%0 Electronic Article
%A A.A. Muller
%+ Microwave Applications Group, iTEAM, Universidad Politehnica de Valencia, Valencia, Spain
%A S. Lucyszyn
%+ Department of Electrical and Electronic Engineering, Imperial College London, Exhibition Road, London, SW7 2AZ, United Kingdom
%K driving-point reactance
%K network theory
%K driving-point susceptance
%K negative inductance
%K reactive Foster network
%K capacitance element
%K frequency gradient
%K nonFoster passive network
%K positive inductance
%K driving-point immittance
%X The mathematical concept of strongly real functions of positive and negative types is introduced to network theory for the first time. The driving-point reactance/susceptance of a pure Foster network, made up of only ideal positive inductance and capacitance elements, is a strongly real function of real frequency of positive type. As a corollary, for a pure non-Foster network made up of only ideal negative inductance and capacitance elements, the driving-point reactance/susceptance is a strongly real function of real frequency of negative type. It is shown that a condition for a purely reactive passive network to exhibit a positive or negative reactance/susceptance-frequency gradient is that the driving-point immittance should have alternating poles and zeroes lying on the real frequency axis. Finally, it is shown that either purely Foster or non-Foster networks can be constructed by combining ideal Foster and non-Foster reactive elements.
%@ 0013-5194
%T Properties of purely reactive Foster and non-Foster passive networks
%B Electronics Letters
%D November 2015
%V 51
%N 23
%P 1882-1884
%I Institution of Engineering and Technology
%U http://digital-library.theiet.org/;jsessionid=41wio3s0ueve6.x-iet-live-01content/journals/10.1049/el.2015.1429
%G EN