classiques