Papers by Cesar Rodriguez
IEEE Transactions on Vehicular Technology, 2007
This paper covers some of the work carried out in the planning of the Global System for Mobile Co... more This paper covers some of the work carried out in the planning of the Global System for Mobile Communication for Railway (GSM-R) of the tunnels on the new high-speed trains in Spain. Solutions based on distributed antenna systems have been tested by installing several 900-MHz transmitters inside and outside of a 4000-m tunnel and measuring the propagation in different conditions. The measurements have been used to model the effects of tunnel propagation, including curves, trains passing from the outside to the inside, and the effect of two trains passing inside the tunnel. All cases have been tested by comparing solutions using isofrequency and multifrequency distributed transmitters inside the tunnel. The improvements of signal-to-noise ratio and the reduction of the blocking effects of two trains passing have demonstrated the advantages of using isofrequency distributed antenna systems in tunnels. Finally, a complete propagation model combining both modal analysis and ray tracing has been applied to predict the propagation loss inside and outside these tunnels, and results have been compared with the measurements. The model has proven to be very useful for radio planning in new railway networks.
IEEE Transactions on Microwave Theory and Techniques, 2005
A new combline filter structure with a continuous tunability for both the center frequency and ba... more A new combline filter structure with a continuous tunability for both the center frequency and bandwidth is presented in this paper. The passband-width tunability is achieved by placing variable coupling reducers between the filter resonators. The coupling reducers, operating as bandwidth control subnetworks, are designed as detuned resonators made up of a line segment ending in a variable capacitor. The proposed filter structure is experimentally validated with the design, construction in suspended stripline technology, and characterization of a low-cost filter prototype for terrestrial digital video broadcasting receivers operating in the UHF band (470-862 MHz). Other relevant factors, such as the intermodulation distortion produced by the varactors used to control the bandwidth electronically or the power-handling performance of the constructed filter, are also discussed. The reconfigurable filter module described in this paper is very suitable for the design of flexible multifunction receiver subsystems simultaneously supporting signals with a different bandwidth.
Se presenta una revisión de la morfología estructural y funcional de la Articulación temporomandi... more Se presenta una revisión de la morfología estructural y funcional de la Articulación temporomandibular (ATM), las relaciones entre las articulaciones derecha e izquierda, sus ligamentos, su disco articular y sus movimientos y se hace un acercamiento a la clínica y la patología de esta articulación.
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Papers by Cesar Rodriguez