Biosymbiotic 3-D-Printed Planar Inverted-F Antenna

This article demonstrates a 3-D-printed antenna designed for unobtrusive wearable applications operating in the 915 MHz UHF band. The antenna possesses desirable biosymbiotic characteristics to enhance its wearability, including flexibility, stretchability, breathability, and permeability. Specifically, the design adopts a serpentine meshed configuration to construct a low-profile planar inverted-F antenna (PIFA). The dielectric properties of the applied 3-D-printing material and the corresponding 3-D-printing fabrication features are investigated for optimization of the PIFA structure. The antenna input impedance is not only restrained to the scope of 50- $\Omega $ impedance matching, but can be also extended by design to complex values, allowing freedom of direct integration with radio frequency identity (RFID) or wireless power transfer (WPT) systems. The measured results demonstrate that the proposed PIFA owns a stable bandwidth of 4.3% regardless of the body influence, with a realized gain of 0 and -4.9 dBi in the OFF-body and ON-body scenarios, respectively. Additionally, the antenna performance is stable within the mechanical deformation regime naturally occurring on the body. In comparison with other 3-D-printing antennas for OFF-body communications, the proposed serpentine meshed PIFA owns attractive biosymbiotic characteristics and satisfactory electromagnetic performance for direct deployment on the skin.