Dynamic UWB off-body radio channels — Human body shadowing effect

Abstract

Dynamic off-body ultra wideband channels are examined by way of anechoic chamber measurements at a 3–5 GHz frequency band in frequency domain with a help of a fast sweeping vector network analyzer. Five antenna locations on the body are selected: right wrist, left wrist with an antenna on the palm or back side, left arm (AL) and left ankle (LA). The off body node is set at a pole (PO). Two in-house designed and manufactured prototype antennas, dipole and double loop, are used in cases with both similar and dissimilar antennas in a link. Depending on the case, the path loss (PL) ranges between 46.2–87.9 dB. The LA-PO has the highest and AL-PO the lowest average PLs. The PL amplitudes follow the inverse Gaussian distribution. Based on the level crossing rate the LA-PO has the deepest fading conditions and the AL-PO is the most stable link. The LA-PO has the largest average fade duration (AFD) at the thresholds below 0 dB. The AFD is larger on the average with the dipole than the double loop. The comparison of similar vs. dissimilar antenna pairs shows no major difference in the performance.