Multifunction Phased Array Radar Advanced Technology Demonstrator David Conway Sponsors: Mike Emanuel, FAA ANG-C63 Kurt Hondl, NSSL
Multifunction Phased Array Radar (MPAR) for Aircraft and Weather Surveillance Current Aircraft and Weather Radars Terminal Area Aircraft ASR-8 ASR-9 ASR-11 Multifunction Phased Array Radar Long Range Aircraft ARSR-1/2 ARSR-3 ARSR-4 FPS-20/66/67 Long Range Terminal Area Weather Weather NEXRAD TDWR 9 Radar System Designs Rotating Dish Technology Many Nearing End-of-Life Lower Life Cycle Cost Reduced radar count from > 600 to 400 Lower O&M (no moving parts) Streamlined training and sparing infrastructure Increased performance benefits Adaptive Scan Strategies Higher sample rates MPAR ATD - 2
MPAR ATD - 3 Adaptive Beam Scanning
Phased Array Advantages for Weather Sensing Slow Update Rate Tornado Track 4 minute Updates (e.g. NEXRAD Rate) Fast Update Rate 1 minute Updates (e.g. MPAR Requirement) Set-Up Two forecasting teams presented video clips from data set Clips differed by the update rate o 4 min for NEXRAD o 1 min for MPAR Result Median difference in tornado declaration time ~ 20 minutes earlier for the higher sample rate loop MPAR ATD - 4
Design Concept Aircraft Surveillance Two 6 x 2 beam clusters Aircraft (up to 24 linear pol beams) Weather Surveillance Panel-based Aperture Polarization Diverse for Weather Multiple Beams for Timeline Frequency: S-Band (2.7 3.1 GHz) Diameter: 4m & 8m T/R Modules/Face: 5,000 / 20,000 Beamwidth: 2 / 1 Bandwidth: Peak power: Polarization: Weather (1 dual pol beam) Array cost/m 2 : $60K / m 2 5 MHz 16 W / element Dual linear/circular EASY HARD Key Challenge: Reduce array cost from current $1M / m 2 to $60K / m 2 MPAR ATD - 5 T/R = Transmit / Receive
Development Timeline First Panel 2 Panel Subarray 10 Panel Demonstrator 76 Panel Advanced Technology Demonstrator Gen1 Panel Gen2 Panels Performance Assessment MPAR ATD FY 07-11 FY 12-13 FY 13-15 FY15-18 T/R Module and Aperture Printed Circuit Board (PCB) Assembly development Custom integrated Circuit (IC) chip set development Component respin Tileable Backplane design Thermal Design Range testing Polarimetric Performance Digital beam clusters Verify thermal management Initial radar testing Terminal MPAR Size, 4m Real time radar backend Aircraft/ Weather Processing Specification Development MPAR ATD - 6
Gen1 Aperture PCB Assembly Critical Technologies Dual Polarized Balance feed Stacked Patch Overlapped Digital Subarray Beamformer 16 Heat Sink Top View Bottom View Fully populated 64 element Aperture PCB Assembly Dual simultaneous polarization 2.7 2.9 GHz operating band Transmit and receive functionality Dual Pol, 6W/Pol T/R Module < $25 at volume MPAR ATD - 7 PCB = Printed Circuit Board T/R = Transmit / Receive
Development Timeline First Panel 2 Panel Subarray 10 Panel Demonstrator 76 Panel Advanced Technology Demonstrator Gen1 Panel Gen2 Panels Performance Assessment MPAR ATD FY 07-11 FY 12-13 FY 13-15 FY15-18 T/R Module and Aperture Printed Circuit Board (PCB) Assembly development Custom integrated Circuit (IC) chip set development Component respin Tileable Backplane design Thermal Design Range testing Polarimetric Performance Digital beam clusters Verify thermal management Initial radar testing Terminal MPAR Size, 4m Real time radar backend Aircraft/ Weather Processing Specification Development Initial cost/ performance data MPAR ATD - 8
MPAR Panel Aperture PCB T/R Modules Standoffs DC/Logic Interconnects Backplane PCB Tx Driver Panel Structure Air Flow MPAR ATD - 9
Ten Panel Demonstrator System Components / Set-up for String Testing on Hanscom Runway String Testing of 10 Panel Demo MPAR ATD - 10
Polarimetric Radar Measurements Birdbath Mode Looking up, rain drops are always round! Bright Band MPAR ATD - 11
Development Timeline First Panel 2 Panel Subarray 10 Panel Demonstrator 76 Panel Advanced Technology Demonstrator (ATD) Gen1 Panel Gen2 Panels Performance Assessment MPAR ATD FY 07-11 FY 12-13 FY 13-15 FY15-18 T/R Module and Aperture Printed Circuit Board (PCB) Assembly development Custom integrated Circuit (IC) chip set development Component respin Tileable Backplane design Thermal Design Range testing Polarimetric Performance Digital beam clusters Verify thermal management Initial radar testing Terminal MPAR Size, 4m Real time radar backend Aircraft/ Weather Processing Specification Development Initial cost/ performance data MPAR ATD - 12
Advanced Technology Demonstrator (ATD) 4 m National Weather Radar Testbed (NWRT) Norman, OK 4,864 element array (76 Panels) 58 kw peak radiated power 2.7-3.1 GHz Dual polarization 48 digital receiver channels Real time processing Shipment to NSSL February 2018 MPAR ATD - 13
Radar Testbed Interior Layout Antenna Array 48VDC Rectifier Banks Radar Backend: Receivers, Exciters, Digital Signal Processing (DSP) Pedestal and Elevation rotator Beam-Steering Generator (Array Control Computer) Azimuth Rotary Platform System Power HVAC Application Software MPAR ATD - 14 MIT-LL Lead
ATD Assembly, Integration, and Test Antenna Frame Alignment Cable/ Beamformer Fab & Test Install Cables/ Beamformers Install Panels Antenna Testing (Phase 1) Radar Testing (Phase 2) Backplane Testing Panel Testing Integrate Backend Electronics MPAR ATD - 15
Array Installation in Nearfield Chamber MPAR ATD - 16
First ATD Tests: Element Health Check Each element measured one at a time using remote probe Measurement time for all elements, all modes: <30 minutes Array Viewed from Non-Radiating Side Tests repeated roughly once per day. Remote probe MPAR ATD - 17
Reference State Data Collect Nearfield probe moves directly in front of element-under-test Rx Ref. State Amplitude Insertion gain and phase measured for each element in the array at its reference state Data used for precision electrical alignment of all elements in the array Rx Ref. State Phase MPAR ATD - 18
Nearfield-to-Farfield Transform (NF2FF) Raw NF scan data is on a regular 2-D grid plane (physical space) Data is transformed to Farfield pattern using FFT-based process NF2FF Antenna FF Pattern is adjusted using waveguide probe calibration dataset ( Probe Compensation ) MPAR ATD - 19 NF = Nearfield FF = Farfield FFT = Fast Fourier Transform
Next Steps Delivery Disassembly of system Shipment to NSSL Installation on site Integration and Test Calibration and alignment Design Verification Test Initial Operational Capability Operation Polarimetric radar calibration Weather Severe storm science MPAR ATD - 20
Summary MIT Lincoln Laboratory is developing, building, testing and fielding a 4-meter S-band dual-polarization active phased array antenna The MPAR ATD is the culmination of work sponsored by the FAA and NOAA since FY 2007 on low-cost active phased array technology ATD development has informed FAA investment decisions for Next Generation primary aircraft surveillance The ATD will serve as the primary weather research asset for the National Severe Storms Laboratory in Norman, Oklahoma MPAR ATD - 21
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