This document discusses the development of millimeter-wave radiometers operating at 130 and 166 GHz to support the Surface Water and Ocean Topography (SWOT) mission. Key components developed include monolithic microwave integrated circuit (MMIC)-based pin diode switches covering 80-190 GHz and prototype radiometers at 130 and 166 GHz. The high frequency radiometers aim to enable wet path delay measurements closer to coastlines and over land to support the SWOT mission objectives.

1. DEVELOPMENT OF INTERNALLY-CALIBRATED, MMIC-BASED MILLIMETER-WAVE RADIOMETERS OPERATING AT 130 AND 166 GHZ IN SUPPORT OF THE SWOT MISSION Alexander Lee, Darrin Albers, and Steven C. Reising Microwave Systems Laboratory, Colorado State University, Fort Collins, CO PekkaKangaslahti, Shannon T. Brown, Douglas E. Dawson, Oliver Montes, Todd C. Gaier, Daniel J. Hoppe, and BehrouzKhayatian Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA

2. Surface Water and Ocean Topography (SWOT) Mission Accelerated Tier-2 U.S. National Research Council Earth Science Decadal Survey Mission planned for launch in 2020 (NASA/CNES partnership) Oceanography Objectives: Characterize ocean mesoscale and sub-mesoscale circulation at spatial resolutions of 10 km and larger (1-cm ht. precision required) Kinetic energy / Heat and carbon air-sea fluxes Climate change and ocean circulation Coastal and internal tides Hydrology Objectives: To provide global height measurements of inland surface water bodies with area greater than 250 m2 and rivers with width greater than 100 m To measure change in global water storage in these inland water bodies and river discharge on sub-monthly to annual time scales Lee et al., FR3.T03 July 29, 2011 2 IGARSS 2011 Vancouver, B.C. Canada

4. SWOT Mission Concept Study Low frequency-only algorithm Low frequency-only algorithm Low and High frequency algorithm Low and High frequency algorithm High-resolution Weather Research and Forecasting (WRF) model results show reduced wet path-delay error using both low-frequency (18-37 GHz) and high-frequency (90-170 GHz) radiometer channels. Lee et al., FR3.T03 July 29, 2011 4 IGARSS 2011 Vancouver, B.C. Canada

6. Design and fabricate a tri-frequency feed horn with integrated triplexer covering 90 to 170 GHz

7. Design and fabricate PIN-diode switches and noise diodes for internal calibration from 90 to 170 GHz that can be integrated into the receiver front end

8. Integrate and test components in MMIC-based low-mass, low-power, small-volume radiometer at 92, 130 and 166 GHz with the tri-frequency feed hornLee et al., FR3.T03 July 29, 2011 5 IGARSS 2011 Vancouver, B.C. Canada

10. Monolithic microwave integrated circuits (MMIC) wererealized in microstrip and coplanar waveguide technology

11. Fabricated using Northrop Grumman’s 75-μm thick InP MMIC PIN diodeprocess

12. PIN diodes used because of low insertionloss and fast switching speeds

13. Variations of each SPDT design with PIN diode sizes ranging from 3 to 8 μm were fabricated

14. To date, 80-105 GHz and 90-135 GHz switches have been tested; 160-190 switches have not yet been tested Lee et al., FR3.T03 July 29, 2011 6 IGARSS 2011 Vancouver, B.C. Canada

16. SiN 2-layer MIM capacitors for bypass and DC blocking capacitors

17. NiCr thin-film process for resistors

18. Radial stubs used to provide well-defined virtual RF shorts

19. Antenna and Common legs aligned and Reference leg at a 90°angle Asymmetric Design 1.52 mm Antenna Leg Common Leg 1.37 mm Measured Performance Insertion Loss Common Leg RL (Integrated Ref. Load Version) Isolation Reference Leg Common Leg RL Antenna Leg RL Asymmetric design variation with integrated 50-Ω reference termination Lee et al., FR3.T03 July 29, 2011 7 IGARSS 2011 Vancouver, B.C. Canada

21. By increasing effective electrical length of shunt diode radial stubs, optimal isolation was lowered to frequency range of interest Measured Performance Isolation (Un-tuned) Tuning ribbon added to shunt diode radial stub Isolation (Tuned) Lee et al., FR3.T03 July 29, 2011 8 IGARSS 2011 Vancouver, B.C. Canada

22. 90-135 GHz MMIC Switch Symmetric Design Measured Performance Same technology as 80-105 GHz design (microstrip, SiN 2-layer MIM capacitors, etc.) Insertion Loss 1.52 mm Isolation Antenna Leg RL Antenna Leg Reference Leg 1.37 mm Common Leg RL Common Leg Preliminary tuning of shunt diode radial stub demonstrates decrease in isolation optimal frequency Lee et al., FR3.T03 July 29, 2011 9 IGARSS 2011 Vancouver, B.C. Canada

24. SiN 2-layer MIM capacitors for bypass and DC blocking capacitors

25. NiCr thin-film process for resistors1.10 mm 0.97 mm Reference Leg Antenna Leg Simulated Performance Insertion Loss Common Leg RL Common Leg Isolation Antenna Leg RL Lee et al., FR3.T03 July 29, 2011 10 IGARSS 2011 Vancouver, B.C. Canada

26. PIN Diode Switch Results Lee et al., FR3.T03 July 29, 2011 11 IGARSS 2011 Vancouver, B.C. Canada

27. System Block Diagram 92-GHz multi-chip module Waveguide Components MMIC Components Coupler Tri-Frequency Feed Horn Noise Diode Common radiometer back end, thermal control and data subsystem 130-GHz multi-chip module Coupler Noise Diode Coupler 166-GHz multi-chip module Noise Diode Lee et al., FR3.T03 July 29, 2011 12 IGARSS 2011 Vancouver, B.C. Canada

30. 130-GHz Predicted Performance Lee et al., FR3.T03 July 29, 2011 15 IGARSS 2011 Vancouver, B.C. Canada

31. 166-GHz Predicted Performance Lee et al., FR3.T03 July 29, 2011 16 IGARSS 2011 Vancouver, B.C. Canada

32. 166-GHz Predicted Performance Lee et al., FR3.T03 July 29, 2011 17 IGARSS 2011 Vancouver, B.C. Canada

33. 166-GHz Band Pass Filter:Return Loss 0.94” (2.4 mm) Lee et al., FR3.T03 July 29, 2011 18 The passive high-frequency microwave components were designed and fabricated in microstrip technology on 3-mil (75 μm) thick alumina substrates. IGARSS 2011 Vancouver, B.C. Canada

34. 166-GHz Band Pass Filter:Insertion Loss Lee et al., FR3.T03 July 29, 2011 19 IGARSS 2011 Vancouver, B.C. Canada

35. 166-GHz Matched Load The passive high-frequency microwave components were designed and fabricated in microstrip technology on 3-mil (75 μm) thick alumina substrates. Lee et al., FR3.T03 July 29, 2011 20 IGARSS 2011 Vancouver, B.C. Canada 0.029” (.74 mm)

36. 130-GHz Multi-Chip Module 50Ω ATN SW BPF-2 LNA LNA BPF-1 LNA LNA WTM 0.094” (2.39 mm) 0.077” (1.96 mm) WTM 0.8” (20.3 mm) 1.45” (36.8 mm) 1.75” (44.5 mm) Lee et al., FR3.T03 July 29, 2011 21 IGARSS 2011 Vancouver, B.C. Canada

37. 130-GHz Multi-Chip Module Lee et al., FR3.T03 July 29, 2011 22 IGARSS 2011 Vancouver, B.C. Canada

38. 166-GHz Multi-Chip Module 0.093” (2.4 mm) Lee et al., FR3.T03 July 29, 2011 23 IGARSS 2011 Vancouver, B.C. Canada

39. Multi-Chip Module Assembly Lee et al., FR3.T03 July 29, 2011 24 IGARSS 2011 Vancouver, B.C. Canada

41. Key radiometer component technologies are under development to enable additional high frequency radiometers operating at 92 GHz, 130 GHz, and 166 GHz for the upcoming SWOT mission.

42. High frequency switches have been designed and fabricated for all three high frequency radiometers.

43. Switch testing has been completed on the 92 GHz and 130 GHz switches. The test results show less than 2 dB insertion loss and greater than 15 dB return loss. Additional tuning is required to optimize the isolation.

44. Prototype radiometers at 130 GHz and 166 GHz have been designed and are in the process of being fabricated.IGARSS 2011 Vancouver, B.C. Canada

45. Backup Slides Lee et al., FR3.T03 July 29, 2011 26 IGARSS 2011 Vancouver, B.C. Canada

46. Move to Higher Frequency 22.235 GHz (H2O) 118 GHz (O2) 55-60 GHz (O2) 183.31 GHz (H2O) Supplement low-frequency, low-spatial resolution channels with high-frequency, high-spatial resolution channels to retrieve PD near coast High-frequency window channels sensitive to water vapor continuum 183 GHz channels sensitive to water vapor at different layers in atmosphere Lee et al., FR3.T03 July 29, 2011 27 IGARSS 2011 Vancouver, B.C. Canada

48. Eliminates the need for quarter-wave transformer (reduces size)

49. This configuration was used for SPDT switch designs being presentedRF OUTPUT RF OUTPUT RF INPUT Lee et al., FR3.T03 July 29, 2011 28 IGARSS 2011 Vancouver, B.C. Canada

50. Design Topology SPDT Switch Circuit Schematic Lee et al., FR3.T03 July 29, 2011 29 IGARSS 2011 Vancouver, B.C. Canada

52. SiN 2-layer MIM capacitors for bypass and DC blocking capacitors

53. NiCr thin-film process for resistors

54. Radial stubs used to provide well-defined virtual RF shortsSymmetric Design 1.52 mm Antenna Leg Reference Leg 1.37 mm Measured Performance Insertion Loss Common Leg Isolation Common Leg RL Antenna Leg RL Lee et al., FR3.T03 July 29, 2011 30 IGARSS 2011 Vancouver, B.C. Canada

55. 80-105 GHz MMIC Switch Measured Results vs. Simulated Results Lee et al., FR3.T03 July 29, 2011 31 IGARSS 2011 Vancouver, B.C. Canada

58. Three-stage design with separate gate bias for the first stage to optimize low-noise performance

59. Record low noise temperature of 300 K from 150 - 160 GHz

60. Chip area of 900 x 560 (μm)2

61. The LNA was mounted in optimized WR-08 and WR-05 waveguide housings to test over a broad bandwidth.Lee et al., FR3.T03 July 29, 2011 33 IGARSS 2011 Vancouver, B.C. Canada

62. 130-GHz Band Pass Filter:Return Loss The passive high-frequency microwave components were designed and fabricated in microstrip technology on 3-mil (75 μm) thick alumina substrates. 0.94” (2.4 mm) Lee et al., FR3.T03 July 29, 2011 34 IGARSS 2011 Vancouver, B.C. Canada

63. 130-GHz Band Pass Filter:Insertion Loss Note: Correction for CPW losses included Lee et al., FR3.T03 July 29, 2011 35 IGARSS 2011 Vancouver, B.C. Canada