High-Performance Coplanar Waveguide to Empty Substrate Integrated Coaxial Line Transition

Abstract

Abstract-Very recently, a new empty coaxial structure, entirely built with printed circuit boards, has been proposed. The resulting coaxial line has low radiation, low losses, high quality factor, mono-mode propagation and is non-dispersive. Also, and conversely to other coaxial line designs, the fabrication process of this empty coaxial line permits to easily adjust the dimensions of the inner and outer conductors. Thus, the response of the coaxial line can be tailored by designing the shape of the conductors appropriately. Up to now, this novel coaxial line has not been successfully integrated in a planar substrate, since a working transition to a traditional planar line has not been defined yet. Therefore, in this paper, a novel and high-quality transition from coplanar waveguide to this new and versatile empty coaxial line is proposed. With this transition, the coaxial line is completely integrated in a planar circuit board, so that it truly becomes an empty substrate integrated coaxial line. The proposed transition has been fabricated and assembled. Both full-wave simulated and measured results show an excellent agreement. Therefore, the proposed transition is suitable to develop completely substrate integrated planar components for applications in wideband communication systems that require very high-quality responses and protection from external electromagnetic interferences. In order to show this fact, this new transition has been applied to integrate a high-performance empty coaxial line filter in a planar substrate. The measured response of this filter is excellent, and proves the goodness of the proposed transition that has enabled, for the first time, the complete integration of an empty coaxial line in a planar substrate.Index Terms-Empty substrate integrated coaxial line, ESICL, substrate integrated coaxial line, SICL, substrate integrated waveguide, SIW, substrate integrated circuit, SIC, bandpass filter.

Design and Performance of a High- $Q$ Narrow Bandwidth Bandpass Filter in Empty Substrate Integrated Coaxial Line at $K_{u}$ -Band

“…In order to further explore the advantages of empty substrate transmission lines, we present in this paper a planar coaxial filter with low losses and high Q-factor for operation at K u -band. Due to its non-dispersive behaviour, coaxial transmission lines are commonly employed for wideband filtering applications [6]. However, the advantages of these coaxial filters for narrow or very narrow passband operation are analyzed in this work.…”

Wide‐bandwidth thru‐reflect‐line calibration for empty substrate‐integrated coaxial line with grounded coplanar transitions

“…Recently, some devices have been developed using ESICL: transition to grounded coplanar (GCPW) lines, a wideband bandpass filter and a high‐Q narrow bandwidth bandpass filter . At the same time, specific analysis techniques (BI‐RME, FEM) for ESICL have also been carried out, which allow the full‐wave analysis and design of ESICL devices …”

“…ESICL is built up by piling conventional substrate layers . The general topology can be observed in Figure ; it is composed of five separated PCB layers accordingly aligned and metalized to generate a suspended rectangular conductor within an empty guide.…”

“…Construction of a typical ESICL structure: (left) separated layers; (right) cross‐section [Color figure can be viewed at wileyonlinelibrary.com]…”

“…1 ESICL is built up by piling conventional substrate layers. 3 The general topology can be observed in Figure 1; it is composed of five separated PCB layers accordingly aligned and metalized to generate a suspended rectangular conductor within an empty guide. With the available transition GCPW-ESICL, it has been possible to integrate a dielectricless TEM line in a planar substrate.…”