1 U.S. STUDY RADAR EMISSION MASKS A Review of the Radar Spectrum Engineering Criteria (RSEC) ROBERT L. HINKLE United States Department of Commerce National Telecommunications and Information Administration Office of Spectrum Management

2 PURPOSE Ensure an acceptable degree of electromagnetic compatibility among radar systems, and between such systems and those of other radio services sharing the frequency spectrum. Promote efficient use of the spectrum.

3 RADAR CHARACTERISTICS ADDRESSED IN THE RSEC Emission bandwidth (40 dB) Emission levels Tunability Antenna patterns Frequency tolerance Receiver selectivity Image and spurious rejection Local-oscillator radiation

4 RSEC EMISSION MASK

5 REVIEW OF RSEC Last major review of RSEC conducted in time frame New generation of radar systems more complex  Waveform characteristics change pulse-to-pulse  Dynamic PRF pulse trains Trend toward solid state output devices Increase in interference from radars ITU-R Working Party 8B (Radiodetermination) has set up a radar group to investigate feasibility of more stringent emission masks than contained in ITU-R Recommendation SM1541, Annex 8, by 2006 Radiocommunication Assembly meeting.  Work Program developed by ITU-R Working Party 8B

6 AIRPORT SURVEILLANCE RADAR (Klystron Output device)

7 RADIONAVIGATION RADAR (Coaxial Magnetron W/WO Filter)

8 RADIONAVIGATION RADAR (Coaxial Magnetron)

9 WEATHER RADAR (Klystron output Device)

10 OVERRVIEW OF RSEC CHANGES BEING CONSIDEERED Add the following to Group A (Exempt from RSEC).  Maritime Radionavigation MHz  Aeronautical Radionavigation and Radionavigation MHz  Aeronautical Radionavigation GHz

11 OVERVIEW OF RSEC CHANGES BEING CONSIDERED Group B (Criteria B)  Retain 40 dB bandwidth formulas  Assess feasibility of roll-off slopes of 30/40 dB per decade  Change X (dB) Level to 60 dB for near term, and consider phasing in X (dB) floor of: X (dB) =10LogP(Watts) + 30 Where: 60 dB ≤ X (dB) ≤ 80 dB

12 OVERVIEW OF RSEC CHANGES BEING CONSIDERED Group C (Criteria C)  Retain 40 dB bandwidth formulas  Assess feasibility of roll-off slopes of 30/40 dB per decade  Change X (dB) Level to 60 dB for near term, and consider phasing in X (dB) floor of: X (dB) =10LogP(Watts) + 30 Where: 60 dB ≤ X (dB) ≤ 80 dB

13 OVERVIEW OF RSEC CHANGES BEING CONSIDERED Group D (Criteria D)  Retain all of Criteria D except change harmonic levels to 80 dB  New solid state radars can not meet Criteria D without waveguide filter Group E (Criteria E)  No proposed changes

14 APPROACH  Develop a software program that will provide current and optional emission masks.  Identify, through measurements, emission characteristic of radars with various types of output devices and antennas.  Apply software program (emission masks) to measured emission characteristics to assess feasibility of establishing a more spectrum efficient emission mask.  Engage the radar manufacturers and radar output device manufacturers to identify state-of-the-art capabilities.  Through the IRAC/TSC, in coordination with Federal agencies reach agreement regarding draft revised emission masks for future radar systems.