**Authors:** L. Batel, L. Rudant, J-F. Pintos, K. Mahdjoubi

**Source:** FERMAT,Volume 12,Communication,Nov-Dec,2015

**Abstract:** Performance characteristics of Electrically Small Antennas are limited by fundamental physics. Using
Non-Foster elements into antennas structures appears like an opportunity to overshoot those limits. In this paper, a
Negative Impedance Converter circuit is designed for antenna applications at 868 MHz. These active circuits, that
produce Non-Foster negative capacitance or inductance, are known as sensitive circuits due to their nonlinearities
that can produce instabilities. Thus, designing Negative Impedance Converters at Ultra High Frequency bands
becomes quite challenging. Accurate design is strongly recommended to predict the final behavior of the circuit. The
Negative Impedance Converter sensitivity is investigated with respect to Printed Circuit Board design through both
simulation and measurement results.

**Index Terms:** Negative Impedance Converter, Non-Foster elements, negative impedance, electrically small
antennas

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