Arkansas Advances Radar Technology

A 3D rendering of The Long Range W-Band radar using power amplifier Monolithic Microwave Integrated Circuits (MMICs).

The pace of innovation in the automotive, biomedical, and aerospace industries would hardly be possible without advances in radar technology. From measuring the respiratory rates of patients in real time to detecting the occupancy levels inside industrial warehouses; the application space for radar systems is vast and continues to increase as the performance of radar systems improves.

High frequency radar systems are particularly advantageous and have recently become feasible due to advances in millimeter wave technology. The fine range resolution offered by these systems allows the position of an object to be calculated more precisely. Additionally, some electromagnetic waves at some higher frequencies suffer less loss in rain and other environmental conditions, which allows objects to be detected more reliably or at greater distances. Lastly, high frequency systems are typically smaller in size which allows them to be deployed on smaller, mobile systems.

While the design of circuits and processing techniques continue to be critical to the advancement of radar technology, the substrate in which the radar systems are constructed is becoming increasingly significant. One material that has received significant interest for radar and other technology is Low Temperature Cofired Ceramic (LTCC). Its ability to remove heat quickly, contribute to low loss for high frequency signals, and keep out contaminants make this material a prime candidate for high frequency, high power radar systems. Additionally, the processing method for this material allows components to be embedded into the substrate which allows integrated, high-density systems to be constructed.

Almost seven years ago the University of Arkansas began a partnership with Honeywell Federal Manufacturing & Technologies to conduct research in radar technology alongside several other universities. Alan Mantooth, distinguished professor and Samir El-Ghazaly, distinguished professor, of electrical engineering lead the project. Since then, the University of Arkansas has proceeded to produce significant work relevant to radar technology while leveraging its LTCC fabrication facilities. One such project is the modification of a K-Band Agricultural radar for the LTCC substrate.

The transmission structures on the original structure are redesigned to address the change in material properties while other design changes are made to mitigate defects that arise during the fabrication process. At its conclusion, this final agricultural system is expected to detect objects at larger distances than the original system due to the advantages offered by the LTCC substrate.

The K-Band agricultural radar fabricated in Low- Temperature Cofired Ceramic (LTCC).

The University of Arkansas has also leveraged its experience in high density electronics to design custom power supplies for high frequency radar systems. These power supplies dramatically reduce the size and weight of the radar systems which makes them a feasible payload for smaller aircraft systems with longer flights. Last year the University of Arkansas developed a power supply for a radar that measures depth and thickness of snow layers beneath the surface when mounted on an airplane. Now, the University of Arkansas research group is proceeding to design a more advanced power supply for a similar radar system.

The University’s past work on LTCC interconnects has also proceeded with a focus on Aerosol Jet Printed (AJP) transmission structures. The complex transmission structures that this method is capable of creating can ultimately lead to performance improvements due to high power handling and lower impedance mismatch in the electrical circuit. One featured application of these interconnects is currently being developed by the group with the integration of the W-Band power amplifier die onto an automotive radar circuit board. At high frequencies like those in the W-Band, interconnect method is increasingly important as losses are magnified along with dissatisfactory influences from neighboring components. This work will also lead to the range extension of the radar system and its repurposing of applications beyond vehicle detection.

The Honeywell Radar Consortium continues to be a highlight of the research environment at the University of Arkansas by illustrating the necessity for university collaboration with industry and one another. In year seven, the University of Arkansas has had several graduate and undergraduate students intern with Honeywell. Some of those students have gone on to join the company full time. In addition to the technical training that students gain in the laboratory environment, students gain exposure to the inner workings of a research program that contains budgeting and reporting. Just this year students delivered a half day training presentation which provided a crash course in electronic packaging and power supply design to Honeywell employees. A clear example of the beneficial relationship between academia and industry, this served as a milestone in the professional development of student engineers while providing a massive transfer of knowledge from academia to industry. The student research team at the University of Arkansas currently consists of student members Nathanial Shetters, Roberto Quezada, and Latarence Butts.