Millimetre wave and Terahertz imaging technology refers to passive (or active) imaging in the millimetre and sub-millimetre range by using very sensitive radiometers (or radars). Millimeter wave imaging is useful for a wide variety of commercial applications such as aeronautic (near-all-weather vision landing), security (weapon detection), automotive (collision avoidance radars), and biomedical (tumor recognition, disease diagnosis, thermal burn imaging, recognition of protein structural states, detection/imaging of tooth decay). Regardless of the application, the availability of a low-cost imaging sensor with sufficient sensitivity is critical to the successful deployment of this technology. The two missing key technologies that will lead to the successful, wide spread application of mm-wave / submm-wave imaging are a) large format, low cost staring focal plane receiver arrays for passive imaging, and b) rapid electronic beam steering/forming combined with single/few channel radar front ends for active imaging.
Passive millimeter-wave images are created by measuring an antenna temperature map over the scene of interest using a very sensitive radiometer. The antenna temperature of the object depends on the noise radiated from the object. Hence the importance of the loss introduced by the systems frontend between an LNA and antenna which typically can be as high as 3dB. In order to enhance the systems performances this value need to be lowered. Antennas used in the state of the art imaging systems are bulky and expensive (horn antennas, linearly/Fermi taped slot antennas combined into 3D arrays).
The present project targets the enhancement of present solution by developing of low-loss high gain antenna array using a true planar topology, using high resistivity silicon bulk and surface micromachining. Using RF MEMS switches it may be possible to reduce these losses to around 1 dB which then would improve the over-all system performance. The use of low-loss MEMS switches can also for this kind of application enable more cost-effective architectures based on switched beam or electronic beam steering using passive sub-arrays. RF MEMS also has the potential to operate at frequencies well beyond 94 GHz:
For imaging applications there is a strong push towards higher frequencies in order to gain better angular resolution with moderate aperture diameters. Therefore the main objectives of the project can be summarized as: High gain membrane-supported antenna and antenna array design and optimization - integration of RF MEMS switches with antenna elements on the same thin dielectric membrane - hybrid integration of LNAs and Schottky diodes with the antenna front-ends on the same high-resistivity silicon chips. The expected result is to provide a technology process flow to implement novel, compact and high sensitivity millimeter wave imaging systems to advance the present capabilities in biomedical diagnosis and examinations