Douglas Dawson

Beyond G-band: a 235 GHz InP MMIC amplifier

We present results on an InP monolithic millimeter-wave integrated circuit (MMIC) amplifier having 10-dB gain at 235GHz. We designed this circuit and fabricated the chip in Northrop Grumman Space Technologys (NGST) 0.07-/spl mu/m InP high electron mobility transistor (HEMT) process. Using a WR3 (220-325GHz) waveguide vector network analyzer system interfaced to waveguide wafer probes, we measured this chip on-wafer for S-parameters. To our knowledge, this is the first time a WR3 waveguide on-wafer measurement system has been used to measure gain in a MMIC amplifier above 230GHz.

On-Wafer Vector Network Analyzer Measurements in the 220-325 GHz Frequency Band

We report on a full two-port on-wafer vector network analyzer test set for the 220-325 GHz (WR3) frequency band. The test set utilizes Oleson Microwave Labs frequency extenders with the Agilent 8510C network analyzer. Two port on-wafer measurements are made with GGB Industries coplanar waveguide (CPW) probes. With this test set we have measured the WR3 band S-parameters of amplifiers on-wafer, and the characteristics of the CPW wafer probes. Results for a three stage InP HEMT amplifier show 10 dB gain at 235 GHz as presented in D. Dawson et al. (2005), and that of a single stage amplifier, 2.9 dB gain at 231 GHz. The approximate upper limit of loss per CPW probe range from 3.0 to 4.8 dB across the WR3 frequency band

Two-Port Vector Network Analyzer Measurements in the 218–344- and 356–500-GHz Frequency Bands

We discuss methods for full two-port vector network analyzer measurements in the 218-344- (using WR3) and 356-500-GHz (using WR2.2) frequency bands. Waveguide test sets (WR3 and WR2.2) utilize Oleson Microwave Laboratories Inc. frequency extenders with the Agilent 8510C network analyzer. On-wafer measurements in the 220-325-GHz band are demonstrated with GGB Industries Inc. coplanar-waveguide probes. This paper primarily reviews the performance capabilities of the WR3 test set and introduces initial calibration results of the WR2.2 test set. For WR3, calibration methods are compared, and dynamic range and frequency extender output power data are presented

SMAP L-Band Microwave Radiometer: Instrument Design and First Year on Orbit

The Soil Moisture Active–Passive (SMAP) L-band microwave radiometer is a conical scanning instrument designed to measure soil moisture with 4% volumetric accuracy at 40-km spatial resolution. SMAP is NASA’s first Earth Systematic Mission developed in response to its first Earth science decadal survey. Here, the design is reviewed and the results of its first year on orbit are presented. Unique features of the radiometer include a large 6-m rotating reflector, fully polarimetric radiometer receiver with internal calibration, and radio-frequency interference detection and filtering hardware. The radiometer electronics are thermally controlled to achieve good radiometric stability. Analyses of on-orbit results indicate that the electrical and thermal characteristics of the electronics and internal calibration sources are very stable and promote excellent gain stability. Radiometer NEDT < 1 K for 17-ms samples. The gain spectrum exhibits low noise at frequencies >1 MHz and 1/f noise rising at longer time scales fully captured by the internal calibration scheme. Results from sky observations and global swath imagery of all four Stokes antenna temperatures indicate that the instrument is operating as expected.

Low noise amplifier receivers for millimeter wave atmospheric remote sensing

We currently achieve 3.4 dB noise figure at 183GHz and 2.1 dB noise figure at 90 GHz with our MMIC low noise amplifiers (LNAs) in room temperature. These amplifiers and the receivers we have built using them made it possible to conduct highly accurate airborne measurement campaigns from the Global Hawk unmanned aerial vehicle, develop millimeter wave internally calibrated radiometers for altimeter radar path delay correction, and build prototypes of large arrays of millimeter receivers for a geostationary interferometric sounder. We use the developed millimeter wave receivers to measure temperature and humidity profiles in the atmosphere and in hurricanes as well as to characterize the path delay error in ocean topography altimetry.

On-Wafer S-Parameter Measurements in the 325–508 GHz Band

We report on two-port on-wafer vector network analyzer measurements in the 325-508 GHz frequency band. Measurements are made with prototype GGB Industries Inc. WR2.2 (325-500 GHz) coplanar waveguide probes and OML Inc. WR2.2 frequency extenders. New probe performance data and characteristics of probe tip calibration using a Thru-Reflect-Line procedure are discussed. Probe S-parameter measurements indicate insertion loss per probe of 5.0 to 9.1 dB in the WR2.2 band. Calibrated dynamic range of about 30 dB or better for insertion and return loss measurement across the band is achieved. These new results for the prototype WR2.2 probes, the calibration procedure, observed errors, and results of on-wafer amplifier measurements are presented.

InP HEMT low-noise amplifier-based millimeter-wave radiometers from 90 to 180 GHz with internal calibration for remote sensing of atmospheric wet-path delay

The recent introduction of 35-nm gate length InP MMIC low-noise amplifiers has enabled significant advances in Earth remote sensing. These low-noise amplifiers achieve 2-dB and 3-dB noise figure at 180 GHz and 90 GHz, respectively, at room temperature. For Earth remote sensing using ocean surface altimeters, the design of new millimeter-wave radiometers is motivated by the fact that these missions include nadir-viewing, co-located 18–37 GHz microwave radiometers to measure wet-tropospheric path delay. However, due to the substantial area of the surface instantaneous fields of view (IFOV) at these frequencies, the accuracy of wet path retrievals begins to degrade at approximately 50 km from the coasts. In addition, conventional microwave radiometers do not provide wet-path delay over land. For a maximum antenna aperture size on Earth observation satellites, the addition of higher-frequency millimeter-wave (90–170 GHz) radiometers to current Jason-class radiometers is expected to improve retrievals of wet-tropospheric delay in coastal areas and to increase the potential for over-land retrievals.

Development of the Radiometer Atmospheric CubeSat Experiment payload

The Jet Propulsion Laboratory (JPL) is developing the Radiometer Atmospheric CubeSat Experiment (RACE), which consists of a water vapor radiometer integrated on a 3 U CubeSat platform. RACE will measure 2 channels off the 183 GHz water vapor line, and will be used to validate new low noise amplifier technology and internal calibration methodology. RACE will advance the technology readiness level (TRL) of the 183 GHz receiver subsystem from TRL 4 to TRL 6 and a CubeSat 183 GHz radiometer system from TRL 4 to TRL 7.

SMAP RFI mitigation algorithm performance characterization using airborne high-rate direct-sampled SMAPVEX 2012 data

The SMAP RFI detecting digital backend performance is characterized using real-environment L-band RFI data from the SMAPVEX 2012 campaign. Various types of RFI signals are extracted from the airborne campaign dataset and fed to the SMAP radiometer using an Arbitrary Waveform Generator (AWG). The backend detection performance is tested, and missed-detections are further investigated. Initial results indicate RFI detection performance for the SMAP digital backend is acceptable.

Cryogenic measurements of 183 GHz MMIC low noise amplifiers

We report the packaging and first measurement of Indium Phosphide (InP) monolithic microwave integrated circuit (MMIC) low noise amplifiers (LNAs) operating at cryogenic temperatures above 140 GHz. The amplifiers were measured from 160 to 188 GHz at 20 K and tested for noise temperature and gain, with noise temperatures of 160 K. The packaging method and test setup are described, as well as detailed results at room and cryogenic temperatures.