Novel empty substrate integrated waveguide for high performance microwave integrated circuits

"(c) 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works."Abstract Over 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 a dielectric substrate, but at the same time completely integrated in a planar substrate, is proposed in this work. A wideband 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 the substrate integrated waveguide), and very low losses is successfully achieved.This work was supported by the Ministerio de Ciencia e Innovacion, Spanish Goverment, under Research Project TEC2010-21520-C04-03 and Research Project EC2010-21520-C04-01, and by the Autonomous Government of Castilla-La Mancha under Research Project PPII10-0047-0220.Belenguer Martínez, Á.; Esteban González, H.; Boria Esbert, VE. (2014). Novel empty substrate integrated waveguide for high performance microwave integrated circuits. IEEE Transactions on Microwave Theory and Techniques. 62(4):832-839. https://doi.org/10.1109/TMTT.2014.230963783283962