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Tham khảo tài liệu 'advances in spacecraft technologies part 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 70 Advances in Spacecraft Technologies X mm c Fig. 11. Spatial distribution of delay spread with use of 0.093 rriarea of the radio absorber computed from a full UWB 3.1 -10.6 GHz b low-band UWB 4.2 ffl.8 GHz and c high-band UWB 7.3 - 7.9 GHz . Measurements and Characterization of Ultra Wideband Propagation within Spacecrafts Ó Proposal of Wireless Transmission for Replacing Wired Interface Buses 71 Fig. 12. Cumulative distribution function of delay spread. Relative area of radio absorber i Fig. 13. Received energy loss caused by the radio absorber. 5. Conclusions Ultra wideband from 3.1 to 10.6 GHz from 4.2 to 4.8 GHz and from 7.3 to 7.9 GHz and cw 6.85 GHz propagation were measured and characterized inside a small spacecraft. Major findings are summarized as follows While cw resulted in nearly 30-dB fading at several dead spotsicaused by multipath UWB yielded no dead spots. The UWB systems have therefore an advantage over narrowband systems from the viewpoint of reducing fading margins. A bandwidth over 400 MHz or a fractional ba ndwidth over 6 was capable of reducing the fading depth by approximately 2 dB in conductive closed spaces like spacecraft. The conductive enclosures caused abundant multipaths and as a result long delay spreads particularly when .
