Submillimeter radar using signals reflected from multiple angles

A method of using a submillimeter wavelength active radar system, the method comprising:

• illuminating a field of view using submillimeter radiation transmitted from a transmitter;
• receiving and downconverting signals from content in a field of view of the system, the downconverted signals corresponding to a given point in the field of view and having time varying amplitude and phase components which have a periodic component which is dependent on the content at the given point, the downconverted signals comprising signals from different illumination or receiving angles by having multiple illumination or receive positions, and
• processing the downconverted signals to determine information about the content from the periodic component and of using determined information from the signals from the two or more angles to determine location or orientation of the content,
• wherein the information comprises one or more effects selected from content flutter, speckle patterns characteristic of the content, and interference effects from thin layers in the content.

A submillimeter wavelength radar system comprising:

• a receiver configured to receive and downconvert signals from content in a field of view of the system, the downconverted signals corresponding to a given point in the field of view and having time varying amplitude and phase components which have a periodic component which is dependent on the content at the given point;
• and
• a processor arranged to determine information about the content from the periodic component,
• the radar system being arranged to obtain signals of the same points in the field of view from different illumination or receiving angles by having multiple illumination or receive positions, and
• the processor being arranged to use the determined information from the signals from the two or more angles to determine location or orientation of the content,
• wherein the processor comprises a part for discriminating the information by applying one or more operators to the received signal to extract spatial or temporal features of spectra of the received signal, and
• wherein the extracted features comprise one or more effects selected from content flutter, speckle patterns characteristic of the content, and interference effects from thin layers in the content.