Systematic Study of the Effective Permittivity in a Periodically Drilled Substrate Integrated Waveguide

摘要

This paper presents the results of a systematic study of the effective permittivity in a Substrate Integrated Waveguide (SIW) in which arrays of air holes are added along the waveguide in order to synthesize a lower effective permittivity. The study has been performed with the commercial software tool HFSS. For each geometry analyzed, one period along the propagation direction has been simulated, and by applying periodic conditions, the obtained cutoff frequency of the waveguide provides its effective permittivity. Different hole patterns have been analyzed, and for each one, the effect of the variation of the hole diameters has also been studied. Such study demonstrates that the effective permittivity in the drilled guide cannot be rigorously approximated by a surface weighted average, mainly due to the drilling of the metal surfaces. The radiation by the air holes in the drilled SIW has also been studied, concluding that radiation losses are not important if some design considerations are followed.