The document summarizes the past, present, and future of HIRAD (Hurricane Imaging Radiometer), which aims to provide high-resolution microwave measurements of hurricanes from an airborne platform. It describes the early work using SFMR (Stepped Frequency Microwave Radiometer) in the 1980s that inspired HIRAD. HIRAD was conceived in the early 2000s and involved several phases of design and development, culminating in its first test flights in 2010. Upcoming plans include HIRAD participating in hurricane field campaigns to collect science data. The document outlines HIRAD's design including its planar antenna array and correlating receiver architecture.

1. From a Real Pencil to a Synthetic Broom: The Past, Present and Future of HIRAD Chris Ruf Space Physics Research Laboratory AOSS Dept. University of Michigan and a large team of collaborators at NASA Marshall, the University of Central Florida, the University of Michigan, and the NOAA Hurricane Research Division IGARSS 2010 Honolulu, HI USA 26-30 July 2010 Univ. of Michigan Univ. of Alabama/Huntsville Univ. of Central Florida NASA NOAA

2. The Prehistoric Past The Stepped Frequency Microwave Radiometer (SFMR)

3. NOAA Hurricane Research Division Stepped Frequency Microwave Radiometer Horn Antenna SFMR electronics SFMR wing pod SFMR on NOAA WP3D Aircraft Wide band (4.6 - 7.2 GHz) receiver

4. Brightness Temperature Spectra for SFMR Hurricane Katrina Overpass

5. Retrieved Wind Speed & Rain Rate for SFMR Katrina Overpass Wind Speed Rain Rate

6. Jones et al ., Science, vol. 214, 1981.

7. Jones et al ., Science, vol. 214, 1981.

8. The Recent Past Birth of the HIRAD Project

12. Fourier Synthesis Synthetic Aperture Measurement Concept Interferometer as Spatial Frequency Filter

15. HIRAD Functional Block Diagram

16. The Present HIRAD System Integration and Test and First Engineering Test Flights

17. Interference Pattern Measurements to Derive Imaging Impulse Response

18. April 2010 Anechoic Chamber Results 5 GHz Element and Interference Patterns

19. 5 GHz Synthesized Antenna Patterns at -60 deg, nadir, +60 deg

20. Nadir Mainbeams of all 4 Synthesized Antenna Patterns nadir HPBW 4 GHz 3.2 deg 5 GHz 2.6 deg 6 GHz 2.4 deg 6.6 GHz 2.3 deg

21. HIRAD Integration on WB-57 March 2010

22. HIRAD WB-57 flights on 9 and 11 Mar 2010 11 Mar flight 9 Mar flight First look

23. 9 Mar 2010 HIRAD WB-57 flight TB @ 5 GHz during coastal crossing flight line

24. The Future HIRAD participation in Genesis and Rapid Intensification Process (GRIP) (Fall 2010) and Airborne Venture-class mission “Hurricane and Severe Storm Sentinel”, Scott Braun (PI) (2011-2016)