Phased Array Radar Configurations for Ground-Based and Airborne

Deployments

Dual Use: Deployable on airborne and ground-based platforms

Key measurements: — 2-D winds and polarization variables for kinematics and microphysics— Uncertainty in precipitation estimation : 40% for reflectivity; 15% for

polarization

Key technological challenges:— Design of light weight AESA elements that can be operated

with passive or modest forced air cooling— Dual-pol performance - accurate measurement of Zdr ~ 0.1

dB— Wide-bandwidth - operations at C through X-bands

Univ. Community involvement: Cutting edge defense technology accessible to University community for scientific and technological applications

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Configurations -- Airborne

• Four active element scanning array (AESA) quasi- conformal antennas– Two side-looking; top, bottom looking

• Sequential aft and fore beams in azimuth for dual-Doppler wind retrieval; electronic scanning in elevation plane for compete 3D winds

• Composite “surveillance” scan ~ situational awareness near severe weather

• Dual Doppler (V, σv)• 2x resolution of current system – using agile scanning• Dual polarization H,V linear

– ZH, ZDR, KDP, RHOHV

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Configurations – Ground Based

• Re-package airborne system into two rapidly scanning mobile truck-based Radars– Combine pairs of AESA’s into single flat aperture

(for improved sensitivity and beamwidth)– Electronic scanning in elevation and electronic and

mechanical scanning in azimuth• Dual polarization H,V linear• Multiple receive beams for radial and transverse

wind estimation

Rapid DOW; Courtesy CSWR

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PAR Characteristics

Options Beamwidth

(θh x θv)

Sensitivity dBZ @ 10

km

Co-Polar Variables

# Elements

Along Track

Res. (m)

Wide-Band (X,C) Dual-Pol

1.2° x 1.0° (X)2.0° x 1.6° (C)

-13 (X)-5 (C)

ZH,ZDR,KDP, RHOHV

11,564 150 (X) 130 (C)

Wide-Band Ground Based

0.6° x 1.0° (X)1.0° x 1.6° (C)

-19 (X)-11 (C)

ZH,ZDR,KDP, RHOHV

23,128 N/A

ELDORA 1.8° x 2.0° -11 ZH N/A 300

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Hybrid Vs Integrated MMIC

Attributes Hybrid Integrated

Peak power ~ 1 to 3 Watts ~ 0.2 to .5 Watts

Weight Heavy ~ Light ~

Cooling Liquid or forced air cooling

Forced air cooling is sufficient

Cost Moderate R&D cost High R&D cost

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Relative Comparison between X and C-bands

Parameter Comment

Clear air sensing Detectability at X-band is 9 dB greater than at C-

band

Doppler Resolution increases with frequency

Attenuation in rain C-band: 0.07 dB/km; X-band: 0.42 dB/km for 30

mm/hr

Rayleigh scattering gain Detectability at X-band is 9 dB greater than at C-

band

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Challenges for PAR Developers

• In what ways University community can play an active role in developing affordable AESA radar ?

• Will it be possible to achieve necessary polarization purity at angles away from bore sight?

• Do hurricane reconnaissance missions benefit from airborne weather radar observations?

• How does a next generation space-borne weather radar benefit from PAR efforts?