Browsing by Author "Huang, YF"

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A novel and efficient hybrid model of radio multipath-fading channels in indoor environments
(2003-03-01)
Tarng, JH
;
Liu, WS
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Huang, YF
;
Huang, JM
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電信工程研究所
This paper presents a novel and efficient hybrid model combining a two-dimensional (2-D) site-specific model and a statistical model to characterize multipath fading in indoor environments. The site-specific, model describes the propagation effects of interior walls and building walls. The latter model characterizes the effect of scattering due to rough surface boundaries and/or randomly positioned scatterers such as furniture and personnel, which significantly affects small-scale fading. The hybrid model is computationally efficient since only the 2-D site-specific model is needed. In addition to Accurately predicting mean field strength, the model can effectively quantify the relative mean contribution of diffused scattering with a factor r. The factor is also an effective index to quantify the cluttering strength of the propagation environment: 1) light-cluttering situation r less than or equal to 0.35 and 2) heavy-cluttering situation r greater than or equal to 0.65. Some blind tests validate the effectiveness of the model. A large amount of experimental data for 2.44-GHz radio at many different sites shows that a Nakagami distribution describes the fading distribution well.
Morphology control of silicon nanotips fabricated by electron cyclotron resonance plasma etching
(2006-01-01)
Hsu, CH
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Huang, YF
;
Chen, LC
;
Chattopadhyay, S
;
Chen, KH
Formation of well-aligned silicon nanotips etched monolithically from a silicon substrate has been demonstrated. The effect of the process temperature on the physicochemical etching of silicon and subsequent fabrication of these nanotips has been investigated. 2.2-mu m-long nanotips were formed at the process temperature of 250 degrees C and then decreased in length with increasing process temperature. Above 800 degrees C, the formation of the silicon nanotips was inhibited. Spectroscopic evidence attributes this fact to the efficient formation of silicon carbide thin film at higher process temperatures, instead of discontinuous nanomasks at lower process temperatures that prevent etching of the substrate. Another reason for this inhibited formation of nanotips is the reduced etching rate of the silicon by agents such as atomic H at higher process temperatures. (c) 2006 American Vacuum Society.