Dielectric Characterization of Anisotropic 3D-Printed Biodegradable Substrates Based on Polylactic Acid [Application Notes]

3D-printed dielectric substrates are manufactured using additive manufacturing (AM) technology. With CAD/CAM, rapid, accurate, and automatic manufacturing of objects with different characteristics and almost any geometry is possible. With 3D printing processes, objects are formed layer by layer, and complicated shapes can easily be created. For this reason, in the last decade, AM has seen a great boom in the development of RF and microwave circuits. Some applications that benefit from AM are metamaterials [1]-[3], antennas [4]-[5], and selective surfaces [6], among others. Most of the RF and microwave circuits reported in previous works are designed considering the dielectric substrate as an isotropic material; therefore, large differences are found between the measured and the simulated results [6]-[8]. These variations are largely due to the fact that the manufacturing standards generally include a mixture of materials inside the substrates with a periodic arrangement [9], and this favors dielectric anisotropy in the substrates. Consequently, the study of these materials is of great importance to the scientific community. This article is intended for designers who wish to tailor the dielectric characteristics of a substrate for microwave circuits, noting that anisotropy will manifest itself at lower frequencies when the internal structure of the printed material is modified.