Snap-On Buttons as Detachable Shorting Vias for Wearable Textile Antennas Shengjian Jammy Chen ∗ Damith Chinthana Ranasinghe † Christophe Fumeaux ∗ Abstract — This paper demonstrates that commer- cial snap-on buttons can be utilized as detachable shorting vias for wearable textile antennas. As a consequence, modularity in antenna characteristics can be obtained based on a common initial design. As an illustration, a patch antenna with different configurations of shorting vias is designed and ex- perimentally characterized. In this design, adapted from a recently reported modular snap-on-button- based wearable antenna, four sets of two back-to- back male snap-on buttons affixed within a two- layered substrate are used as detachable patch hold- ers and/or modular shorting vias to the ground plane. By engaging selected male buttons from the ground plane with female buttons to form shorting vias, various antenna patterns can be selected. 1 INTRODUCTION Numerous novel materials are emerging as conduc- tors for flexible and wearable electronics. This is particularly important for antennas, since conven- tional metallic materials usually have very limited mechanical resilience. Those materials include con- ductive textiles [1], conductive inks [2], conduc- tive threads [3] and conductive polymers [4, 5]. In particular, conductive textiles are one of the most promising classes of conductors for wearable appli- cations [6], as they are highly flexible and conduc- tive, light-weight, robust, low-cost and garment- integrable. A large number of antennas based on conduc- tive textiles including patch antennas [7, 8], ultra- wideband antennas [9, 10], substrate-integrated waveguide (SIW) based antennas [11–13] and a modular antenna [14] have been reported in the literature. Some of these designs require shorting point(s) and shorting wall(s), for example, to cre- ate a planar inverted-F antenna (PIFA) structure or form a cavity. T o realize these shorts, conductive textiles [15], embroidered vias [16], eyelets [11] and commercial snap-on buttons [14] have been pro- posed and used due to their compatibility and easy implementation with fabric materials. Especially, snap-on buttons possess an invaluable advantage ∗ The School of Electrical and Electronic Engineer- ing, The University of Adelaide, Adelaide, 5005, SA, Australia, e-mail: Shengjian.chen@adelaide.edu.au; christophe.fumeaux@adelaide.edu.au † Auto-ID Lab, The School of Computer Science, The University of Adelaide, Adelaide, SA 5005, Australia, e-mail: damith.ranasinghe@adelaide.edu.au                                      ! !   "  #$         %    $ $ $ & ' ( # ))     *&(+ Figure 1: Antenna configuration and dimensions. (a) Top view. (b) Side view. (c) Configuration: the an- tenna consists of an interchangeable radiating patch module and a common base which contains a two- layered substrate, a ground plane, a microstrip feed and snap-on buttons. Shorting vias are created by engaging female buttons on the back of the ground plane. Di- mensions (in mm): W 1 = 40, W 2 = 19.5, W 3 = 13, W 4 = 6.5, L1 = 40, L2 = 18.5, L3 = 13.5, L4 = 15, h = 3.2. that can enhance modularity of antenna designs, namely repeated detachability. T o further demon- strate this capability, the utilization of snap-on but- tons as detacheable shorting vias is presented in this paper. T o this end, a modular antenna adapted from [14] with interchangeable beam direction is designed and experimentally characterized. 978-1-4673-9811-4/16/$31.00 ©2016 IEEE 521