while watching the tom bearden videos posted by chris the other day. i got the concept of longitudinal waves, and phase conjugate waves. that led me to parametric amplifiers, devices developped in the late 1950s and the 60s and primarily used by the us military. they used nonlinear reactance ferite cores or non linear capacitance diodes called varactors. they are unusual in the sense that they amplify with very small current consumption by the amplifier, with infinite gain need a bit of tuning. the patents and papers i came across patents and papers that mention:
- two signals 180degrees out of phase
- ferite ring cores magnettically saturated with few turns opposing coils
- the concept of pumping signal
- and that they dont obey the concept of conservation of energy
Anyway take a look at the articles i linked , and in my opinion the varactors non linear performance has improved so much that this is the way to go. the non linear ones are now called abrupt and hyperabrupt varactors. the overunity aspect of these devices are not mentioned anywhere(duh!) but you can connect the dots yourself.
P.S: at first they used a spring inductor attached to a motor to vary the inductance mechanically to perform the parametric pumping.
look at these papers yourself and let me know what you think.
i will post more with commentary as i go deeper.