Estudo e projeto de um filtro planar rejeita faixa sintonizável em estrutura metamaterial utilizando varactores.

Abstract

In present communication systems, tunable filters allow the circuits to work at several frequencies by adjusting the level of DC voltage. Beyond this functionality, others important factors in designing of the circuits, they are the degree of integration, low cost and small size. Aiming this necessity, a tunable band reject filters have proposed based on metamaterials structures in conjunction with diode varactors. This paper aims to present the study and design of this type of filter. Where, the use of structures metamaterials possible to obtain a filter with reduced size and the insertion of varactors become the filter tunable in frequency. A study of filters metamaterials (MTM) at Radiofrequency (RF) was done to determine the feasibility of using MTM in reject band filters. Then, three filters were designed and evaluated through simulations. After, measurements were performed on a system protected from electromagnetic interference (EMI). For this, we used: a stabilizer network, a signal generator, a tent shielded and a spectrum analyzer. The next step was to conduct a study to determine the possibility to become tunable filter by inserting varactors filters in the structures MTM. Four models have been proposed and analyzed using data obtained from simulations. Simulated and measured results are presented and discussed future improvements to the filter and the measurement procedures.