The research will create a technological first – a small, lightweight, low-cost phased-array radar that uses silicon-germanium (SiGe) chips in tandem with radio-frequency micro-electromechanical systems (RF MEMS). The system being developed could be mounted on aircraft or satellites to enable high-quality mapping of ice and snow formations.
Traditionally, research on frozen areas has required bulky radar equipment that must be operated on the surface, said John Papapolymerou, a professor in Georgia Tech's School of Electrical and Computer Engineering who is principal investigator on the project. The lightweight radar approach could allow unmanned aerial vehicles (UAVs) to gather information by flying over a large area such as Greenland, using the radar system to map ice sheets in three dimensions.
"This aerial approach would greatly facilitate environmental remote sensing of ice, allowing us to map larger areas of interest to better understand location, quantity and composition," said Papapolymerou, who is teamed with another Georgia Tech professor, John Cressler, and Ted Heath, a Georgia Tech Research Institute (GTRI) senior research scientist. "This mapping ability is very important because we need to know about ice accumulation, consistency and stability.”
Phased-array radar technology uses fixed, interconnected antenna elements to send and receive multiple radar signals almost simultaneously. This approach employs a technique called phase-shifting to electronically steer the radar-signal beam.
By contrast, a conventional radar antenna changes the direction of the signal beam mechanically; the antenna moves physically among set positions, sending and receiving signals at each position. The serial approach used by conventional radar generally offers slower and less-effective performance than the more parallel technique of phased-array radar.
The basic sub-array unit under development consists of a flat grid with eight antenna elements on a side – 64 elements in all. These sub-arrays, measuring about 8.5 by 7 inches, can be combined to create a far larger radar array capable of high-quality 3-D mapping.
The sub-arrays are constructed using polymers as the substrate, which is the board-like structure in which the electronics are embedded. Polymers have numerous advantages; robust and flexible, they are also low in cost and offer good electrical performance.
To date, the researchers have produced and successfully tested an eight-by-two-element sub-array mounted on a multi-layer substrate. This substrate consists of a layer of liquid crystal polymer (LCP), which is a robust organic polymer, and a layer of a composite material called Duroid.
The LCP/Duroid substrate houses integrated circuits made from silicon-germanium (SiGe). The SiGe chips transmit and receive the radar signals via the sub-array's multiple interconnected antenna elements.
The researchers chose silicon-germanium because it offers high-performance signal amplification that is also low in noise and in power consumption, said Cressler, who is a Ken Byers Professor in the School of Electrical and Computer Engineering. SiGe chips are also robust, low in cost and highly resistant to weather and to radiation encountered in space.
"Using silicon-germanium allows much higher levels of integration, which older radar systems don’t give you," Cressler said. "It enables you to go from a system which is much larger and more expensive, and less robust, to a chip that is only a few millimeters on a side and costs far less."
Silicon-germanium circuits also interface well with RF-MEMS systems, which are tiny micro-electromechanical devices capable of movement on a very small scale. The team is using RF-MEMS devices, embedded in the substrate, to perform two functions -- switching between the transmit and receive circuits, and activating phase-shifters that electronically guide the radar signals sent by the sub-array's 64 antenna elements.
Using MEMS devices for electro-mechanical switching results in less signal loss than integrating the transmit-receive switching function within a SiGe chip electronically, Cressler said. And while MEMS switching is a bit slower than a purely electronic approach, it offers both better signal performance and the ability to handle higher signal-output power.
The system under development uses the X band -- microwave frequencies between 8 and 12 gigahertz (GHz). This band is especially effective for scanning within ice and snow deposits and remotely mapping them in three dimensions.
GTRI's Heath and his team are developing the hardware that controls the electronic components, such as the field-programmable gate arrays used by the phase-shifters to electronically steer the signal beam. The GTRI team is also designing the power supplies required by the system.
In addition, the Georgia Tech team is using the radar range at GTRI's Cobb Country Research Facility for testing.
"GTRI is tasked with taking the silicon-germanium / MEMS transmit-receive elements and putting them into a functioning radar system," Heath said. "These back-end electronics supply the power to those chips, as well as provide the signal processing and conditioning that steer the signals, and the processing of the raw data coming back."
Papapolymerou added that this approach to phased-array technology is expected to have uses in a variety of defense and commercial applications.
This research was conducted under contract number NNX-08AN22G. Any opinions, findings and conclusions or recommendations expressed in this article are those of the researchers, and do not necessarily reflect the views of the National Aeronautics and Space Administration.
Technical Contact: John Papapolymerou (404-385-6004)(firstname.lastname@example.org).
John Toon | Newswise Science News
Illinois team finds Wigner crystal -- not Mott insulator -- in 'magic-angle' graphene
25.09.2018 | University of Illinois College of Engineering
Measuring Smallest Magnetic Fields in the Brain Using Diamond and Laser Technology
25.09.2018 | Fraunhofer-Institut für Angewandte Festkörperphysik IAF
Our brain is a complex network with innumerable connections between cells. Neuronal cells have long thin extensions, so-called axons, which are branched to increase the number of interactions. Researchers at the Max Planck Institute of Biochemistry (MPIB) have collaborated with researchers from Portugal and France to study cellular branching processes. They demonstrated a novel mechanism that induces branching of microtubules, an intracellular support system. The newly discovered dynamics of microtubules has a key role in neuronal development. The results were recently published in the journal Nature Cell Biology.
From the twigs of trees to railroad switches – our environment teems with rigid branched objects. These objects are so omnipresent in our lives, we barely...
The Fraunhofer FEP has been involved in developing processes and equipment for cleaning, sterilization, and surface modification for decades. The CleanHand Network for development of systems and technologies to clean surfaces, materials, and objects was established in May 2018 to bundle the expertise of many partnering organizations. As a partner in the CleanHand Network, Fraunhofer FEP will present the Network and current research topics of the Institute in the field of hygiene and cleaning at the parts2clean trade fair, October 23-25, 2018 in Stuttgart, at the booth of the Fraunhofer Cleaning Technology Alliance (Hall 5, Booth C31).
Test reports and studies on the cleanliness of European motorway rest areas, hotel beds, and outdoor pools increasingly appear in the press, especially during...
The building blocks of matter in our universe were formed in the first 10 microseconds of its existence, according to the currently accepted scientific picture. After the Big Bang about 13.7 billion years ago, matter consisted mainly of quarks and gluons, two types of elementary particles whose interactions are governed by quantum chromodynamics (QCD), the theory of strong interaction. In the early universe, these particles moved (nearly) freely in a quark-gluon plasma.
This is a joint press release of University Muenster and Heidelberg as well as the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt.
Then, in a phase transition, they combined and formed hadrons, among them the building blocks of atomic nuclei, protons and neutrons. In the current issue of...
Thin-film solar cells made of crystalline silicon are inexpensive and achieve efficiencies of a good 14 percent. However, they could do even better if their shiny surfaces reflected less light. A team led by Prof. Christiane Becker from the Helmholtz-Zentrum Berlin (HZB) has now patented a sophisticated new solution to this problem.
"It is not enough simply to bring more light into the cell," says Christiane Becker. Such surface structures can even ultimately reduce the efficiency by...
A study in the journal Bulletin of Marine Science describes a new, blood-red species of octocoral found in Panama. The species in the genus Thesea was discovered in the threatened low-light reef environment on Hannibal Bank, 60 kilometers off mainland Pacific Panama, by researchers at the Smithsonian Tropical Research Institute in Panama (STRI) and the Centro de Investigación en Ciencias del Mar y Limnología (CIMAR) at the University of Costa Rica.
Scientists established the new species, Thesea dalioi, by comparing its physical traits, such as branch thickness and the bright red colony color, with the...
21.09.2018 | Event News
03.09.2018 | Event News
27.08.2018 | Event News
26.09.2018 | Trade Fair News
26.09.2018 | Life Sciences
25.09.2018 | Health and Medicine