Experimental study on transmission characteristics of high permittivity tape transmission line at millimeter-wave frequencies

High permittivity tape transmission line was proposed for mass-produced dielectric waveguides. This guide consists of a high permittivity dielectric tape inserted into the horizontal midplane of a below cutoff parallel metal waveguide. From the theoretical investigation, this guide was found to exhibit low-loss performance as well as flat dispersion characteristics in a wide frequency region. And moreover, the transmission loss was relatively unaffected by loss tangents of the high permittivity materials. Such theoretical results were verified by experimental investigation in this paper. The high permittivity dielectric tapes, having relative dielectric constants of 90 and 197, were selected and the transmission characteristics were measured. A flat dispersion curve, the normalized phase constants being around unity, was obtained in the wide frequency region from 25 GHz to 60 GHz, and the transmission loss was measured to be less than 12.5 dB/m in this frequency range.