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RADAR SPECTRUM ENGINEERING CRITERIA(RSEC)

A Comprehensive Review

ROBERT L. HINKLE

Alion Science and Technology185 Admiral Cochrane Drive

Annapolis, MD 21401

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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.

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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

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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.

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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

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RSEC EMISSION MASK

-100

-80

-60

-40

-20

0

20

-150 -100 -50 0 50 100 150

Criteria D

Criteria C

Criteria B

t = 1.0 s

tr = 0.05 s

PRR = 1000 PPS Average

Pp = 90 dBm (1 MW)

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AIRPORT SURVEILLANCE RADAR(Klystron Output device)

ASR-8 (Channel A)

-120

-100

-80

-60

-40

-20

0

20

2550 2650 2750 2850 2950 3050 3150 3250 3350

Frequency, MHz

Rec

eive

d P

ow

er N

orm

aliz

ed t

o M

axim

um

(d

B)

Data

Mask 1

Mask 1: , t=0.6, tr=0.05, Bc=NA, d=NA, Bc=NA, N=1, P RR=1040, FL=NA, FH=NA, Bs=0, P t=27.195, P G=0., Bn(-20)=10.335, B(-40)=35.796, S=40., X(dB)=80.

(radiated measurement in far field of antenna)

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NEXRAD Radar

-120

-100

-80

-60

-40

-20

0

20

2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 7000

Frequency, MHz

Rec

eive

d P

ow

er N

orm

aliz

ed t

o M

axim

um

(d

B)

Data

Mask 1

Mask 1: , t=1.6, tr=0.1, Bc=NA, d=NA, Bc=NA, N=1, P RR=1304, FL=NA, FH=NA, Bs=0, P t=35.235, P G=0., Bn(-20)=4.144, B(-40)=15.5, S=40., X(dB)=80.

WEATHER RADAR(Klystron output Device)

(radiated measurement in far field of antenna)

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RADIONAVIGATION RADAR (Coaxial Magnetron WO Filter)

Radionavigation Radar without Filter

-120

-100

-80

-60

-40

-20

0

20

3600 3700 3800 3900 4000 4100 4200

Frequency, MHz

Receiv

ed

Po

wer

No

rmali

zed

to

Maxim

um

(d

B)

Data

Mask 1

Mask 2

Mask 2: , t=0.6, tr=0.1, Bc=NA, d=NA, Bc=NA, N=1, P RR=1125, FL=NA, FH=NA, Bs=0, P t=25.369, P G=0., Bn(-20)=7.308, B(-40)=25.311, S=30., X(dB)=80.

(radiated measurement in far field of antenna)

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Radionavigation Radar with Filter

-120

-100

-80

-60

-40

-20

0

20

3600 3700 3800 3900 4000 4100 4200

Frequency, MHz

Rec

eive

d P

ow

er N

orm

aliz

ed t

o M

axim

um

(d

B)

Data

Mask 1

Mask 2

Mask 1: , t=0.6, tr=0.1, Bc=NA, d=NA, Bc=NA, N=1, P RR=1125, FL=NA, FH=NA, Bs=0, P t=25.369, P G=0., Bn(-20)=7.308, B(-40)=25.311, S=20., X(dB)=80.

RADIONAVIGATION RADAR(Coaxial Magnetron With Filter)

(radiated measurement in far field of antenna)

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RADIONAVIGATION RADAR(Coaxial Magnetron, Slotted Array Antenna)

Maritime Radionavigation Radar

-140

-120

-100

-80

-60

-40

-20

0

20

2150 2650 3150 3650 4150 4650 5150 5650 6150

Frequency, MHz

Rec

eive

d P

ow

er N

orm

aliz

ed t

o M

axim

um

(d

B)

Data

Mask 1

Mask 2

Mask 1: , t=1, tr=0.1, Bc=NA, d=NA, Bc=NA, N=1, P RR=900, FL=NA, FH=NA, Bs=0, P t=28.836, P G=0., Bn(-20)=5.66, B(-40)=19.606, S=20., X(dB)=60.

(radiated measurement in far field of antenna)

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OVERVIEW OFRSEC 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.

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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) + 30Where: 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).

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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) + 30Where: 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).

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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

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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