# Presentation: 743759

## 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

**Notes:**
ZDR: Requires > 20 dB cross-pol isolation over scan range of interest, as well as well matched H and V beam patterns over scan range of interest.. C through X sensitivity, attenuation and resolution trade-offs.  ZDR requires > 20 dB cross-pol isolation  over scan sectors from boresight.  Sur. C abability

##  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

- 11/1/06

## 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

- 11/1/06

**Notes:**
Gave up formation of simultaneous, multiple pencil beams due to excessive cost.

## 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 |

- 11/1/06

**Notes:**
Take slide and add ground based, wide-band. Delete X, and C band.  3 KW peak power at X-band

## 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 |

- 11/1/06

**Notes:**
Hybrid less integrated highr wt. more cooling needs

## 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

- 11/1/06

**Notes:**
Check 9 dB vs 6 dB gain

## 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?

- 11/1/06