Steven K. Jones, Robert L. Hinkle, Frank H. Sanders, and Bradley J. Ramsey

Abstract:

In recent years, there has been a significant increase in the number of reported cases of electromagnetic interference (EMI) to 3.7–4.2 GHz FSS earth stations from radar stations operating in the 3.1–.7 GHz band. The increase in reported interference cases has been largely attributed to the rapid growth of television receive-only (TVRO) and audio distribution receive-only (ADRO) earth stations, and the trend towards the use of digital modulations by satellite systems. As the FSS expands their use of spectrum below 3.65 GHz, EMI interactions are anticipated to further increase. Since the radars involved in the reported interference cases have been Federal Government systems, the National Telecommunications and Information Administration (NTIA) has investigated the causes of such interference and developed recommended solutions to these problems.

One recommendation of a joint working group that was formed in August 1997 and co-chaired by NTIA and the Federal Communications Commission (FCC) to discuss these EMI issues and recommend solutions was to gather technical data on Government radars operating in the 3.1-3.7 GHz band, in particular, those radars that operate near the upper band edge, and to make this information available to the FCC for dissemination to the private sector, in particular to current and prospective operators of adjacent band satellite earth stations.

The objectives of this report were to: 1) identify operational characteristics of representative Government radars operating in the 3.1–3.7 GHz¹ frequency band, 2) outline a procedure for assessing the potential for EMI from these radars to adjacent-band FSS earth station receivers, and 3) identify methods for mitigating any received EMI.

1. The radar operational and technical characteristics presented in the report are representative as of the date of the report. This report will be updated as the electromagnetic environment changes.

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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