Accurate broad-band measurement of complex permittivity using striplines

Abstract

The RF and microwave industries are dependent on high performance materials, such as advanced polymers and low temperature cofired ceramics (LTCC), amongst others, which are designed to guide electromagnetic fields. Accurate characterization of these materials is essential for the optimal design of microwave devices and this can be achieved through knowledge of the complex permittivity of the materials involved. A technique for the accurate characterization of the complex permittivity of linear materials over a broad range of microwave frequencies is presented. The technique involves measurement of the scattering parameters of two different length striplines built on the substrate to be characterized, de-embedding the effects of the input/output connectors, and extracting the complex permittivity from de-embedded scattering parameters.