More work on related work section

paper/paper.bib

@@ -303,6 +303,23 @@
   file = {/home/jaseg/Zotero/storage/PT8K829W/Bartusek and Khurana - 2023 - Cryptography with Certified Deletion.pdf}
 }
 
+@article{batraEffectFerriteAddition2015,
+  title = {Effect of Ferrite Addition above the Base Ferrite on the Coupling Factor of Wireless Power Transfer for Vehicle Applications},
+  author = {Batra, T. and Schaltz, E. and Ahn, S.},
+  date = {2015-05-07},
+  journaltitle = {Journal of Applied Physics},
+  volume = {117},
+  number = {17},
+  pages = {17D517},
+  issn = {0021-8979, 1089-7550},
+  doi = {10.1063/1.4919039},
+  url = {https://pubs.aip.org/jap/article/117/17/17D517/387226/Effect-of-ferrite-addition-above-the-base-ferrite},
+  urldate = {2024-10-30},
+  abstract = {Power transfer capability of wireless power transfer systems is highly dependent on the magnetic design of the primary and secondary inductors and is measured quantitatively by the coupling factor. The inductors are designed by placing the coil over a ferrite base to increase the coupling factor and reduce magnetic emissions to the surroundings. Effect of adding extra ferrite above the base ferrite at different physical locations on the self-inductance, mutual inductance, and coupling factor is under investigation in this paper. The addition can increase or decrease the mutual inductance depending on the placement of ferrite. Also, the addition of ferrite increases the self-inductance of the coils, and there is a probability for an overall decrease in the coupling factor. Correct placement of ferrite, on the other hand, can increase the coupling factor relatively higher than the base ferrite as it is closer to the other inductor. Ferrite being a heavy compound of iron increases the inductor weight significantly and needs to be added judiciously. Four zones have been identified in the paper, which shows different sensitivity to addition of ferrite in terms of the two inductances and coupling factor. Simulation and measurement results are presented for different air gaps between the coils and at different gap distances between the ferrite base and added ferrite. This paper is beneficial in improving the coupling factor while adding minimum weight to wireless power transfer system.},
+  langid = {english},
+  file = {/home/jaseg/Zotero/storage/YYVWKXCV/Batra et al. - 2015 - Effect of ferrite addition above the base ferrite .pdf}
+}
+
 @incollection{baumMozMathbbArella2022,
   title = {Moz\$\$\textbackslash mathbb \{\vphantom\}{{Z}}\vphantom\{\}\_\{2\textasciicircum k\}\$\$arella: {{Efficient Vector-OLE}} and {{Zero-Knowledge Proofs}} over \$\$\textbackslash mathbb \{\vphantom\}{{Z}}\vphantom\{\}\_\{2\textasciicircum k\}\$\$},
   shorttitle = {Moz\$\$\textbackslash mathbb \{\vphantom\}{{Z}}\vphantom\{\}\_\{2\textasciicircum k\}\$\$arella},
@@ -2421,6 +2438,25 @@
   file = {/home/jaseg/Sync/Research/Zotero/2011_Lee et al_Printed Spiral Winding Inductor With Wide Frequency Bandwidth.pdf}
 }
 
+@article{leeSimpleWirelessPower2017,
+  title = {A {{Simple Wireless Power Charging Antenna System}}: {{Evaluation}} of {{Ferrite Sheet}}},
+  shorttitle = {A {{Simple Wireless Power Charging Antenna System}}},
+  author = {Lee, Woncheol and Hong, Yang-Ki and Park, Jihoon and Lee, Jaejin and Baek, In-Seung and Hur, Nam-Pal and Seong, Won-Mo and Park, Seong-Ook},
+  date = {2017-07},
+  journaltitle = {IEEE Transactions on Magnetics},
+  volume = {53},
+  number = {7},
+  pages = {1--5},
+  issn = {1941-0069},
+  doi = {10.1109/TMAG.2017.2676099},
+  url = {https://ieeexplore.ieee.org/document/7867861/?arnumber=7867861},
+  urldate = {2024-10-30},
+  abstract = {We report a simple wireless power charging (WPC) antenna system (50 mm \textbackslash times40 mm \textbackslash times0.1 mm) for use in simulating power transfer efficiency ( \textbackslash eta ) with and without ferrite and a metallic object (battery case), thereby identifying suitable magnetic parameters and ferrite sheet thickness. The simulation results suggest that magnetic loss tangent (tan \textbackslash delta \textsubscript{\textbackslash mu } ) and permeability ( \textbackslash mu ' ) need to be less than 0.05 and higher than 125 at 13.56 MHz, respectively, to achieve at least 75\% of the transfer efficiency ( \textbackslash eta \_\textbackslash mathrm max ) of the WPC antenna without ferrite and the metallic object. Accordingly, we have fabricated NixZn0.85–xCu0.15Fe2O4 (x = 0.32 – 0.38) spinel ferrites using a one-step sintering process and obtained relatively high \textbackslash mu ' of 169 and low tan \textbackslash delta \textsubscript{\textbackslash mu } of 0.1 with a nickel (Ni) concentration of 0.38. This magnetic loss is still too high to achieve 75\% of the \textbackslash eta \_\textbackslash mathrm max value. In order to further reduce the magnetic loss, a two-step sintering process was used. The two-step sintered Ni0.38Zn0.47Cu0.15Fe2O4 shows \textbackslash mu ' of 132 and a tan \textbackslash delta \textsubscript{\textbackslash mu } of 0.03 at 13.56 MHz, respectively. Therefore, this ferrite meets criteria identified by the transfer efficiency simulation and is a good candidate for 13.56-MHz wireless power transfer charging antenna system. In addition, our designed WPC system is capable of evaluating other magnetic materials that are suitable for WPC antenna applications.},
+  eventtitle = {{{IEEE Transactions}} on {{Magnetics}}},
+  keywords = {Antennas,Ferrites,Magnetic losses,Magnetic noise,Ni–Zn–Cu ferrite,Nickel,Permeability,Powders,power transfer efficiency,wireless power charging (WPC) system},
+  file = {/home/jaseg/Sync/Research/Zotero/2017_Lee et al_A Simple Wireless Power Charging Antenna System.pdf;/home/jaseg/Zotero/storage/S7MHYEYX/7867861.html}
+}
+
 @article{lellaSecurityQuantumKey2023,
   title = {On the {{Security}} of {{Quantum Key Distribution Networks}}},
   author = {Lella, Eufemia and Schmid, Giovanni},
@@ -2932,6 +2968,24 @@
   file = {/home/jaseg/Zotero/storage/YL2WRUTZ/Müller - 2016 - Wiring the World The Social and Cultural Creation.pdf}
 }
 
+@article{mumbyDielectricPropertiesFR41989,
+  title = {Dielectric Properties of {{FR-4}} Laminates as a Function of Thickness and the Electrical Frequency of the Measurement},
+  author = {Mumby, Stephen J. and Yuan, Jih},
+  date = {1989-03},
+  journaltitle = {Journal of Electronic Materials},
+  shortjournal = {J. Electron. Mater.},
+  volume = {18},
+  number = {2},
+  pages = {287--292},
+  issn = {0361-5235, 1543-186X},
+  doi = {10.1007/BF02657420},
+  url = {https://link.springer.com/10.1007/BF02657420},
+  urldate = {2024-10-30},
+  abstract = {The relationship between the dielectric properties (dielectric constant, e\textasciitilde am,and loss factor, e\textasciitilde m) and thickness of FR-4 laminates was investigated. Thickness variations for laminates reinforced by the same style and number of plies of glass cloth were predominantly due to differences in the resin content. At each measurement frequency, values of both el"mand e]'m were found to vary in an approximate linear manner with changes in the volume fraction of resin, Vr\textasciitilde n. An empirical equation was derived that gives the dielectric constant of an FR-4 laminate, el'm, as a function of the volume fraction of resin, Vr\textasciitilde n, and the frequency at which the measurement was performed (between 1 kHz and 1 GHz). An alternative expression was also determined that permits the calculation of e\textasciitilde. in the same frequency range from just the dielectric thickness of the laminate, providing the effective thickness of the reinforcement is known. The effective thickness of one style of glass cloth (2116) was experimentally determined to be 1.6 mils/ply. Effective thicknesses of most other common woven glass reinforcements used in FR-4 laminates were calculated and tabulated. The empirical relationships should be a valuable aid to electrical designers and others who need to know the frequency dependence of the dielectric properties of FR-4 laminates having different glass-to-resin ratios.},
+  langid = {english},
+  file = {/home/jaseg/Zotero/storage/9MA5VBJY/Mumby and Yuan - 1989 - Dielectric properties of FR-4 laminates as a funct.pdf}
+}
+
 @inproceedings{muraliContinuousAuthenticationUsing2023,
   title = {Continuous {{Authentication Using Human-Induced Electric Potential}}},
   booktitle = {Annual {{Computer Security Applications Conference}}},
@@ -4587,6 +4641,19 @@
   file = {/home/jaseg/Sync/Research/Zotero/Zhang et al_2015_Robust counterfeit PCB detection exploiting intrinsic trace impedance variations.pdf;/home/jaseg/Zotero/storage/GS9H6QT9/7116294.html}
 }
 
+@online{zhaoDesignOptimizationLitzWire2023,
+  title = {Design and {{Optimization}} of {{Litz-Wire Planar Spiral Coil}} for {{Inductive Power Transfer Application}}},
+  author = {Zhao, Weihao and Peng, Yingzhou and Zhan, Shen and Wang, Huai},
+  date = {2023-04-07},
+  doi = {10.36227/techrxiv.22491235.v1},
+  url = {https://www.techrxiv.org/doi/full/10.36227/techrxiv.22491235.v1},
+  urldate = {2024-10-30},
+  abstract = {Litz wire planar spiral coils are widely used in inductive power transfer systems due to low power loss in high-frequency operation and low profile. However, the complicated structure of the litz wire coil imposes difficulties in estimating the frequency-dependent resistance and quality factor accurately. In this work, we present an 2D analytical model for calculating the frequency-dependent resistance and quality factor of multi-coil inductive power transfer systems based on superposition of different loss effects. Its accuracy is validated with multiple coils and litz wires over wide frequency range. Meanwhile, a fast and accurate multi-objective optimization method is developed to improve the product quality factor and coupling factor. From the optimization results, there are five factors affecting the quality factor and coupling factor. A set of design guidelines is proposed to cope with these design factors. The final prototypes show 33\textbackslash\% increase in quality factor and 23\textbackslash\% improvement in coupling factor compared with the state-of-the-art designs. Meanwhile, a 30W, 500kHz inductive power transfer system is designed with 91\textbackslash\% peak efficiency.},
+  langid = {english},
+  pubstate = {prepublished},
+  file = {/home/jaseg/Zotero/storage/ZAQTS252/Zhao et al. - 2023 - Design and Optimization of Litz-Wire Planar Spiral.pdf}
+}
+
 @inproceedings{zhouPPMLACHighPerformance2022,
   title = {{{PPMLAC}}: High Performance Chipset Architecture for Secure Multi-Party Computation},
   shorttitle = {{{PPMLAC}}},

paper/paper.tex

@@ -100,6 +100,9 @@ air core inductors that were commonly used in old radio sets.
 
 \section{Related Work}
 
+% TODO cite \cite{fanSimultaneousWirelessPower2024} (rotating coupling)
+% TODO cite \cite{mullenEffectMisalignmentInductive} (misaligned coils)
+
 \subsection{A Short Historical Diversion on Basket-Woven Air Coils}
 
 Since the early days of radio engineering, the parasitic capacitance of inductors has been a point of
@@ -115,10 +118,18 @@ compactness and leakage inductance, but in turn gives rise to increased distribu
 
 Back then, a number of ways were devised to decrease distributed capacitance in multilayer inductors. These methods can
 be divided into two general categories: Optimizing the connecting order of turns to minimize the voltage differential
-between adjacent turns, and optimizing the winding schema to increase the separation between turns. The main technique
-in the first category concerns winding the turns of a cylindrical multilayer inductor not layer by layer, but instead
-layering them diagonally, effectively connecting adjacent turns in a diagonal zigzag pattern. Then as now, this
-technique was only feasible for winding by hand, and could not be executed reliably by machine.
+between adjacent turns---a technique that is still used to this day\cite{lopeFirstSelfResonant2021}, and optimizing the
+winding schema to increase the separation between turns. The main technique in the first category concerns winding the
+turns of a cylindrical multilayer inductor not layer by layer, but instead layering them diagonally, effectively
+connecting adjacent turns in a diagonal zigzag pattern. Then as now, wound inductors applying this technique were not
+feasible to manufacture reliably by machine, but the technique can be closely replicated in PCB inductors as shown in
+\textcite{leePrintedSpiralWinding2011a}. The main limiting factors in a PCB implementation are the requirement for a
+large number of vias inside the inductor's turns limiting the achievable turn count\footnotes{In PCBs, as opposed to
+ICs, vias limit the achievablie turn count when they need to be placed in-line inside the turns as opposed to on the
+inside or outside because a PCB's minimum trace/space widths are usually much smaller than the smallest feasible via,
+consisting of a minimum-size drill surrounded by a minimum-size annular ring.} and increasing ESR through the thin trace
+sections that are necessary to accomodate the via structure, as well as the layer pairing limitations when blind vias
+are used in multilayer PCBs.
 
 \begin{figure}
     \begin{center}
@@ -161,6 +172,7 @@ condition between the number of turns and the number of inversions within each t
 inductors below, although in contemporary literature, this condition is never explicitly stated
 \cite{eppenAnforderungenEinzelteileRundfunkempfanger1927, kleinSpulenUndSchwingungskreise1941,
 wiggeRundfunktechnischesHandbuch1930}.
+% TODO cite \cite{querfurthCoilWindingDescription1954}
 
 \subsection{PCB inductor design for wireless power transfer}
 
@@ -181,9 +193,10 @@ lower than in wire-wound inductors. Second, due to a PCB's copper layers being t
 substrate, PCB inductors tend to have poor DC resistance. A PCBs' thin but wide trace cross-section helps with
 skin effect compared to a solid conductor. However, PCBs can still not approach the performance of litz wire used in
 high-frequency WPT coils, which commonly use wire diameters in the tens of micrometer
-range\cite{zhaoDesignOptimizationLitzWire2023}. \textcite{lopeFrequencyDependentResistancePlanar2014} propose a
-mitigation that aims to emulate a litz wire's structure in large, high-current PCB inductors, but their mitigation is
-heavily limited by the structure size achievable in common PCB manufacturing processes.
+range\cite{zhaoDesignOptimizationLitzWire2023}. \textcite{lopeFrequencyDependentResistancePlanar2014} and
+\textcite{nomotoSplittingConductorsCoils2024} propose a mitigation that aims to emulate a litz wire's structure in
+large, high-current PCB inductors, but their mitigation is heavily limited by the structure size achievable in common
+PCB manufacturing processes\cite{nguyenReviewComparisonSolid2020}.
 
 A further factor that limits the high-frequency performance of PCB inductors is distributed capacitance. Not only do
 large air coils exhibit more parasitic capacitance than much smaller ferrite-core inductors simply due to their size,
@@ -195,8 +208,9 @@ a pure air-core inductor.
 \subsection{Twisted Inductors in RFIC Design}
 
 The simplest twisted inductor as shown below with $k=1$ inversion corresponds to the counterwound scheme that is
-commonly used for two-layer planar inductors, and which has been used with planar coils for more than a
-century\cite{flemingPrinciplesElectricWave1910}.
+commonly used for two-layer planar
+inductors\cite{lopeFirstSelfResonant2021,sproHighVoltageInsulationDesign2021,leePrintedSpiralWinding2011a}, and
+which has been used to stack planar coils for more than a century\cite{flemingPrinciplesElectricWave1910}.
 
 \subsection{Inductive Wireless Power Transfer in Practice}