1

U.S. STUDY RADAR EMISSION MASKS

A Review of the Radar Spectrum Engineering Criteria (RSEC)

ROBERT L. HINKLE

United States Department of CommerceNational 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 RSECEmission bandwidth (40 dB)

Emission levels

Tunability

Antenna patterns

Frequency tolerance

Receiver selectivity

Image and spurious rejection

Local-oscillator radiation

4

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)

5

REVIEW OF RSEC

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

6

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.

7

-100

-75

-50

-25

0

25

3600 3700 3800 3900 4000 4100 4200

B(-40 dB) = 25.3 MHzBn(-20 dB) = 7.3 MHz

w/ Filter

w/o Filter

RSEC-C

(S = 20)

Run Time: 5/21/98

80 dB Floor Level Scenario

(S = 40) Scenario

B (-40 dB) Mask

Bn (-20 dB) Mask Scenario

*Note: Assumptions gathered from data sheets rather than SPS Submission.

Non-FM Pulse RadarCriteria C category w/ 80 dB Floor (override)Pp = 89.29 dBm (850 kW)*t = 0.6s*tr = 0.1 s*PRR = 1125 PPS *Coaxial Magnetron Tube Type (w/ & w/o Filter)

Frequency, MHz

Rec

eive

d S

igna

l Lev

el, d

Bm

RADIONAVIGATION RADAR(Coaxial Magnetron W/WO Filter)

8

RADIONAVIGATION RADAR(Coaxial Magnetron)

AN/SPS-64(V)

-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=17.324, P G=0., Bn(-20)=5.66, B(-40)=24.033, S=20., X(dB)=60.

9

WEATHER RADAR(Klystron output Device)

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.

10

OVERRVIEW OFRSEC CHANGES BEING CONSIDEERED

Add the following to Group A (Exempt from RSEC).

Maritime Radionavigation 2900-3100 MHz

Aeronautical Radionavigation and Radionavigation 5350-5470 MHz

Aeronautical Radionavigation 15.4-15.7 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) + 30Where: 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) + 30Where: 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.