Development of Microwaveof Microwave Brightness Temperature … · Rdi tadiometers MHz, 60 MHz, . onlyyp up to 12.4 GHz: 12.4 GHz ... currently expanding to 110 GHz (Could be up graded

DevelopmentDevelopment Brightness Tempe

t Nat N

Dave Walker, Jim RanDazhen Gu, Katie MacR

ElectromagneNIST-B

NOAA/NESDIS Workshopfrom Satellite Microwave

of Microwaveof Microwave erature Standards

NISTNIST

da, Chriss Grosvenor, Reynolds, Amanda Cox,

etics DivisionBoulder

Electromagnetics Divisionp on Climate Data Records e Radiometry, 22 Mar 10

OUT

Hi t d B k d• History and Background• Previous Activities

C t A ti iti• Current Activities– Standard Radiome

F• Free space r• Identifying an

St d d T t– Standard Target • Target chara• Materials me

• Additional Capabilitiesp

LINE

dd

eterdi t i tadiometric measurements

nd quantifying error sources

cterizationeasurements

Electromagnetics Division

Traceability—FoundMMeasur

Property of the result of value of a standard wherstated references, usuallyinternational standards tinternational standards, tchain of comparisons all

t i tiuncertainties

(

dation for Accurate trements

a measurement or the reby it can be related to yy national or through an unbrokenthrough an unbroken having stated

Based on the SI International System of Units)

Electromagnetics Division3

NIST N i RNIST Noise R

• Coaxial radiometers: 301 – 18 GHz• N.B. Coaxial primary stdp y

• Waveguide radiometers18 – 26 5 26 5 – 40 3318 26.5, 26.5 40, 33• Each waveguide radiom

reflectometer & heterodreflectometer & heterod

R di tRadiometers

0 MHz, 60 MHz,

d. only up to 12.4 GHzy ps: 12.4 GHz – 18 GHz, 3 – 50 50 – 65 GHz3 50, 50 65 GHz.

meter contains a full 6-port yne receiveryne receiver



Thermal Noise Pr• Ambient & cryogenic (liqAmbient & cryogenic (liq

standards.

uTCry ≈ 0.65

◄Coaxial

Waveguide►

uTAmb ≈ 0.1

rimary Standardsquid nitrogen)quid nitrogen)

5 K

K


HistHistProgram to support micginitiated in 2001

− Arose out of historArose out of historNoise Project with

− Program ran until 2og a a u tlack of funding

Current program resurrCurrent program resurr− Funded through C

Change InitiativeChange Initiative− Essentially picked

torytorycrowave remote sensing g

rical Microwave Thermalrical Microwave Thermal 30+ years’ experience2005, then canceled due to 005, t e ca ce ed due to

rected in June 2009rected in June 2009Congressional Climate

up where we left off


PreviousPrevious

Concept for brightness te• Concept for brightness te• Standard Radiometer• Standard Target

Antenna Pattern Charact• Antenna Pattern Charact• Target Characterization

• Absorber meas. in WR

Reflectivity measurem• Reflectivity measurem

• Infrared imaging

ActivitiesActivities

emperature standardemperature standard

terizationterization

R-90 (8-12.4 GHz) waveguide

mentsments


Previous ActivPrevious Activ

N bi t i TNear-ambient noise T mRadiometer free space pModeling of target proxD t t li itDetector nonlinearityStandard Terminology gyMeasurement of noise for Aquarius instrumentfor Aquarius instrument

vities (cont'd)vities (cont d)

tmeasurementsmeasurements

ximity effects

Projectjdiode calibration sources tt


Microwave Remote

Important question: w

TargetBrightness

T t

Anpa

PhysicalTemperature

TemperatureIncident

BrightnesTemperatuTemperatu

Cal Target

Want as much as posComplications:p– conditions & environme– absolute vs relative “ac– absolute vs. relative ac

e-Sensing Metrology

hat quantity is traceable?

IF

ntennaattern

Internal V’sor P’s

ReceiverIF,

Processing,etc.ss

ureNoise Temp,

Li iure Linearity

sible included.

entccuracy” (uncertainty)


ccuracy (uncertainty)

Brightness TBrightness TemperatuFramework for standardFramework for standard

C T η=

Rad.

Cryo

Amb

MinAT , η=

∫Std.Ant.

TA, out

0TB= TA, in

∫

∫=

π

η

4

maiM

outA TT , α=

Temperatureure:d radiometersd radiometers

TT )1( η+ SLMML TT )1( η−+

Ωφθ )( dF),(),(∫

mainnB dFT

TΩφθφθ

Ωφθ

Ωφθ

),(

),(

dF

dF

n

inn

)()(

),(

∫

∫=

mainn

mainML

dFT

dFT

Ωφθφθ

Ωφθ

.),(

),(),(

∫

∫=

othern

othernB

SLdF

dFTT

Ωφθ

Ωφθφθ

ainA TT )1(, α−+


L/1≈α

UncertaintiesMLT

Ta : ∼ 0.2 KTA, out : ∼ 0.3 – 0.5 K,α : ∼ 0.5 %ηM : ??

If uη ~ uα , then at 20 GHz the 0.3 K – 0.8 K for TB between 2

So plan to develop stanSo, plan to develop stan18 – 26 GHz, 26.5 – 4

( )aoutAaL TTT −+= ,1 ( )aout

Ma ,αη

uncertainty in is 200 K & 300 K.

MLT

ndard radio-meters forndard radio meters for 40 GHz, & 50 – 65 GHz.


Millimeter Wave Pla

Frequency Range - 1 to 75 GHzcurrently expanding to 110 GHz

(Could be up graded to 220+ GHz

Typical Uncertainties:

(Could be up graded to 220+ GHzUsing NIST probe position errorcorrection software and RF Equipment)

yp

1 - 26 GHzgain ± 0.20 dBpatterns ± 0.05 dB/dB to -40 dB

26 - 50 GHzgain ± 0.25 dBpatterns ± 0.07 dB/dB to -40 dB

50 75 GHz50 - 75 GHzgain ± 0.30 dBpatterns ± 0.10 dB/dB to -40 dB

nar Near-field Rangeg


WR-42 StandaWR-42 Standa

Measured antenna patteMeasured antenna pattehorn (SGH) on the ne

rd gain hornrd gain horn

ern for a standard gainern for a standard-gain ar-field range.



Target reflecg

0.2

0.15

|

0 05

0.1|ΔΓ

0

0.05

ctivity effectsy

AIMR AntennaAIMR target, with cover

34 - 35 cm, 37 GHz

0 1 2 3 4 5 6 7 8 9 10Cart Position (mm)


IR Thermal ImIR Thermal Immage of Targetmage of Target


Noise Temperature Mea

Don’t normally measure neCheck of uncertainty near

Designed & built variable soDesigned & built variable sotemperature.

Measured it.

Tests entire system(except antenna)(e cept a te a)

asurements Near Ambient

ear ambient.ambient:ource with known noiseource with known noise


0.02

0.015Typical Type BWR-42 System

unce

rtain

ty

0.01

Frac

tiona

l u

0.005

0 1000 2000

0

0 1000 2000

B Uncertaintym, 20 GHz

3000 4000 5000


3000 4000 5000T(K)

Noise measurem

0.8

1

NFRad (Coaxial Radi

0.4

0.6

K)

8 GHz

0

0.2

.

Pred

icte

d (K

0 4

-0.2

0

Mea

sure

d - P

0 8

-0.6

-0.4M

260 270 280 290

-1

-0.8

60 70 80 90T

ents near ambient

iometer)

300 310 320 330


300 3 0 3 0 330T(K)

Radiometric TargRadiometric Targ--Use existing NIST radionoise standards:

CryC

CryCryC

Rad. Am

C

aRad. AmAm

C

a

StdA t

a

x

0StdA t

a

x

0

NIST Noise Radiometer + Characte

Antx Antx

get Measurementget Measurementometer linked to primary

yoyoyo

mbmbmb

.t

Target.t

TargetTarget

erized Antenna

t.t.


Standard radiometer w(NASA GSFC “Cry

with typical cal targetyo” target shown)



Radiometric TargRadiometric Targ(NOAA GS

360

350

360

K)

He

330

340

empe

ratu

re (K

320

Brig

htne

ss T

e

From targeMeasuredFrom targe

300

310

Targ

et

0 50 100 150 200 250Distance

290

Ambient

DistanceMeasured & predicted brightness temperatures vs

get Measurementget MeasurementSR target)

ated target

et temperature (e = 0.99)(error bars are std. unc., uc)et temperature (e = 0.98)

300 350 400 450 500(cm)

target


(cm)s. separation distance.

Alternative: StAlternative: St

AIMR Target

andard Targetandard Target

GSFC “Cryo” Target


Proposed ComRadiometer

I d d t li tiIndependent realizations oIndependent, full uncertainCombined (full) standard wof the two

− Possible √2 uncertain

Transfering the TB standarg B

− A second (portable) tstandard

− Measuring a customewith the full standard

bined Standardr and Target

f Tof TB

nty analyseswould be a weighted average

nty improvement vs. single std.

rd would involve either:target calibrated with the full

er’s target or radiometer at NIST


Detector nonliDetector nonli

0.45T = 10 °CT = 30 °CT = 20 °C

ZL

0 43mV/μW

)

0.43

nsiti

vity

(m

0.41

Se

0.390.1 10.1 1

Input P

inearity studyinearity study

= 125 Ω

10


10

ower (μW)

St d d tStandard termmicrowavemicrowave

(a.k.a. “Diction

Developed in cooperation(W ki G C l(Working Group on Cal-

Link (including all relevan( ghttp://www.nist.gov/eeel/e

ronics/noise project cfmronics/noise_project.cfm

i l fminology forradiometryradiometrynary Project”)

n with CEOS WGCV V l)-Val)t publications) at:p )

electromagnetics/rf_electmm


Current ACurrent A

R fl ti it MReflectivity Measureme− 2 horns, 3 targets,− Additional absorbe

Expanded RadiometerExpanded Radiometer Measurements

Additional horns a− Additional horns a− Better alignment (

transit)transit)


tents, 2 temperatureser materialsFree-SpaceFree Space

and targetsand targetsfixturing and surveyor’s


Current ACurrent A

Ab b• Absorber measuremen• Three WG bands (WR -9

• Fixturing up to WR-10

• Five concentrations of fe

• Plans for measuring cast

• Free-space absorber m• Multiple absorber samples

• Ensemble detection ex


t i idts in waveguide90, 62, 42)

errous-doped epoxy (machinable)

table material

measurementss

periments with GSFC


MIR Calibration Targets (Coourtesy P. Racette, GSFC)


Radiometer MMeasur

/ Reflectivity trements


Reflectivity MeasurementsC i l dConical and Pyramidal Standard G i HGain HornsVector Network AnalyzerMultiple Horn-to-Multiple Horn totarget distancesAmbient & heatedAmbient & heatedNext: full emissivity


GSFC “Cryoo” target |Γ|


GSFC “Cryoo” target |Γ|


GSFC “Cryo” tarrget: flat plate |Γ|


Radiometric setuup – GSFC target


Target AbsorberTarget Absorber

I idIn waveguide− Measuring perm

frequencies bey− Discovered batc

sample set− Plans to measu

Free spaceMeasurement te− Measurement te

− Several sample

r Measurementsr Measurements

meability and permittivity for yond those provided by mfr.ch-to-batch variation in one

ure castable material

echnique verifiedechnique verifiedes obtained for testing


Permittivity M(showing batch-to

Measurements o-batch variation)


Additional CAdditional C

C l bilit dComplex permeability andmaterials (in waveguide)

S lid ( i t− Solids (e.g., moist so− Liquids (e.g., salt wat

G (− Gasses (e.g., greenh

Noise diode and cold-FETh t i ti (T t bilitcharacterization (T; stabilit

Detector nonlinearityAntenna characterization (field pattern transformation

CapabilitiesCapabilities

itti it f permittivity of many

il)oil)ter)

)house gases)

T internal cal source t )ty)

(pattern, gain, near-to-far-n)


SummThe need for a national (i.e

standard is being recognstandard is being recognthe remote-sensing com

S b t ti l dSubstantial progress made“foundational” aspects o

Propose a combined standPotential reduction in uncertaintyProvides a means for checking a

Initial development would extend up to 65 GHz

Working on special test cho g o spec a test c

maryye., SI-based) TBnized and accepted innized and accepted in

mmunityt NIST ie at NIST on various

of a TB standarddard radiometer+target

ynd transfer

be 18-26.5 GHz band;

hamber…Electromagnetics Division

a be

Next: Special tes

Temperature MonitoringElectronics

Ambient

WaveguideRadiometer

Ambient Noise

Standard

Horn

Waveguide Switch

CryogenicNoise

Standard

st chamberTemperature Sensors

MountingPlate

Absorber

Housing

Ai Ci l

n

Air Circulator

Target

Temperature Control

Air circulator

pAnd Alignment Systems


SummSummDevelopment of a microDevelopment of a microtemperature standard isNIST h l i lNIST has multiple capaand post-launch cal/valOther support tests andavailable in the interimYour input and suggest

“Th b tt d t“The better you understathe easier it is to analyzetransfer function” –D Kutransfer function D. Ku

marymaryowave brightnessowave brightness s non-trivialbili iabilities to support pre-efforts

d collaborations are

tions are welcomedd th t f th tand the parts of the system,

e (or re-analyze) the system unkee


unkee

Documents

Development of Microwaveof Microwave Brightness Temperature … · Rdi tadiometers MHz, 60 MHz, . onlyyp up to 12.4 GHz: 12.4 GHz ... currently expanding to 110 GHz (Could be up graded