Wideband miniaturized antenna with external Non-Foster circuit

A miniaturized antenna using a matching circuit with Non-Foster elements is described. Such active external matching circuit allows a commercial antenna whose frequency range is 950-1260 MHz to operate at lower frequencies (about 125 MHz) with a relative bandwidth of 40%. Analytical study was used to design the active circuit and then to implement it. Simulation and measurement results show similar broad bandwidth (50 MHz) around operating frequency of 125 MHz with good stability. This study shows that Non-Foster circuit can be successfully used to overcome the fundamental limitations of electrically small passive antennas.