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Hironobu YAMAMOTO Jian ZHOU Takehiko KOBAYASHI
Ultra wideband (UWB) technologies are expected to be used in ultra-high-speed wireless personal area networks (WPAN) and wireless body area networks (WBAN). UWB human electromagnetic phantoms are useful for performance evaluation of antennas mounted in the vicinity of a human body and channel assessment when a human body blocks a propagation path. Publications on UWB phantoms, however, have been limited so far. This paper describes the development of liquid UWB phantom material (aqueous solution of sucrose) and UWB arm and torso phantoms. The UWB phantoms are not intended to evaluate a specific absorption rate (SAR) in a human body, because UWB devices are supposed to transmit at very low power and thus should pose no human hazard.
Hironobu YAMAMOTO Masato KOIWAI Takehiko KOBAYASHI
This paper describes ultra wideband (UWB) radio propagation measurements and modeling for wireless body area network (WBAN) applications in different environments. Several propagation measurement campaigns and associated modelings were carried out in either a radio anechoic chamber or a specific room type; however, dependence of the radio propagation on surrounding environments was not studied. Multipaths (mainly reflected from floor, ceiling, and walls) highly depend on the environment. To address this problem, radio propagation around the human body was measured in a radio anechoic chamber and four different-sized rooms. Parameters in a conventional loss model derived from the measurements were found to significantly diverge and depend on room volume and line-of-sight (LOS)/non-LOS (NLOS) cases. A modified model considering the impact of room volume has been proposed for the LOS/NLOS cases. Different propagation mechanisms were discussed along with parameter derivation. Probability distributions for the UWB propagation losses were also examined.