3D Printed Varying Infill Density Thermoplastic Polyurethane Substrate Based Flexible Antennas For IoT Applications

This paper presents design, simulation and fabrication of 3D printed Thermoplastic Polyurethane (TPU) based flexible substrates of two infill densities (100% and 40%), its characterization and then fabrication of Microstrip Patch Antennas (MPAs) on TPU substrates for IoT applications and their comprehensive bending analysis. TPU is a melt processable elastomer having enabling properties such as flexibility, excellent tensile strength, printability which makes it suitable material for fabricating flexible and conformal antennas. Initially, RF characterization of 3D printed TPU substrate of two different infill densities 100% and 40% was carried out using standard ring resonator method for obtaining the dielectric constant (ε<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</inf>) and loss tangent (tanδ). MPAs were then designed and simulated using ANSYS HFSS and fabricated on these two different infill density substrates. The measured resonance frequencies for 100% and 40% infill density antennas were 2.45 GHz, and 2.46 GHz, respectively. A comprehensive bending analysis was carried out to gauge the suitability of fabricated antennas for IoT applications. The measured results for all fabricated antennas are found to be well in agreement with the results of simulation.