NTIA Report TR-01-387

Predicted and Measured Field Strengths in the Boulder, Colorado, Area from
Two Proposed Terrestrial Digital Television Tower Sites

May 2001

Christopher L. Holloway, Frank H.Sanders, and Paul M. McKenna

Abstract: A study was performed to determine the increase in ambient electromagnetic field strengths that would result from a proposal to locate a cluster of terrestrial digital television (DTV) transmission towers in proximity to the Department of Commerce (DOC) Laboratories in Boulder, Colorado. The primary objective of this study was to assess the impact on a broad range of Federal Government research and metrology programs that depend upon the relatively quiet radio-frequency electromagnetic environment. Radio-wave propagation measurements were performed for two terrestrial DTV frequencies (533 MHz and 772 MHz), and used to verify predicted DTV electric field strengths obtained from the DOC Irregular Terrain Model (ITM). The measured data were also used to determine the variation in received signal strength over small distance intervals. Radio-wave propagation measurements were performed at both frequencies using two possible mountaintop transmitter locations, Eldorado Mountain and Squaw Mountain. The first (Eldorado Mountain) affords substantial line-of-sight coverage over the Boulder area, and the second (Squaw Mountain) affords only indirect (diffractive) coverage over the same area. The two propagation conditions from each site, direct and indirect, respectively, are compared to the ITM predictions. The relative variations in measured and predicted signal strengths are compared as a function of frequency and of propagation conditions. Measured and predicted data were found to be in close agreement. This provides confidence that the theoretical predictions of received signal strengths at given locations in the Boulder area are accurate. It was found that in some locations, the ambient field strengths for 1 MW of transmitter power from a single station will exceed 1 V/m.

Keywords: digital television (DTV), field strength measurements, Irregular Terrain Model (ITM), National Radio Quiet Zone (NRQZ), propagation modeling, spectrum survey

• Report – excluding figures 1 – 80 and appendices

• Figures 1 – 10
• Figures 11 – 20
• Figures 21 – 30
• Figures 31 – 40
• Figures 41 – 50
• Figures 51 – 60
• Figures 61 – 70
• Figures 71 – 80
  
  
• Appendix A, Measured E-Field Strengths of the 1998 and 2001 Spectrum Survey:
  • Appendix A, Figures 1 – 11
  • Appendix A, Figures 12 – 21
  • Appendix A, Figures 22 – 31
  • Appendix A, Figures 32 – 43
    
    
• Appendix B, Measured Power Levels:
  • Appendix B, Figures 1 – 20
  • Appendix B, Figures 21 – 34

Disclaimer: Certain commercial equipment, components, and software are identified in this report to specify adequately the technical aspects of the reported results. In no case does such identification imply recommendation or endorsement by the National Telecommunications and Information Administration, nor does it imply that the equipment or software identified is necessarily the best available for the particular application or uses.

To request a reprint of this report, contact:r /> Margaret Luebs, Publications Officer
Institute for Telecommunication Sciences
Voice: (303) 497-3572
info@its.bldrdoc.gov

For technical information concerning this report, contact:r /> Frank Sanders, Electronics Engineer
Institute for Telecommunication Sciences
Voice: (303) 497-7600
fsanders@its.bldrdoc.gov