Synthesis and dielectric characterisation of a low loss BaSrTiO₃/ABS ceramic/polymer composite for fused filament fabrication additive manufacturing

Composite polymer/ceramic filaments for material extrusion-based fused filament fabrication additive manufacturing, using barium strontium titanium oxide (BST) ceramics and acrylonitrile butadiene styrene (ABS) thermoplastics were produced; their dielectric and physical properties have been characterised for the first time. The dielectric properties, relative permittivity (ε_r), quality factor (Q×f) and dielectric loss (tanδ) were measured as a function of ceramic solid loading (%) at 5 GHz for 3D printed samples. A relative permittivity ε_r = 6.05, Q×f = 10,433 GHz and dielectric loss tanδ = 0.007 were obtained for a BST/ABS ceramic polymer composite, with 50 wt% (15 vol%) solid loading. The composite materials exhibit reduced dielectric losses compared to standard laminates currently used in the radiofrequency (RF) and telecommunications industry. Based on polymer/ceramic composite filament, a prototype microstrip patch 5 G antenna and a hemispherical dielectric lens were designed and manufactured. Through testing, it shows good antenna performance with a centre frequency of f0 = 3.78 GHz and a (−10 dB) bandwidth of 90.6 MHz. The dielectric lens increased the antenna gain by 3.86 dBi.