Perry F. Wilson, Eldon J. Haakinson, and Roger A. Dalke

Abstract: High level electromagnetic fields can upset and damage electronics, as well as disrupt or disable computer software. Thus, high power radio frequency (RF) fields pose a threat to critical infrastructures such as telecommunications. This report examines the vulnerability of public and emergency telecommunications networks to high power RF fields, at the network and nodal levels. The assessment of network level vulnerability requires an examination of the system architecture and how redundancy and robustness are used to compensate for nodal loss or overload. The overall public telecommunications network has sufficient redundancy and capacity to withstand the loss of even multiple nodes. A full system collapse is not envisioned as a possible scenario. However, large local blackouts are possible. The assessment of nodal level vulnerability involves estimating the coupling of high level RF fields to sensitive equipment located at a node. Neither public network switching stations nor cellular base stations are intentionally hardened against high level RF fields. Typical steel reinforced concrete walls provide little shielding for frequencies above a few hundred MHz. Thus, a switching station could be disrupted (10 to 100 thousand users) by a high power RF device in this frequency range, although the probability of disruption is difficult to assess due to the variety and complexity of building layouts. Wireless base stations are highly vulnerable to high power fields coupling via the antennas.

Keywords: vulnerability; critical infrastructure protection; high power RF fields; public switched telephone network; shielding

Disclaimer: Certain commercial equipment, components, and software may be 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.

For questions or information on this or any other NTIA scientific publication, contact the ITS Publications Office at ITSinfo@ntia.gov or 303-497-3572.

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