Body Wearable Diversity Antenna Systems for Increased Antenna Performance

Body wearable antennas are needed in the context of Tactical Network Communications for the Land Warrior/Ground Soldier System ensembles. Specific bands of interest are 225-1000 MHz and 1350-2700 MHz. These frequency bands are particularly vulnerable to signal cancellations due to multipath. Moreover, body worn antennas often lead to gain losses (as much are 10 to 15dB less gain). As result of these challenges, during Phase I, we studied multiple body worn antennas in the context of MIMO. Channel capacity, hemispherical power patterns and diversity gain were considered as part of the objective parameters and metrics for evaluating the body-worn antennas ensembles. We showed that even 2 antennas, when positioned appropriately, can deliver significant diversity gain of 15dB as compared to a non-diversity systems. More importantly, we carried out a careful study of 2, 4, 6 and 8 antennas in various mounting locations and determined their metrics at 550MHz and 300MHz. As a result of this extensive study (mostly theoretical, but measurements for single body-worn antennas were conducted for validation) we have determined best locations and specific capacity expectations. During the option period we will also implement a diversity module using selection combining (SC) and consider its performance under several modulation systems and body-worn MIMO scenarios. During Phase II, we will follow this study and results with a demonstration of a body wearable diversity antenna system for increased channel capacity and improve communication links. Concurrently, we will consider optimizations for various warrior outfits, with the goal of delivering a practical prototype for transition. Size, weight and Power (SWAP) will certainly be a focus in our efforts to realize practical diversity antennas for body worn communications.