High-k and low-loss thermoplastic composites for Fused Deposition Modeling and their application to 3D-printed Ku-band antennas

Four types of high-permittivity and low-loss electromagnetic composites for Fused Deposition Modeling (FDM) based on Cyclo-Olefin Polymer (COP) and Acrylonitrile Butadiene Styrene (ABS), reinforced by Ba_0.55Sr_0.45TiO₃, MgCaTiO₂, or TiO₂ co-fired micro-fillers, have been prepared and characterized up to 17 GHz using cavity resonators. Thin-sheet specimens made of 25% v/v COP-MgCaTiO₂, prepared by FDM, exhibit a relative permittivity ε_r of ~ 4.74 and loss tangent tanδ_d lower than 0.0018, while 25% v/v COP-Ba_0.55Sr_0.45TiO₃ specimens exhibit relative permittivity ε_r of ~ 4.92 and loss tangent tanδ_d lower than 0.0115. Meanwhile, 30% v/v COP-TiO₂ specimens exhibit a relative permittivity ε_r of ~ 4.56 and a record low loss tangent tanδ_d lower than 0.0014, while the 6% v/v ABS-Ba_0.55Sr_0.45TiO₃ specimens demonstrate relative permittivity ε_r of ~ 3.98 and loss tangent tanδd below 0.0088. Rectangular edge-fed patch antennas operating at ~ 17 GHz are fabricated using 3D printing to compare the size and performance against designs that used commercial microwave laminates.