Evaluación de las prestaciones de filtros de orden elevado implementados con la nueva guía vacía integrada en sustrato

Abstract

In the last years a great number of substrate integrated circuits has been developed. These new circuits are a compromise between the advantages of classical waveguide technologies, such as high quality factor and low losses, and the advantages of planar circuits, such as low cost and easy compact integration. Although their quality factor and losses are better than for planar circuits, these characteristics are worse than in the case of waveguides, mainly due to the presence of the dielectric substrate. In order to improve the performance of the integrated circuits, a new methodology for manufacturing empty waveguides, without dielectric substrate, but at the same time completely integrated in a planar substrate has been recently proposed. A wide band transition with return losses greater than 20 dB in the whole bandwith of the waveguide allows the integration of the empty waveguide into the planar substrate, so that the waveguide can be directly accessed with a microstrip line. Therefore a microwave circuit integrated in a planar substrate, but at the same time with a very high quality factor (measured quality factor is 4.5 times higher than for the same filter in SIW) and very low losses was successfully achieved. In this work the performance of this new technology is tested through the simulation and measurement of high order filters (8 and 9 cavities filters).