Ultra-Wideband, Miniature Microstrip Antenna with High Dielectric Constant based on Non-Foster Circuit Matching

In this paper, a non-Foster circuit with a balun transformer is designed to match a high dielectric constant microstrip antenna. This circuit uses Linvill's floating negative impedance transformer, which generates negative impedance to offset the reactive component of the antenna and enhances the antenna's real resistance for improved matching. Simulation validation of the designed antenna and circuit is performed using HFSS and ADS. The microstrip antenna loaded with dielectric constant of 44 only has a relative bandwidth of 0.5%. With the help of non-Foster circuit matching, the relative bandwidth is increased to 55%, ranging from 440 MHz to 780 MHz, and a maximum gain enhancement of 11.7 dB is achieved. The overall volume of the microstrip antenna is 0.04λ×0.05λ×0.002λ, where λ is the wavelength at the lowest frequency.