Experimental study in Ku-band of the propagation inside Empty Substrate Integrated Waveguides

Abstract

In the last years a great number of substrate-integrated circuits has been developed. These circuits are a compromise between the advantages of waveguides: high-quality factor and low losses, and the advantages of planar circuits: low-cost and easy compact integration. Recently, a new methodology for manufacturing empty waveguides integrated in a planar substrate has been proposed. To manufacture this Empty Substrate-Integrated Waveguide, a rectangular hole is emptied in the substrate and plated. Finally, the structure is closed with two metallic covers that are soldered above and below the substrate. Hence, the Empty Substrate-Integrated Waveguide could be modeled with an ideal rectangular waveguide. However, the degree of error that this assumption implies has not been evaluated yet. This evaluation is imperative, since this new manufacturing process strongly differs from that of a traditional single-piece rectangular waveguide. Then, in this work, for the first time, the propagation constant of an Empty Substrate-Integrated Waveguide has been measured, and compared to the propagation constant of an equivalent ideal rectangular waveguide, in order to determine how accurately an Empty Substrate-Integrated Waveguide can be modeled with a rectangular waveguide, and if the design methods for rectangular waveguide devices can be directly transferred to this novel substrate-integrated waveguide.