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

10/12/20072 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, σ v ) 2x resolution of current system – using agile scanning Dual polarization H,V linear – Z H, Z DR, K DP, RHO HV

10/12/20073 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

10/12/20074 PAR Characteristics OptionsBeamwidth ( θ h x θ v ) Sensitivity 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) Z H,Z DR,K DP, RHO HV 11, (X) 130 (C) Wide-Band Ground Based 0.6° x 1.0° (X) 1.0° x 1.6° (C) -19 (X) -11 (C) Z H,Z DR,K DP, RHO HV 23,128N/A ELDORA1.8° x 2.0°-11ZHZH N/A300

10/12/20075 Hybrid Vs Integrated MMIC AttributesHybridIntegrated Peak power~ 1 to 3 Watts~ 0.2 to.5 Watts WeightHeavy ~Light ~ CoolingLiquid or forced air cooling Forced air cooling is sufficient CostModerate R&D costHigh R&D cost

10/12/20076 Relative Comparison between X and C-bands ParameterComment Clear air sensingDetectability at X-band is 9 dB greater than at C-band DopplerResolution increases with frequency Attenuation in rainC-band: 0.07 dB/km; X-band: 0.42 dB/km for 30 mm/hr Rayleigh scattering gainDetectability at X-band is 9 dB greater than at C-band

10/12/20077 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?