Power Transfer Theory on Linear Passive Two-Port Systems

Abstract

This paper theoretically revisits linear passive two-port systems from the viewpoint of power transfer. Instead of using the conventional S 21 magnitude, we propose generalizing the kQ product as a figure of merit for two-port performance evaluation. We explore three examples of power transfer schemes, i.e. inductive, capacitive, and resistive channels. Starting from their voltage-current equations, the kQ formula is analytically derived for each scheme. The resultant formulas look different in appearance but are all physically consistent with ωM/R, which stems from the original definition of kQ product in a primitive transformer. After comprehensively learning from the three examples, we finally extend the theory to a black-box model that represents any kind of power transfer channel. In terms of general two-port Z-parameters, useful mathematical expressions are deduced for the optimum load, input impedance, and maximum power transfer efficiency. We also supplement the theory with helpful graphics that explain how the generalized kQ behaves as a function of the circuit parameters.

Wireless Power Transmission Efficiency of Dipole Array Antenna using a Left-Handed Waveguide Slot Antenna as a Feeder

“…Fig. 4 shows the wireless power transmission efficiency obtained from the kQ product using S-parameter that were calculated by the method of moments electromagnetic field analysis [8], and Fig. 5 shows the maximum wireless power transmission efficiency.…”

“…In the case of left-handed waveguide, however, has large loss because of the long stub, and not enough consideration about wireless power transmission efficiency using the slotted left-handed waveguide as feeder, has been given. Therefore, in this study, the wireless power transmission efficiency [7] was obtained by using the electromagnetic field analysis using the moment method and the kQ product [8]. In this paper, in order to increase the power of the power receiving unit, the power receiving antenna is an array antenna composed of dipole antennas.…”

FDTD Analysis on WPT Efficiency Between Circuit-Shape Leaky Waveguide and 𝝀/2 Dipole Antenna for Snow Melting Application

“…From S-parameters simulated for 4 locations 1-4, 𝜂 and 𝜂 𝑚𝑎𝑥 were calculated [6] [7]. They are shown in Figure 8 for location 1, Figure9 for location 2, Figure 10 for location 3, and Figure 11 for location 4, respectively.…”

Null-free two-dimensional capacitive wireless power transfer based on inversion of electric field distribution

“…η max is calculated using Eqs. ( 5), (6), and ( 7) [11]. The calculation is repeated by moving the RX position in the longitudinal direction (paths A, B, and C) on electromagnetic software, as shown in Fig.…”