Analysis and implementation of different topologies of transversal filters in planar technology

This paper uses a simple configuration to implement microwave transversal filters based on microstrip technology. The structure is of second order and implements two transmission zeros and two reflection zeros in the frequency response of the filter. The basic configuration consists of input and output ports coupled in a shunt configuration to two printed resonators of different lengths. A modification of the original structure is introduced to allow an additional direct coupling between the source and the load. Depending on the value and the sign of the coupling terms, different frequency responses can be obtained. In this way, small modifications in the basic structure allow to obtain band-pass or band-stop responses. Following this circuit topology, the paper discusses the possibilities to have transmission zeros in the real or in the complex plane and their effects on the frequency response and on the group delay of the filter. Also, two practical implementations in microstrip technology are proposed, and a third filter implementing group delay equalization is demonstrated. Measured results confirm theoretical predictions and validate the structures for practical applications.Ministerio de Educación y Ciencia, Ref. TEC2007-67630-C03-02. Fundación Séneca, Ref. 08833/PI/0

Analysis of Finite Microstrip Structures Using an Efficient Implementation of the Integral Equation Technique

An efficient numerical implementation of the Integral Equation technique (IE) has been developed for the analysis of the electrical characteristics of finite microstrip structures. The technique formulates a volume version of the IE for the finite dielectric objects, and a standard surface IE technique for the metallic areas. The system of integral equations formu- lated are solved with special numerical techniques described in this paper. The input impedances of several microstrip antennas have been computed, showing good agreement with respect mea- surements. The technique has shown to be accurate even for complex geometries containing several stacked dielectric layers. The radiation patterns of the structures have also been com- puted, and measured results from real manufactured hardware confirm that backside radiation and secondary lobes are accurately predicted by the theoretical model. The paper also discuss a suitable excitation model for finite size ground planes, and investigates the possibilities for an independent meshing of the metallic areas and the dielectric objects inside a given geom- etry. The practical value of the approach derived is that microstrip circuits can be designed minimizing the volume and size of the dielectric substrates.This work has been supported bythe Spanish National Project ESP2001-4546-PE, and RegionalSeneca Project PB/4/FS/02

Interactive Lab to Learn Radio Astronomy, Microwave & Antenna Engineering at the Technical University of Cartagena (Spain)

An initiative carried out at the Technical University of Cartagena (UPCT, Spain) to encourage students and promote the interest for Scientific and Engineering Culture between society is presented in this contribution. For this purpose, a long-term project based on the set-up of an interactive laboratory surrounding a small Radio Telescope (SRT) system has been carried out. The main novelty is that this project is entirely being developed by students of last courses of our Telecommunication Engineering Faculty, under the supervision of four lecturers. This lab offers the possibility to remotely control the SRT, and it provides a set of multimedia web-based applications to produce a novel, practical, multidisciplinary virtual laboratory to improve the learning and teaching processes in related sciences and technologies

Development of a Small Radio Telescope at the Technical University of Cartagena: A duty with our students and society

An initiative carried out at the Technical University of Cartagena (UPCT, Spain) to encourage students and promote the interest for Scientific and Engineering Culture between society is presented in this contribution. For this purpose, a medium-term (4 years) project based on the design, fabrication, testing and setup of a small Radio Telescope system has been carried out. The main novelty is that this project is entirely being done by students of last courses of our Telecommunication Engineering Faculty, under the supervision of four lecturers