Homogeneity Analysis of Ecological Paper-Based Substrates’ Dielectric Properties

This paper investigates the dielectric property homogeneity of two ecological paper-based substrates, Cupforma Natura and EraCup Natural, using a split-cylinder resonator at 10.03 GHz. The dielectric constant and loss tangent were measured at multiple surface points before and after exposure to 1,000 thermal shock cycles between $125{ }^{\circ} \mathrm{C}$ and $-45^{\circ} \mathrm{C}$. Cupforma Natura exhibited an increase in dielectric constant variation from 0.01457 to 0.07451, while EraCup Natural showed a smaller change from 0.00534 to 0.01586, indicating better $\varepsilon_{\mathrm{r}}$ stability. Interestingly, Cupforma Natura’s loss tangent variation improved after stress (from 0.00408 to 0.00067), whereas EraCup Natural’s increased (from 0.00070 to 0.00389). Both materials demonstrated adequate dielectric performance and robustness, confirming their potential for sustainable high-frequency electronic applications.