This manuscript presents the Microwave Temperature and Humidity Profiler (MTHP), a dual-band spectroradiometer designed for measuring multi-incidence angle temperature and humidity atmospheric ...profiles from an aircraft platform. The MTHP bands are at 60 GHz for measuring the oxygen complex lines, therefore at this band, MTHP has a hyperspectral radiometer able to provide 2048 channels over an 8 GHz bandwidth, and 183 GHz for measuring water vapor, which only uses four channels since this absorption band’s spectral richness is simpler. The MTHP builds upon the Microwave Temperature Profiler (MTP) with the inclusion of the hyperspectral radiometer. The instrument’s design, components, and calibration methods are discussed in detail, with a focus on the three-point calibration scheme involving internal calibration loads and static air temperature readings. Preliminary results from the Technological Innovation into Iodine and GV aircraft Environmental Research (TI3GER) campaign are presented, showcasing the instrument’s performance during flights across diverse geographical regions. The manuscript presents successful antenna temperature measurements at 60 GHz and 183 GHz. The hyperspectral measurements are compared with a simulated antenna temperature using the Atmospheric Radiative Transfer Simulator (ARTS) showing an agreement better than R2 > 0.88 for three of the flights analyzed. Additionally, the manuscript draws attention to potential Radio Frequency Interference (RFI) effects observed during a specific flight, underscoring the instrument’s sensitivity to external interference. This is the first-ever airborne demonstration of a broadband and hyperspectral multi-incidence angle 60 GHz measurement. Future work on the MTHP could result in an improved spatial resolution of the atmospheric temperature vertical profile and, hence, help in estimating the Planetary Boundary Layer (PBL) with better accuracy. The MTHP and its hyperspectral multi-incidence angle at 60 GHz have the potential to be a valuable tool for investigating the PBL’s role in atmospheric dynamics, offering insights into its impact on Earth’s energy, water, and carbon cycles.
The feasibility of using CMOS technology for RF amplification in atmospheric remote sensing receiver is studied. The design and measurement results of a 200-GHz low-noise amplifier which is ...fabricated using a 32-nm SOI CMOS technology are presented. The 8-stage amplifier in a common-source configuration achieves a 9-dB noise figure and 25-dB gain with a power consumption of 33 mW.
The design, error budget, and preliminary test results of a 50-56-GHz synthetic aperture radiometer demonstration system are presented. The instrument consists of a fixed 24-element array of ...correlation interferometers and is capable of producing calibrated images with 1deg spatial resolution within a 17deg wide field of view. This system has been built to demonstrate a performance and a design which can be scaled to a much larger geostationary Earth imager. As a baseline, such a system would consist of about 300 elements and would be capable of providing contiguous full hemispheric images of the Earth with 1 K of radiometric precision and 50-km spatial resolution. An error budget is developed around this goal and then tested with the demonstrator system. Errors are categorized as either scaling (i.e., complex gain) or additive (noise and bias) errors. Sensitivity to gain and/or phase error is generally proportional to the magnitude of the expected visibility, which is high only in the shortest baselines of the array, based on model simulations of the Earth as viewed from geostationary Earth orbit. Requirements range from approximately 0.5% and 0.3deg of amplitude and phase uncertainty, respectively, for the closest spacings at the center of the array, to about 4% and 2.5deg for the majority of the array. The latter requirements are demonstrated with our instrument using relatively simple references and antenna models, and by relying on the intrinsic stability and efficiency of the system. The 0.5% requirement (for the short baselines) is met by measuring the detailed spatial response (e.g., on the antenna range) and by using an internal noise diode reference to stabilize the response. This result suggests a hybrid image synthesis algorithm in which long baselines are processed by a fast Fourier transform and the short baselines are processed by a more precise (G-matrix) algorithm which can handle small anomalies among antenna and receiver responses. Visibility biases and other additive errors must be below about 1.5 mK on average, regardless of baseline. The bias requirement is largely met with a phase-shifting scheme applied to the local oscillator distribution of our demonstration system. Low mutual coupling among the horn antennas of our design is also critical to minimize the biases caused by crosstalk of receiver noise. Performance is validated by a three-way comparison between interference fringes measured on the antenna range, solar transit observations, and the system model.
We report W-band GaN MMIC's that produce 96% more power at a frequency of 88 GHz in continuous wave (CW) operation than the highest power reported in this frequency band for the best competing solid ...state technology, the InP HEMT. W-band power module containing a single three stage GaN MMIC chip with 600 μm wide output stage produced over 842 mW of output power in CW-mode, with associated PAE of 14.7% and associated power gain of 9.3 dB. This performance was measured at MMIC drain bias of 14 V.
We report two resistive mixers, i.e., a balanced and a balanced image-rejection (IR) mixer for the 60-GHz frequency range. A compact and wide-band method for the local-oscillator (LO) power division ...is presented. The 56-GHz LO signal, which propagates in a coplanar-waveguide mode, is divided in between the lines of two spiral baluns. Consequently, a smooth and compact transition from even-to-odd propagation mode and an in-phase power division for two singly balanced unit mixers is achieved. As a result, the developed IR mixer occupies only 1.41mm/sup 2/ of chip area. The balanced design achieved 11.5 dB of conversion loss from 57 to 67 GHz with a fixed IF of 5.3 GHz. The corresponding LO suppression was better than 34 dB with 8 dBm of LO power. The IR mixer achieved better than 19 dB of IR ratio and better than 36 dB of LO suppression for an RF frequency from 57 to 66 GHz. The corresponding conversion loss varies from 13 to 16 dB. The measured 1-dB compression point of the IR mixer was at a -13-dBm output power level and the third-order intercept point was at a 4-dBm level.
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
We present new results for a two-port vector network analyzer swept-frequency test set for the 325-508 GHz frequency band. The calibrated dynamic range performance in the full frequency band is ...discussed. Using a line-reflect-line calibration procedure, the dynamic ranges for return and insertion losses of better than 20 and 35 dB, respectively, are achieved. We examine the performance of the calibrated test set for the first time by measuring S-parameters of passive waveguide components and comparing data with electromagnetic simulations.
Millimeter-wave signals are typically generated by frequency multiplication in modern single-chip or multichip module (MCM) systems. Consequently, the multiplication efficiency, spurious rejection, ...and size of the frequency multiplier ultimately limit the integration level and cost of these systems. This paper points to the size reduction of millimeter-wave frequency doublers by evaluating artificial transmission lines (ATL's) as a means to minimize the size of the low-impedance shunt stubs. As a result, we developed a 40-GHz frequency doubler, which used only 0.6-mm/sup 2/ area on a monolithic microwave integrated circuit. Despite the area minimization, the doubler exhibited state-of-the-art conversion loss of 1 dB over 10% bandwidth and rejected the fundamental frequency signal by more than 20 dB over 25% bandwidth. Reported herein is the novel simulation of the frequency doubler with active harmonic loads. Included in this paper are theoretical evaluation and simulation of ATL's with models for lumped components and verification of the results by electromagnetic simulation. Due to the high efficiency, low area requirement, and over 20-dB rejection of the fundamental signal, this miniaturized ATL frequency doubler can be used as a building block in the generation of local-oscillator signals in single-chip and MCM millimeter-wave systems.
The Precipitation and All-weather Temperature and Humidity (PATH) mission is one of the NASA missions recommended by the NRC in its recent Earth Science "Decadal Survey." The focus of this mission is ...on the hydrologic cycle in the atmosphere, with applications from weather forecasting to climate research. PATH will deploy a microwave sounder, a passive radiometer that measures upwelling thermal radiation, in geostationary orbit and will for the first time provide a time-continuous view of atmospheric temperature and all three phases of water under nearly all weather conditions. This is possible because microwave radiation is sensitive to but also penetrates both clouds and precipitation, as has been demonstrated with similar sensors on low-earth-orbiting satellites. Data from those sensors, despite observing a particular location only twice a day, have had more impact on weather prediction accuracy than any other type of satellite sensor, and it is expected that PATH will have a similar impact with its ability to continuously observe the entire life cycle of storm systems. Such sensors have also played an important role in climate research and have been used to estimate long-term temperature trends in the atmosphere. An important application of PATH data will be to improve the representation of cloud formation, convection, and precipitation in weather and climate models, particularly the diurnal variation in those processes. In addition to measuring the three-dimensional distribution of temperature, water vapor, cloud liquid water, and ice, PATH also measures sea surface temperature under full cloud cover. Such observations make a number of important applications possible. Depending on the application focus and the geostationary orbit location, PATH can serve as anything from a hurricane and severe-storm observatory to an El Niño observatory. A geostationary orbit offers many advantages, as has been demonstrated with visible and infrared imagers and sounders deployed on weather satellites, but those sensors cannot penetrate clouds. It has not been possible until now to build a microwave radiometer with a large enough antenna aperture to attain a reasonable spatial resolution from a GEO orbit. A new approach, using aperture synthesis, has recently been developed by NASA at the Jet Propulsion Laboratory, and that is what makes PATH possible. Key technology enabling the large array of receivers in such a system has been developed, and a proof-of-concept demonstrator was completed in 2006. The state of the art in this area is now such that PATH mission development could start in 2010 and be ready for launch in 2015, but the actual schedule depends on the availability of funding. An option to fly PATH as a joint NASA-NOAA mission is being explored.
PDF
