Multiport Non-Foster Loading Matching Technique for Wideband Antenna with Stable Omnidirectional Pattern Using the Theory of Characteristic Modes

Abstract

Multiport reactive loading matching technique for designing wideband monopole antenna with stable omnidirectional pattern is proposed in this paper using the theory of characteristic modes. Firstly, a systematic framework is presented to calculate the reactive loadings, which are combination of Foster and non-Foster elements. Secondly, the characteristic modes of dipole are analyzed to demonstrate the radiation pattern of dipole antenna. When one more load is added at each arm of dipole, the dipole cannot suppress the high order modes to realize omnidirectional pattern. Finally, a monopole antenna with three reactive loads is presented to realize wide bandwidth (100-400 MHz) with stable omnidirectional patterns.