Introduction to microwaves

It is generally accepted that the microwave domain covers a certain part of the electromagnetic (EM) spectrum, from sub-meter to millimeter or even sub-millimeter waves, and corresponds to frequency bands from 100 MHz to 1,000 GHz, i.e. from 3 m to 0.3 mm.

However, it is possible to establish another dividing line with the other fields of electronics by considering that circuit design and modeling fall within the microwave domain when propagation and radiation phenomena are explicitly taken into account, which is generally not the case in the other fields of electronics. There is in fact no fixed boundary between these fields, with the importance of these two phenomena of propagation and radiation in relation to the operation of the device or system under study serving in practice as a criterion for being placed in the microwave field or not.

At lower frequencies, the analysis and design tools applicable to radiation and propagation are similar to those used in the microwave field, but are often distinguished by application specializations. At higher frequencies, from infrared to visible waves, optics tools are often well suited.

This article presents the main fields of research structuring the very important evolution of the microwave field, namely the synthesis of new nanomaterials accompanied by the design and production of artificial electromagnetic materials and the emergence of nanotechnologies.

The emergence of nanotechnologies has led to the rediscovery of the field of superconductivity (new functions resulting from the realization of Josephson junctions using superconductors at high critical temperatures) and the field of microwave optoelectronics.

The last paragraph is devoted to identifying the main applications of these technologies in the field of components and systems.

A glossary of terms is provided at the end of the article.