RADAR SPECTRUM ENGINEERING CRITERIA (RSEC) A Comprehensive Review ROBERT L. HINKLE Alion Science and Technology 185 Admiral Cochrane Drive Annapolis, MD 21401

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.

● Last major review of RSEC conducted in 1973-1977 time frame REASON FOR RSEC REVIEW ● Last major review of RSEC conducted in 1973-1977 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

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, filters 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. This coordination is in progress.

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

RSEC EMISSION MASK

AIRPORT SURVEILLANCE RADAR (Klystron Output device) (radiated measurement in far field of antenna)

WEATHER RADAR (Klystron output Device) (radiated measurement in far field of antenna)

RADIONAVIGATION RADAR (Coaxial Magnetron WO Filter) (radiated measurement in far field of antenna)

RADIONAVIGATION RADAR (Coaxial Magnetron With Filter) (radiated measurement in far field of antenna)

RADIONAVIGATION RADAR (Coaxial Magnetron, Slotted Array Antenna) (radiated measurement in far field of antenna)

OVERVIEW OF RSEC CHANGES BEING CONSIDERED ● Add the following to Group A (Exempt from RSEC).  Maritime Radionavigation 2900-3100 MHz  Radionavigation 5460-5650 MHz  Aeronautical Radionavigation 15.4-15.7 GHz These radars are, for the most part, not under Government control and are widely used by the private sector.

RSEC CHANGES BEING CONSIDERED 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  Propose to change X (dB) floor level to: X (dB) =10LogP(Watts) + 30 Where: 60 dB ≤ X (dB) ≤ 80 dB Current RSEC (X) level is dependent on the power, pulse width, and prf of the radar (see section 5.5.2 of NTIA Manual of Regulations & Procedures for Federal Radio Frequency Management).

RSEC CHANGES BEING CONSIDERED 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  Propose to 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 Current RSEC (X) level is dependent on the power, pulse width, and prf of the radar (see section 5.5.3 of NTIA Manual of Regulations & Procedures for Federal Radio Frequency Management).

RSEC CHANGES BEING CONSIDERED 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 filters ● Group E (Criteria E)  No proposed changes

RELATED ITU-R ACTIVITIES Proposed Formation of JRG 1A/1C/8B Rec. ITU-R SM.1541: Out-of-Band emissions Rec. ITU-R M.1314: Methods to reduce radar unwanted emissions Recommendation ITU-R M.1177: Techniques for measurement of radar unwanted emissions 