Characterization of Wearable and Implanted Antennas: Test Procedure and Range Design

A method for measuring deembedded antenna parameters of wearable and implanted antennas for on-body communications is presented. It consists of a tapered flat phantom in order to characterize an antenna's general ability to excite surface waves traveling along the boundary between body tissue and free space, expressed by an angular on-body antenna gain. The design offers a test zone large enough for most typical wireless body area network devices up to smartphone size while minimizing the required amount of tissue-simulating material. The designed antenna test range is validated in the 2.4 GHz industrial, scientific and medical (ISM) band. To showcase the applicability to a realistic application, different designs of antennas integrated into an implanted pacemaker are characterized by their on-body gain patterns. A comparison of their performance in in situ path-loss measurements reveals a clear relation to the on-body gain patterns and indicates that this parameter is a suitable measure for enabling educated antenna design for on-body applications.