PDMS-based composites with stable dielectric properties at varied frequency via Sr-doped CaCu3Ti4O12 nanowires for flexible wideband antenna substrate

With the development of new mobile communication systems, the composite substrate used for the wideband antennas will show a suitable dielectric constant, low dielectric loss, and good dielectric stability in a wide frequency range. In this work, a kind of dielectric filler, Sr 2+ -doped CaCu 3 Ti 4 O 12 nanowires (Ca 1− x Sr x Cu 3 Ti 4 O 12 NWs, x SCCTO NWs), was synthesized via a two-step hydrothermal method for the first time. The composites were then prepared by adding the obtained filler to polydimethylsiloxane (PDMS). Results revealed that Sr 2+ doping can significantly reduce the dielectric loss of composites and stabilize both the dielectric constant and the dielectric loss in a wide frequency range compared with those of CCTO NWs–PDMS composites. Moreover, 0.4SCCTO NWs–PDMS composites exhibit high thermal stability, tensile strength, breakdown strength, and energy density. These properties effectively broaden the frequency range of the PDMS based composites, which are very suitable for the application in flexible wideband antenna substrate materials.