Analysis of Heating, Ventilation and Air Conditioning Ducts as a Radio Frequency Communication Channel

Pavel V. Nikitin. Analysis of Heating, Ventilation and Air Conditioning Ducts as a Radio Frequency Communication Channel. Ph.D. Thesis, Carnegie Mellon University, Pittsburgh, PA, 2002.

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Abstract

A typical HVAC duct system is a network of interconnected hollow metal pipes which can serve as waveguides and carry electromagnetic waves. This work presents an analysis of this system as a radio frequency communication channel. Two main parts of the analysis include channel modelling and antenna design. The propagation modelling approach used here is based on the waveguide mode theory and employs the transfer matrix method to describe propagation through various cascaded HVAC ele- ments. This allows one to model the channel response in the frequency domain. Impulse response characteristics of the ducts are also analyzed in this work. The approximate transfer matrices of cylindrical straight sections, bends, and tapers are derived analytically. The transforming properties of cylindrical T-junctions are analyzed experimentally. Antenna designs in waveguides and free-space are different. In waveguides, mode excitation characteristics are important as well as the impedance match. The criteria for antenna design in waveguides are presented here. Antennas analyzed in this work are monopole antennas, dipole antennas, and antenna arrays. The developed model can predict both channel response and antenna characteristics for a given geometry and dimensions of the duct system and the antennas. The model is computationally effi- cient and can potentially be applied to duct systems of multiple story buildings. The accuracy of the model has been validated with extensive experimental measurements on real HVAC ducts.

BibTeX

@PHDTHESIS{nikitin_thesis_2002,
  author = {Pavel V. Nikitin},
  title = {Analysis of Heating, Ventilation and Air Conditioning Ducts as a
	Radio Frequency Communication Channel},
  school = {Carnegie Mellon University},
  year = {2002},
  address = {Pittsburgh, PA},
  month = {Aug.},
  abstract = {A typical HVAC duct system is a network of interconnected hollow metal
	pipes which can serve as 
	waveguides and carry electromagnetic waves. This work presents an
	analysis of this system as a 
	radio frequency communication channel. Two main parts of the analysis
	include channel modelling 
	and antenna design. 
	The propagation modelling approach used here is based on the waveguide
	mode theory and 
	employs the transfer matrix method to describe propagation through
	various cascaded HVAC ele- 
	ments. This allows one to model the channel response in the frequency
	domain. Impulse response 
	characteristics of the ducts are also analyzed in this work. 
	The approximate transfer matrices of cylindrical straight sections,
	bends, and tapers are derived 
	analytically. The transforming properties of cylindrical T-junctions
	are analyzed experimentally. 
	Antenna designs in waveguides and free-space are different. In waveguides,
	mode excitation 
	characteristics are important as well as the impedance match. The
	criteria for antenna design in 
	waveguides are presented here. Antennas analyzed in this work are
	monopole antennas, dipole 
	antennas, and antenna arrays. 
	The developed model can predict both channel response and antenna
	characteristics for a given 
	geometry and dimensions of the duct system and the antennas. The model
	is computationally effi- 
	cient and can potentially be applied to duct systems of multiple story
	buildings. The accuracy of the 
	model has been validated with extensive experimental measurements
	on real HVAC ducts.},
  owner = {henty},
  pdf = {Nikitin_PhDThesis.pdf},
  timestamp = {2006.06.18},
}

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