In recent years, the field of terahertz (THz) technologies has entered a phase of unprecedented interest and expansion. This frequency range, bridging the gap of the electromagnetic spectrum between electronics and photonics, offers emerging opportunities for new engineering paradigms. This emerging field has been recognized as of extreme importance for many scientific and commercial applications in future wireless, security, biology, astrophysics, materials, medicine, and environmental sensing. THz technologies can be applied not only in radio astronomy but also in the identification of chemical, physical, and biological agents (i.e. DNA molecules), as well as in imaging. Recent breakthroughs in millimeter-wave and THz developments have paved the way for novel research activities and technological developments, stimulated by the progressive advent of cost-effective components, circuits and systems for wide-ranging commercial applications.
An analogy of a prism at optical frequency is a frequency scanning antenna at THz which can be realized in the form of a reflectarray consisting of thousands of elements of about 0.2 mm by 0.2 mm each. Fine details with tight control of geometrical dimensions of each element require microfabrication in a cleanroom. In this example, the reflectarray has a scanning range of 30° when the frequency is varied from 200 to 300 GHz.