Design of an Electromagnetic Characterization System for Materials at Low and High Temperature

The aerospace industry has experienced remarkable advances through the adoption of composite materials and 3D technologies due to their optimal strength‐to‐weight ratio. However, the extreme temperature gradients in the space environment present considerable challenges for the stability and performance of these materials. This paper presents the design and proof‐of‐concept validation of a non‐resonant electromagnetic characterization system to evaluate relative permittivity in dielectric materials under varying thermal conditions. The system utilizes dual‐line microstrip technology, employing a phase extraction method to achieve precise measurements of effective permittivity. Both the dielectric loss tangent and the real part of the relative permittivity are analyzed for composite materials, including FR‐4, ROGERS 4350B, and CuClad‐250. These materials are tested over a wide frequency range (500 MHz–20 GHz) and under temperature conditions spanning −55°C to 80°C. The study incorporates a validation phase conducted at room temperature, that includes both electromagnetic simulations and measurements, followed by measurements in a thermal chamber to evaluate material performance under varying thermal conditions. Although this study represents an initial prototype phase with planned improvements, the system shows consistency and reliability in measurements, highlighting the significant variation of permittivity with temperature.