Bending Effects on a Fabric-Based Antenna for Wearable Applications

Abstract

This paper studied the cylindrically bending effects of an fabric-based antenna. The fabric-based antenna consists of a meandered feeding line a patch. Two open stubs are inserted in the meandered feeding line to provide two transmission zeros near the passband. The bandwidth of fabric-based antenna was 2.5-4.6 GHz with the maximal gain of -0.42 - -3.1 dBi. Two bending orientations on hollow and solid cylinders of the fabric-based antenna were compared for simulation of human body structure. For transverse bending, the shape of radiation pattern and gain were almost identical for solid and hollow cylinders. A slightly lower bandwidth was observed due to the dielectric material of solid cylinder cannot neglected. For longitudinal bending, the maximal gain and bandwidth were affected because the resonance path was changed. The significant reduction of maximal gain was observed for longitudinal bending on hollow cylinder because radiation gain was loss to ground. Although the maximal gain at the middle band was almost similar on solid cylinder for longitudinal bending, the directivity at various frequencies was changed on solid cylinder because two dips were found. Results demonstrate the bending behavior of wearable antenna should be carefully monitored for on-body wireless communications.