| A measurement campaign was undertaken at the Camp Lejeune North Carolina (CLNC) Military Operations on Urban Terrain (MOUT) site to characterize subterranean RF propagation. Previous related studies for subterranean wireless communications purposes have focused on railroad, auto, subway and mine tunnels having wide cross-section dimensions exceeding 3 meters. An overlooked infrastructure element with significant tactical communications value is the municipal sewer tunnel network. As long as the sewer line is accessible and navigable by the warfighter, it will have utility and so interior diameters down to 1-meter are not out of the question. The CLNC MOUT subterranean tunnel complex has such a narrow diameter, as well as representative L-bends and T-junctions. A series of path loss measurements were conducted for various spatial separations of transmit and receive antennas in the Ultrahigh Frequency (UHF) band covering 374 MHz as well as the 900 MHz and 2.4 GHz Industrial, Scientific, and Medical (ISM) bands. In contrast to the wider, predominately vehicular tunnels, these transmission wavelengths are critically close to the sewer tunnel dimensions. The test methodology is explained and the results are compared with predictions based on modeling the sewer tunnel as an oversized, lossy circular waveguide. The unique findings presented herein are applicable to other tightly confined spaces such as natural cave passageways. |
| Erik Kjeldsen received the B.E. degree in electrical engineering and mathematics from Vanderbilt University in 1983 and the M.S. degree in operations research from Georgia Institute of Technology in 1992. He began his engineering career at IBM in Manassas, VA, serving as lead systems engineer on the AN/BSY-1 submarine spherical array signal conditioner. He subsequently worked at E-Systems in Falls Church, VA on the Commanders’ Tactical Terminal (CTT). He joined Scientific Research Corporation (SRC), Atlanta, GA, in 1992 and is currently a senior systems engineer. He has twenty-three years of professional engineering experience, with seventeen years focused on the design, development, analysis, and test of tactical communications systems for the Army, Air Force, Navy, and DARPA. His technical interests include wireless communications, software-defined and cognitive radio, wavelet applications, digital video/imagery processing and compression, and communications waveform/network simulation. |