Millimeter-wave Imaging and Sensors

Millimeter wave and THz imaging are proving to be valuable adjuncts to visible, IR, and X-ray imaging systems. The advantage of millimeter wave radiation is that, in addition to clear weather day and night operation, it can also be used in low visibility conditions such as in smoke, fog, clouds and even sandstorms. In this way, millimeter wave imaging expands our vision by letting us "see" things under poor visibility conditions. With this extended vision ability, a wide range of military imaging missions would benefit, such as surveillance, precision targeting, navigation, search and rescue. In the commercial realm, aircraft landing aids, airport operations, and highway traffic monitoring in fog can also benefit from MMW imaging. For security concerns, concealed weapon and explosives detection in airports and other locations can be aided with several passive as well as active MMW imaging techniques. In addition, millimeter wave imaging is also applied in remote sensing, radio astronomy and plasma diagnostics to visualize objects that cannot be directly seen. Millimeter wave imaging can basically be divided into two separate approaches: passive millimeter wave imaging and active millimeter wave imaging. Passive millimeter wave systems directly detect the natural radiation from the objects or the reflection from the environment. The concept is analogous to radiometry. Active millimeter wave imaging systems first illuminate the objects and subsequently detect the reflected millimeter waves. Many active imaging systems are essentially radar based. The millimeter wave and THz imaging research areas at the DMRC include:

  • Planar Schottky diode mixer arrays
  • Planar antennas
  • Frequency selective surfaces
  • Phased antenna arrays (PAAs)

Recent Projects

  • Passive radiometric electron cyclotron emission imaging (ECEI) arrays [PDF]
  • Electronically controlled beam shaping and steering [PDF]
  • Mini-lens based imaging arrays [PDF]
  • Notch filters [PDF]