30 GHz Printed Ridge Gap Components and Antennas for Imaging Systems

Working at millimeter waves (MMW) has gained massive attention for wireless communications and imaging systems. For imaging systems, MMW can be used for security to provide good resolution images and detect concealed weapons as it can penetrate common clothes and reflect from the human body and metal objects. Moreover, MMW is safe for human health, contrary to conventional X-ray imaging, which uses an ionized wave. Thus, it has a harmful effect on human health. This research is focusing on building an active wide-view angle millimeter-wave imaging system with a small area of mechanical movement to reduce the data collection time. The imaging system is composed of three main parts: 1) the millimeter-wave components and antennas, 2) the mechanical part for moving the antennas and performing the scan of the imaging area, and 3) the imaging reconstruction algorithm. In order to have an efficient imaging system, the printed ridge gap technology (PRGW) is used to build the imaging system components and antennas. High efficiency coaxial to PRGW transition with a fractional bandwidth of 59.22% at 32.25 GHz is designed to feed the system components. For the transmitting part of the imaging system, a moderate gain PRGW differential feeding planar aperture antenna and a wideband rat-race coupler are designed. The antenna, the rat-race, and the coaxial transition are combined to form the transmitting part, then fabricated and measured. The resulted bandwidth is from 25.62 to 34.34 GHz with a return loss better than 10 dB, a maximum gain of 12.28 dBi, and 3-dB gain bandwidth from 25.62 to 33.77 GHz. For the receiving antenna, a PRGW Butler matrix and its components (directional couplers, 45◦ phase shifters, and crossovers) are designed. A semi-log periodic antenna fed by the PRGW is designed as the radiating element. The PRGW components, the coaxial transition, and the antennas are combined to form the receiving part of the imaging system, which is fabricated and measured. The resulting beam directions are at ±13◦ and ±36◦, at the center frequency (30 GHz). The return loss and the isolations are better than 10 dB over the frequency range from 26.1 to 33.5 GHz. For the imaging reconstruction algorithm, a synthetic aperture radar algorithm is used. Two tests are carried out, one uses CST simulation results, and the other uses measured data from the Concordia antenna chamber lab. The results show an output resolution of 0.6 λ. Finally, the whole imaging system is built with the designed differential feeding antenna as the transmitter, the designed Butler matrix as the receiver, and the synthetic aperture algorithm as the image reconstruction algorithm. The performance network analyzer (PNA) is used to collect the data (s-parameters) required to reconstruct the image, and the antenna range controller system (NSI 5913) is used to mechanically scan the imaging area. The imaging system is used to scan a mannequin carrying an object shaped like a pistol and a knife. The results show that the two objects are detected

WSR: A WiFi Sensor for Collaborative Robotics

In this paper we derive a new capability for robots to measure relative direction, or Angle-of-Arrival (AOA), to other robots operating in non-line-of-sight and unmapped environments with occlusions, without requiring external infrastructure. We do so by capturing all of the paths that a WiFi signal traverses as it travels from a transmitting to a receiving robot, which we term an AOA profile. The key intuition is to "emulate antenna arrays in the air" as the robots move in 3D space, a method akin to Synthetic Aperture Radar (SAR). The main contributions include development of i) a framework to accommodate arbitrary 3D trajectories, as well as continuous mobility all robots, while computing AOA profiles and ii) an accompanying analysis that provides a lower bound on variance of AOA estimation as a function of robot trajectory geometry based on the Cramer Rao Bound. This is a critical distinction with previous work on SAR that restricts robot mobility to prescribed motion patterns, does not generalize to 3D space, and/or requires transmitting robots to be static during data acquisition periods. Our method results in more accurate AOA profiles and thus better AOA estimation, and formally characterizes this observation as the informativeness of the trajectory; a computable quantity for which we derive a closed form. All theoretical developments are substantiated by extensive simulation and hardware experiments. We also show that our formulation can be used with an off-the-shelf trajectory estimation sensor. Finally, we demonstrate the performance of our system on a multi-robot dynamic rendezvous task.Comment: 28 pages, 25 figures, *co-primary author

NASA Tech Briefs, June 1992

Topics covered include: New Product Ideas; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences; Life Sciences

SPICA:revealing the hearts of galaxies and forming planetary systems : approach and US contributions

How did the diversity of galaxies we see in the modern Universe come to be? When and where did stars within them forge the heavy elements that give rise to the complex chemistry of life? How do planetary systems, the Universe's home for life, emerge from interstellar material? Answering these questions requires techniques that penetrate dust to reveal the detailed contents and processes in obscured regions. The ESA-JAXA Space Infrared Telescope for Cosmology and Astrophysics (SPICA) mission is designed for this, with a focus on sensitive spectroscopy in the 12 to 230 micron range. SPICA offers massive sensitivity improvements with its 2.5-meter primary mirror actively cooled to below 8 K. SPICA one of 3 candidates for the ESA's Cosmic Visions M5 mission, and JAXA has is committed to their portion of the collaboration. ESA will provide the silicon-carbide telescope, science instrument assembly, satellite integration and testing, and the spacecraft bus. JAXA will provide the passive and active cooling system (supporting the

The Apertif Surveys:The First Six Months

Apertif is a new phased-array feed for the Westerbork Synthesis Radio Telescope (WSRT), greatly increasing its field of view and turning it into a natural survey instrument. In July 2019, the Apertif legacy surveys commenced; these are a time-domain survey and a two-tiered imaging survey, with a shallow and medium-deep component. The time-domain survey searches for new (millisecond) pulsars and fast radio bursts (FRBs). The imaging surveys provide neutral hydrogen (HI), radio continuum and polarization data products. With a bandwidth of 300 MHz, Apertif can detect HI out to a redshift of 0.26. The key science goals to be accomplished by Apertif include localization of FRBs (including real-time public alerts), the role of environment and interaction on galaxy properties and gas removal, finding the smallest galaxies, connecting cold gas to AGN, understanding the faint radio population, and studying magnetic fields in galaxies. After a proprietary period, survey data products will be publicly available through the Apertif Long Term Archive (ALTA, https://alta.astron.nl). I will review the progress of the surveys and present the first results from the Apertif surveys, including highlighting the currently available public data

An Assessment of Indoor Geolocation Systems

Currently there is a need to design, develop, and deploy autonomous and portable indoor geolocation systems to fulfil the needs of military, civilian, governmental and commercial customers where GPS and GLONASS signals are not available due to the limitations of both GPS and GLONASS signal structure designs. The goal of this dissertation is (1) to introduce geolocation systems; (2) to classify the state of the art geolocation systems; (3) to identify the issues with the state of the art indoor geolocation systems; and (4) to propose and assess four WPI indoor geolocation systems. It is assessed that the current GPS and GLONASS signal structures are inadequate to overcome two main design concerns; namely, (1) the near-far effect and (2) the multipath effect. We propose four WPI indoor geolocation systems as an alternative solution to near-far and multipath effects. The WPI indoor geolocation systems are (1) a DSSS/CDMA indoor geolocation system, (2) a DSSS/CDMA/FDMA indoor geolocation system, (3) a DSSS/OFDM/CDMA/FDMA indoor geolocation system, and (4) an OFDM/FDMA indoor geolocation system. Each system is researched, discussed, and analyzed based on its principle of operation, its transmitter, the indoor channel, and its receiver design and issues associated with obtaining an observable to achieve indoor navigation. Our assessment of these systems concludes the following. First, a DSSS/CDMA indoor geolocation system is inadequate to neither overcome the near-far effect not mitigate cross-channel interference due to the multipath. Second, a DSSS/CDMA/FDMA indoor geolocation system is a potential candidate for indoor positioning, with data rate up to 3.2 KBPS, pseudorange error, less than to 2 m and phase error less than 5 mm. Third, a DSSS/OFDM/CDMA/FDMA indoor geolocation system is a potential candidate to achieve similar or better navigation accuracy than a DSSS/CDMA indoor geolocation system and data rate up to 5 MBPS. Fourth, an OFDM/FDMA indoor geolocation system is another potential candidate with a totally different signal structure than the pervious three WPI indoor geolocation systems, but with similar pseudorange error performance