Non-foster circuit matching of a near-field resonant parasitic, electrically small antenna

Abstract

The impedance bandwidth of a near-field resonant parasitic (NFRP) element of an electrically small, metamaterial-inspired Egyptian Axe Dipole (EAD) antenna, can be altered significantly by embedding a non-Foster circuit element into it. The frequency agile behavior of the reactance component internal to the NFRP element of an EAD antenna with a center frequency of 300 MHz is established and a negative impedance converter (NIC) circuit is designed to mimic this behavior. Several other non-Foster circuits have been considered for the NIC implementation and will be discussed in our presentation. A Linvill-based design of the requisite NIC, which contains 4 bipolar junction transistors (BJTs), is presented here. ANSYS HFSS was used for the antenna simulation results; Agilent ADS was used for the circuit simulations. The co-designed, optimized results show an increase in the EAD fractional impedance bandwidth from 0.9% to 46.0%, a factor of over 50 times improvement.