Millimeter and THz waves are electromagnetic waves ranging from 30 to 300 GHz, and from 300 GHz to 10 THz, respectively. This frequency range offers high bandwidth and directivity in communication and navigation systems, higher resolution in ranging applications (e.g. radar and non-destructive testing), and a good compromise between resolution and penetration depth for detection of objects, undetectable in the infrared or visible spectrum. As various materials, including biomaterials, exhibit a pronounced spectral footprint in this spectrum, this offers also unique properties for the development of bio-sensor systems.