Electrically Small Rectangular Microstrip Patch Antenna with Non-Foster Feeding Technique

Electrically small antennas (ESAs) are characterized by low input resistance and comparatively high input reactance which makes them difficult to match for practical operations. In this paper a Negative Impedance Converter (NIC) based negative inductor is used to improve the matching and obtain a degree of miniaturization of a rectangular microstrip patch antenna, electrically small up to 600 MHz. The antenna was initially designed at 800MHz, and later with the incorporation of the NIC circuit, effective cancellation of reactance could be achieved at a lower frequency of 393MHz, leading to miniaturization of the system. Both the NIC and antenna structures are fabricated and tested in the laboratory. The simulated and the measured results are compared and analyzed in this article.