Most antenna engineers are likely to believe that antennas are one technology that is more or less impervious to the rapidly advancing semiconductor industry. However, as demonstrated in this lecture, there is a way to incorporate active components into an antenna and transform it into a new kind of radiating structure that can take advantage of the latest advances in analog circuit design. The approach for making this transformation is to make use of non-Foster circuit elements in the matching network of the antenna. By doing so, we are no longer constrained by the laws of physics that apply to passive antennas. However, we must now design and construct very touchy active circuits. This new antenna technology is now in its infancy. The contributions of this lecture are (1) to summarize the current state-of-the-art in this subject, and (2) to introduce some new theoretical and practical tools for helping us to continue the advancement of this technology.

Inhalt
Motivation for A New Kind of Radiating Structure/ Electrically Small Antennas/ Foster's Reactance Theorem and Non-Foster Circuit Elements/ Basic Concepts of Matching and BodeFano Limit/ Two-Port Model of AN Antenna/ Performance of ESA with Traditional Passive Matching Network/ Performance of ESA with Ideal Non-Foster Matching Network/ Basics of Negative Impedance Converters (NICS)/ Simulated and Measured NIC Performance/ Simulated Performance of ESA with A Practical Non-Foster/ Matching Network/ Conclusions/ References.