A Design Of Non-foster Reactance Components For Antenna Applications

With the development of the wireless communication and the dependence of highquality information, more and more requirements are put forward to the antenna. Antennaengineers not only have been trying to improve the antenna performance, but also havebeen researching the wideband matching technique between the antenna and the matchingcircuit. When matching Electrically Small Antenna (ESA), the Non-Foster circuit caneffectively break through the technology limits of low efficiency and narrow bandwidthin passive matching which achieved by negative impedance converter (NIC). This isbenefic for antenna in miniaturization and broadband. The thesis mainly studies theproperties of the Non-Foster reactance component and its applications. Its major workincludes the following aspects:1. Grounding non-foster reactance circuit which achieved by transistors is designedand studied. Firstly, SP simulation model is established and the relationship betweennegative reactance coefficients and components of the grounding non-foster circuit isobtained. Secondly, PB simulation model is established. The imaginary reactance ofelectrically small antenna is offset when the electrically small antenna is connected inparallel with the grounding non-foster circuit. Thirdly, analysis using reflectioncoefficient method indicates this grounding non-foster reactance circuit has a goodstability. At last, AC parameters and DC bias parameters of this circuit has been analyzed.The optimum AC parameters suitable for this circuit are confirmed. The influence of DCbias parameters on the circuit have been discussed.2. Floating non-foster reactance component circuit which achieved by transistors isdesigned and studied. Firstly, SP simulation model and PB simulation model areestablished, proven the feasibility of the theory. Secondly, the imaginary reactance ofelectrically small antenna is offset when the electrically small antenna is connected inseries with the floating non-foster circuit. Thirdly, electric performance parameters of thecircuit ports and transistors ports are analyzed using reflection coefficient method. Itconcludes that this floating non-foster reactance circuit has a good stability. At last, ACparameters and DC bias parameters of this circuit has been analyzed. The optimum ACparameters suitable for this circuit are confirmed. The influence of DC bias parameterson the circuit have been discussed.3. Non-foster reactance component circuit which achieved by operational amplifiersis designed and studied. Firstly, grounding non-foster reactance component circuit and floating non-foster reactance component circuit are designed with operational amplifiersas its core. The circuit is optimized and the potential unstable factors of the circuit areeliminated. Secondly, the equivalent model of the electrically small antennas is in parallelwith grounding non-foster circuit and series with floating non-foster circuit respectively.A good matching effect is obtained at2MHz-30MHz. Thirdly, the influence of thecomponents on the non-foster reactance circuit is simulated and analyzed. Finally, thegrounding non-foster reactance circuit is manufactured. The circuit is tested using themethod that positive capacitor is connected in parallel with the negative capacitor. Theresults show that the circuit can achieve a negative capacitance characteristics2MHz-30MHz.