Utilização de substratos heterogêneos e planos de terra inclinados no desenvolvimento de antenas e filtros de microfita sintonizáveis

Abstract

This work aims to present tunable microstrip filters and antennas for applications in wireless communication systems, allowing variations in their resonant frequencies and bandwidths. Thus, in systems that present a high-intensity noise, changes in the operating frequency and bandwidth can provide higher reliability traffic of Information and improve the signal to noise ratio ofthe system. A technique was proposed to tune these devices, which consists in tilting the ground plane ofthese devices and vary the corresponding inclination angle as needed to meet the desired performances. Filters and antennas were designed using both circuit and transmission line theories combined with the tilted ground plane technique. Thereafter simulation was performed using the commercial software Ansoft-HFSS in order to validate the theoretical results. Furthermore several prototypes were built and measured using a vector network analyzer. A good agreement between measured and simulated results was observed. The obtained results showed an increase of up to 140% in the bandwidth ofthe filters and a range of up to 31% in resonant frequency of the studied antennas. Consequently by analyzing the performances of the considered microstrip devices it was observed that the application ofthe technique of tilted ground plane provides a considerable increase in the filters bandwidths and a signifícant percentage change in the resonant frequency value ofthe antennas. Therefore this technique is adequate for adjusting the response of microstrip devices with applications in filtering and electromagnetic radiation.