3-D Printing of Conformal Antennas for Diversity Wrist Worn Applications

This paper presents for the first time the application of 3-D printing techniques for the development of conformal antennas for diversity wrist worn wireless communications. Three processes are described with the common challenge of depositing the metallic layers of the antennas on a bracelet fabricated using fuse filament fabrication. The first is a multistep process that combines adding a layer to smooth the surface of the band, aerosol jetting the metallic tracks, flash curing, and then electroplating. The second combines painting the metallic layers by hand and then electroplating. The last process uses a single machine to fabricate both the bracelet and then the metallic layers by means of a direct write system with silver conductive ink. The wrist worn antennas are presented and its performances on the human wrist are discussed. All antennas cover 2.4 and 5.5 GHz used for WLAN communication with the reflection coefficients less than -10 dB. The diversity wrist worn antennas system is developed for the final two processes. Three WLAN antennas are fabricated at different positions and shape angles within the bracelet. In terms of communications systems, the advantage of this configuration is that it can increase coverage. The radiation patterns of the antenna are nearly omnidirectional in free space and directional on the human wrist. When the patterns of the three antennas are combined together, the coverage for the communication system improves. Simulation results of all antenna designs and studies using the finite integration technique agree well with experimental measurement results. The main motivation of this paper is to investigate alternative additive manufacturing methods for the development of conformal diversity antennas on customized 3-D printed parts.