On the Accuracy of Dielectric Characterization of Solid Materials by Open-Ended Coaxial Cable

In the field of electromagnetic characterization of solid materials, waveguides have long been regarded as the gold standard. However, when dealing with high-technology epoxy resins, this method can be inefficient as it may require a large amount of material resulting in a huge expense in manufacturing the prototype under test and associated additional costs. Alternatively, a method employing an in-house open-ended coaxial probe technology is presented in this work. Specifically, the proposed technique can be applied to broadband assess the dielectric properties of resins in a more cost-effective and non-destructive manner, utilizing a small amount of material. In the literature, it is well stated that the main drawback in the dielectric characterization of solid material by using open coaxial probe is the formation of air gaps at the probe tip-to-material interface. To overcome these limitations, we have designed an appropriate mechanical support. To evaluate the reliability of the method, experimental measurements were performed in the 6.4 GHz-8.2 GHz frequency range and then compared with standard waveguide measurements. This study demonstrates that the proposed system is a valid alternative for preliminary dielectric characterization of hard materials such as epoxy resins.