NTIA Report TR-06-444

Effects of RF Interference on Radar Receivers

September 2006

Frank H. Sanders, Robert L. Sole, Brent L. Bedford, David Franc, Timothy Pawlowitz

Abstract: This report describes the results of interference tests and measurements that have been performed on radar receivers that have various missions in several spectrum bands. Radar target losses have been measured under controlled conditions in the presence of radio frequency (RF) interference. Radar types that have been examined include short range and long range air traffic control; weather surveillance; and maritime navigation and surface search. Radar receivers experience loss of desired targets when interference from high duty cycle (more than about 1-3%) communication-type signals is as low as -10 dB to -6 dB relative to radar receiver inherent noise levels. Conversely, radars perform robustly in the presence of low duty cycle (less than 1-3%) signals such as those emitted by other radars. Target losses at low levels are insidious because they do not cause overt indications such as strobes on displays. Therefore operators are usually unaware that they are losing targets due to low-level interference. Interference can cause the loss of targets at any range. Low interference thresholds for communication-type signals, insidious behavior of target losses, and potential loss of targets at any range all combine to make low-level interference to radar receivers a very serious problem.

Keywords: radar interference; radar interference vulnerability; radar performance degradation; radar target loss; radar target detection; RF interference; UWB interference effects

• Report (8.3 MB)

• Contents, List of Figures, List of Tables, Abbreviations/Acronyms

• Executive Summary

• Report Body, excluding appendices (6 MB)

• Chapters 1 – 4
  
  
  • Chapter 1: Radar Fundamentals Related to Interference Testing and Measurements
  • Chapter 2: Setting Conditions for Interference Measurements on Radar Receivers
  • Chapter 3: Interference Measurements on Long-Range Air Search Radars
  • Chapter 4: Interference Measurements on Short-Range Air Search
    
    
• Chapters 5 – 9
  
  
  • Chapter 5: Interference Measurements on a Fixed Ground-Based Meteorological Radar
  • Chapter 6: Interference Measurements on Maritime Radionavigation Radars
  • Chapter 7: Interference Measurements on an Airborne Meteorological Radar
  • Chapter 8: Summary of Interference Effects on Radars
  • Chapter 9: References
    
    
• Appendices
  
  
  • Appendix A: Example Interference Rejection (IR) Responses of a Maritime Radionavigation Radar
  • Appendix B: Selected Interference Emission Spectra
  • Appendix C: Calibration of Undesired Signals and Examples of Radar IF Selectivity Curves
  • Appendix D: Test Results Illustrating the Effective Duty Cycle of FM-Pulshed Waveforms in a Marine Radar Receiver

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:
Margaret Luebs, Publications Officer
Institute for Telecommunication Sciences
Voice: (303) 497-3572
info@its.bldrdoc.gov

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