Source-linked AI summary
Beyond the Bode-Fano Bound: Wideband Impedance Matching for Short-Pulses using Temporal Switching of Transmission-Line Parameters
Amir Shlivinski, Yakir Hadad
TL;DR
Passive, linear time-invariant matching faces a bandwidth–efficiency tradeoff, especially for highly dispersive loads and large impedance contrasts. The paper switches transmission-line parameters over time and reports efficient matching beyond the Bode-Fano bound for short pulses.
Problem
The Bode-Fano criterion constrains matching efficiency and bandwidth in passive, linear time-invariant networks, particularly challenging for highly dispersive loads and high source-load impedance contrast.
Source: p. 1Method
The approach switches transmission-line parameters between two states and optimizes their normalized values to maximize matching efficiency under a switching-energy constraint.
Source: pp. 1, 3Results
Temporal switching significantly increases transmission efficiency over the non-switching case, especially at high impedance contrast, and can exceed the Bode-Fano bound.
Source: pp. 1, 3, 4Takeaways & Limitations
The approach supports efficient, minimally distorted matching for finite-duration signals, including challenging high-contrast and highly dispersive cases.
Source: pp. 4–5The paradigm is suitable only for finite-duration signals; time-variant matching for time-harmonic signals remains an open question.
Source: p. 5
Abstract
from arXiv · showhide
Impedance matching is one of the most important practice in wave engineering as it enables to maximize the power transfer from the signal source to the load in the wave system. Unfortunately, it is bounded by the Bode-Fano criterion that states, for any passive, linear and time-invariant matching network, a stringent tradeoff between the matching-bandwidth and efficiency; implying severe constraints on various electromagnetic and acoustic wave systems. Here, we propose a matching paradigm that overcome this issue by using a temporal switching of the parameters of a metamaterial-based transmission-line, thus revoking the time-invariance assumption underlying the Bode-Fano criterion. Using this scheme we show theoretically that an efficient wideband matching, beyond Bode-Fano bound, can be achieved for short-time pulses in challenging cases of very high contrast between the load and the generator impedances, and with significant load dispersion; situations common in e.g., small antennas matching, cloaking, with applications for ultra-wideband communication, high resolution imaging, and more.