Equivalent circuit of a loop and load in a system of N coupled loaded loops. 22 Summations indicate the coupling factors between the loop and the remaining loops.
Extracted parameters of effective medium comprising infinite loaded loops corresponding to different spacing. (a) Non-Foster loading medium, (b) passive loading medium.
Equivalent circuit of a single loop with non-Foster load. The non-Foster circuits are obtained as the output of a noiseless NIC network terminated in a parallel positive RLC load ZN . The impedance looking into the NIC output would ideally be . Shaded components indicate Johnson-Nyquist noise sources.
The power spectral density (log-scale) of noise from a single non-Foster loaded loop, as compared to a passive structure with different types of loads. (a) Three-dimensional plots of the PSD of the active loop with the NIC load inductance LL changing from 0 nH to −50 nH while it varies from 0 nH to +50 nH for the positive RLC case, however having no impact on the positive C case. (b)Two-dimensional plots of the PSDs under different loading conditions, the negative inductance is varied from the stable to unstable cases.
The PSD of the noise in one-dimensional infinitely periodic loop arrays with different spacings. The spacing is varied from 5 mm to 20 mm. (a) The active media consist of periodic axial non-Foster loaded loops, where each load is defined as a parallel-RLC circuit with , and (b) The passive media consist of loops where the loads are replaced by positive capacitances .
The PSD of the noise in multi-dimensional infinitely periodic loop arrays, as compared to the single unit case. The 1D arrays consist of periodic coaxial loops with periodicity of 10 mm in the x direction, while the 2D arrays have additional coplanar periodicity (25 mm) in the y direction. The addition of coplanar periodicity (25 mm) in the z direction results in the 3D array case. (a) Active medium consists of non-Foster loaded loops. (b) Passive medium consists of loops where the loads are replaced by positive capacitances.
The PSD of the noise at the central element of a finite 1D loop array, as compared to the single unit and the infinite cases. The lattice spacing is 10 mm, and the number of elements varies from 11 to 21. (a) Active medium consists of non-Foster loaded loops. (b) Passive medium consists of loops where the loads are replaced by positive capacitances.
A system using a single active loop to connect a source Rsource to a load Rload . As discussed before, the active load is a non-Foster element ZL generated from the NIC, and equivalent to a parallel negative RLC circuit (ZL = RL ||LL ||CL ).
(a) The noise figure of the system consisting of a single non-Foster's loaded loop, as compared to the passive case. As proposed before, we take the same definitions for the loop and the loads, but vary the load inductance from to . (b) The contrast between the noise figure and the gain of the network for the actively loaded system with discrete load inductances , and .
A system using a 1D active loop array to connect a source and a load.
The noise figure of one-dimensional non-Foster loaded loop arrays. (a) and (b) correspond, respectively, to different distances between neighboring loops and different load inductances.
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