Overview

A compact definition of radio-frequency engineering states that this discipline deals with methods and techniques for the generation, processing, transmission, and technical applications of electromagnetic waves. Some decades ago, radio-frequency engineering covered all aspects of circuits and systems for wireless communications and other radio frequency applications. Today, methods of radio-frequency engineering are necessary in a wide area of electrical and electronic engineering. Radio-frequency engineering has developed from a product-oriented discipline towards a method-oriented field, providing the fundamentals for dealing with high frequencies in all branches of electrical and electronic engineering.

Radio-frequency engineering is the discipline dealing with the technical applications of electromagnetic fields. It is based on Maxwell's theory of electromagnetic fields. Table 1.1 illustrates the history of the field theory from Huygens to Maxwell. In 1690, Christian Huygens published his Trait de la Lumi re and presented there basic concepts of a wave theory of light [1]. Huygens formulated the principle that each point of an intermediate plane inserted in a propagating wave may be considered as the origin of a spherical wave. The secondary waves are determined by the envelopes of all these spherical waves.