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An overview of measurement techniques for millimeter wave substrate mounted antennas is presented. Scattering and pickup of the millimeter wave radiation on the low frequency leads is a significant problem in these measurements. Methods to reduce these effects are discussed, and preliminary work on dipole antennas at 230 GHz is presented.
An overview of measurement techniques for millimeter wave substrate mounted antennas is presented. Scattering and pickup of the millimeter wave radiation on the low frequency leads is a significant problem in these measurements. Methods to reduce these effects are discussed, and preliminary work on dipole antennas at 230 GHz is presented.
Images from an airborne, scanning radiometer operating at a frequency of 98 GHz have been analyzed. The millimeter-wave images were obtained in 1985-1986 using the JPL millimeter-wave imaging sensor. The goal of this study was to enhance the information content of these images and make their interpretation easier. A visual-interpretative approach was used for information extraction from the images. This included application of nonlinear transform techniques for noise reduction and for color, contrast, and edge enhancement. Results of using the techniques on selected millimeter-wave images are discussed.
The ATS-6 millimeter wave experiment, provided the first direct measurements of 20 and 30 GHz earth-space links from an orbiting satellite. Studies at eleven locations in the continental United States were directed at an evaluation of rain attenuation effects, scintillations, depolarization, site diversity, coherence bandwidth, and analog and digital communications techniques. In addition to direct measurements on the 20 and 30 GHz links, methods of attenuation prediction with radars, rain gages, and radiometers were developed and compared with the directly measured attenuation. Initial data results of the ATS-6 millimeter wave experiment from the major participating organizations are presented.
Including a one year No-Cost Extension, The University of California, Davis has been funded since 2020 to advance innovative millimeter-wave diagnostics for fusion plasma research. This work includes: (1) Developing and applying cutting-edge System-on-Chip millimeter wave Integrated Circuit (IC) technology for Electron Cyclotron Emission Imaging (ECEI) and Microwave Imaging Reflectometry (MIR) on the DIII-D tokamak and the NSTX-U spherical tokamak. (2) Development of radiation-hardened millimeter-wave chip for diagnostics in harsh environments, utilizing wide bandgap Gallium Nitride (GaN) semiconductors. (3) Integrating forward-modeling synthetic diagnostics to enable advanced, real-time plasma prediction and feedback control. Originally planned as a three-year program (2020–2023), the project was granted a one-year no-cost extension, extending its duration through the end of 2024.
The utility of microwave and millimeter wave nondestructive testing and evaluation (NDT&E) methods, for testing the Space Shuttle's external he1 tank spray on foam insulation (SOFI) and the acreage heat tiles has been investigated during the past two years. Millimeter wave NDE techniques are capable of producing internal images of SOFI. This paper presents the results of testing several diverse panels with embedded voids and debonds at millimeter wave frequencies. Additionally, the results of testing a set of heat tiles are also presented. Finally, the attributes of these methods as well as the advantageous features associated with these systems are also provided.
Next generation 5G mobile architectures will take advantage of the millimeter-wave spectrum to deliver unprecedented bandwidth. Concurrently, there is a need to consolidate numerous disparate allocations into a single, multi-functional array. Existing arrays are either narrow-band, prohibitively expensive or cannot be scaled to these frequencies. In this paper, we present the first ultra-wideband millimeter-wave array to operate across the six 5G and ISM bands spanning 24-71 GHz. Critically, the array is realized using low-cost PCB. The design concept and optimized layout are presented, and fabrication and measurement considerations are discussed.
In this paper the development and application of MODTool (Millimeter-wave Optics Design), a design tool that efficiently integrates existing millimeter-wave optics design software with a solid body modeler and thermal/structural analysis packages, will be discussed.
Microwave and millimeter wave nondestructive testing and evaluation (NDT&E) methods have shown great potential for determining material composition in composite structures, determining material thickness or debond thickness between two layers, and determining the location and size of flaws, defects, and anomalies. The same testing methods have also shown great potential to produce relatively high-resolution images of voids inside Spray On Foam Insulation (SOFI) test panels using real focused methods employing lens antennas. An alternative to real focusing methods are synthetic focusing methods. The essence of synthetic focusing is to match the phase of the scattered signal to measured points spaced regularly on a plane. Many variations of synthetic focusing methods have already been developed for radars, ultrasonic testing applications, and microwave concealed weapon detection. Two synthetic focusing methods were investigated; namely, a) frequency-domain synthetic aperture focusing technique (FDSAFT), and b) wide-band microwave holography. These methods were applied towards materials whose defects were of low dielectric contrast like air void in SOFI. It is important to note that this investigation used relatively low frequencies from 8.2 GHz to 26.5 GHz that are not conducive for direct imaging of the SOFI. The ultimate goal of this work has been to demonstrate the capability of these methods before they are applied to much higher frequencies such as the millimeter wave frequency spectrum (e.g., 30-300 GHz).
Tunnel diode fabrication techniques and circuits for millimeter wave receivers
Atmospheric effects on millimeter wave earth-space communication channels
Rectangular fence guides for millimeter wave transmission
In March 1979, millimeter-wave observations of the ozone emission line at 101737 MHz were made to measure the diurnal variations in mesospheric ozone. Changes in mesospheric ozone were measured diurnally for a 10-day period. The ozone column above approximately 76 km rapidly decreased after sunrise to half value within 1 hour and was then followed by a slower (approximately 8 hours) decrease to an absolute minimum at 1600 hours. At sunset, the ozone column above approximately 76 km increased rapidly to its maximum value within 2 hours. In the 48-68 km altitude range, the ozone changes were gradual with a minimum near local noon (1200 hours).
Sensitive millimeter-wave C-12O line observations and near-infrared hydrogen recombination line observations of AFGL 961 are reported and analyzed. The observations show that the high-velocity flow has a maximum extent of at least six arcmin or 1.9 pc at the distance of AFGL 961. The flow is anisotropic and the emission profiles are asymmetric in velocity. The mass of the gas involved in the flow is determined to be approximately 19 solar masses, and the kinetic energy of this gas is estimated to be about 8 x 10 to the 46th ergs. These observations are interpreted as evidence that an energetic bipolar outflow of molecular gas is occurring near AFGL 961. Comparison of infrared recombination line data, radio continuum, and CO observations shows that a strong, ionized, stellar wind would not be a sufficient force to drive the outflow. The effects of the outflow on the surrounding molecular cloud was also investigated.
High power millimeter wave sources for fusion program; ECH source development program strategy; and 1 MW, 140 GHz gyrotron experiment design philosophy are briefly outlined. This presentation is represented by viewgraphs only.
The Millimeter-Wave Thermal Launch System (MTLS) is a beamed-energy propulsion concept being designed at NASA Ames Research Center. This effort is in response to the NASA Office of the Chief Technologist s announcement of the Ride the Light program. Our objective is to produce a design that goes beyond the feasibility analysis level of previous studies and provides a solid foundation for low cost access to space. The MTLS is designed to place a 500 lb payload into Low Earth Orbit (LEO) two times a day. This frequent launch, small payload niche is well suited for the particular advantages and constraints of beamed-energy propulsion, and has the potential to drastically increase access to space by reducing the cost per kilogram of placing payloads into LEO. This paper summarizes the findings of the MTLS study. The chemical rocket engine is in principle a simple device. It acts by releasing the chemical energy stored in propellants such as hydrogen and oxygen through combustion, then converting that thermal energy into kinetic energy by expansion through a nozzle. As such, it is fundamentally limited by the energy released in combustion reactions and the molecular weight of the products of those reactions. The highest performing conventional propellant combination, liquid oxygen and liquid hydrogen, can produce vacuum specific impulses of around 450 seconds. The design space of current launch vehicles (which tend to be large, multi-stage, and expendable) are defined by these limitations. An entirely new approach may be necessary in order to enable future launch vehicles of radically improved capabilities. Beamed-energy propulsion (BEP) is an alternative approach that bypasses the energy limitations of chemical propulsion. Instead of relying on a chemical reaction as the energy source, it is supplied externally via a beam of electromagnetic energy produced on the ground. In the concept examined in the MTLS, this energy is absorbed by a heat exchanger which then transfers the energy to the propellant. This decouples the energy source from the working fluid, vastly expanding the design space. For example, a launch vehicle could use only water as propellant, making it very safe and easy to handle. However, the most commonly proposed way to take advantage of this decoupling is to use pure hydrogen as the working fluid, which enables specific impulses of around 800 seconds1 if the heat exchanger material can operate at 2200 K. With such a significantly increased Isp, it may be possible to build single-stage to orbit vehicles, with enough mass margins left over to permit lower cost fabrication techniques.
The development and construction of an ultralow noise heterodyne receiver for millimeter wave astronomy is described along with its use for 115.3 GHz Co line observations. The receiver uses a Superconductor-Insulator-Superconductor (SIS) quasiparticle tunnel junction mixer to convert the millimeter wave signal to a microwave intermediate frequency. Experiments aimed at quantitative verification of J. R. Tucker's quantum mixer theory are studied, to see whether it could be used as the basis for the design of a practical receiver. The experimental results were in excellent agreement with the theory, assuming the three frequency approximation. Infinite available gain and negative output resistance were observed for the first time, nonclassical effects which are not seen in conventional diode mixers. Using Tucker's theory, an SIS receiver was then designed and constructed. At 115 GHz, the single sideband receiver noise temperature is 83K, the lowest ever reported in this frequency range. A CO survey toward Cygnus-X region, using this SIS receiver on the Columbia-GISS 4 ft. telescope, is also described.
An active 3D microwave / millimeter-wave shoe scanner was previously developed at the Pacific Northwest National Laboratory (PNNL) using two linear arrays scanned over a rectilinear aperture. The radar system chirps a frequency sweep from 10-40 GHz. These frequencies allow imaging through optically opaque material such as leather, rubber, plastics, and other dielectrics. The system was designed to detect concealed items in the soles of shoes while allowing people to leave their shoes on through a security checkpoint. To shrink the footprint of the system, a new iteration of the design has been developed that scans the two linear arrays over a circular aperture. This new footprint opens the possibility of it being installed in the floor of a cylindrical millimeter-wave body scanner. The backprojection-based multilayer dielectric image reconstruction developed at PNNL can easily handle arbitrary spatial sampling, accommodating the new rotational shoe scanner design. Commonly, the fast Fourier transform (FFT) is used to efficiently compute the range response from the data collected by the system as a preprocessing step to the backprojection algorithm. It was found that converting to range using the discrete Fourier transform (DFT) directly has some advantages over the FFT. For example, nonlinear and non-uniform frequency sweeps can easily be compensated for during the computation of the DFT and only the range bins of interest need to be computed and their spacing can be chosen arbitrarily. Because the range conversion step of the image reconstruction is the fastest part of the process there is very little speed penalty for using the DFT over the FFT and it can even increase the speed of image reconstruction when the ranges of interest are fewer than the total span that is calculated in the FFT.