Complex Permittivity of Advanced Dielectrics Across the 6G Frequency Band




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As industry moves to higher frequencies with the use of 5G telecommunication (up to 38 GHz) and automotive radar (up to 77 GHz), electrical characteristics for a wide range of materials are needed. To potentially employ these materials with millimeter-wave ICs (MMICs), quantitative knowledge of the materials’ dielectric properties across a broad millimeter-wave band is necessary. To solve this, we created a nondestructive measurement of the complex relative permittivity, εr = ε′ + jε′′, on some possible MMIC packaging materials, ranging from epoxy composites to liquid crystal polymers as well as laminates and bond plys. Measurements using phase-sensitive transmission over the WR3, WR5, and WR8 frequency bands (90 to 325 GHz) show that ε′ can vary significantly in traditional packaging materials. For example, a known material at low frequencies, Vectra A130, is shown to be dispersive at high frequencies with a slope of 0.17%/GHz. Thus, across the WR5 band the ε′ changes from about 1.95 at 140 GHz to about 2.8 at 220 GHz. Results like this could be used to model the performance of packaged MMICs in HFSS and to design composites or other types of MMIC packaging material to have tailored values of ε′ and in the loss tangent for better system results. As an example of modeling, electromagnetic modeling results for an in-package horn antenna molded from one of the dielectric composites measured are presented.



Physics, Condensed Matter, Engineering, Electronics and Electrical