2 Sources
Confidence: A = established reference / primary source, B = museum or collector record, C = forum or informal, K = from background knowledge, not yet checked against the original.
2.1 Web sources
| # | Source | Used for | Conf. |
|---|---|---|---|
| 1 | Wikipedia: Basket winding | definition, \(\theta \to 90^\circ\), proximity effect, parasitic capacitance, > 50 kHz, Litz wire, cotton insulation | B |
| 2 | Radiomuseum: De Forest coils and coupler LC-100 | 1919, Coto-Coil manufacture | B |
| 3 | California Historical Radio: De Forest Adjustable Coils (PDF) | Duo-Lateral, “Ultra Honeycomb”, Armstrong usage | B |
| 4 | Radiomuseum: Branston Honeycomb Inductance Coils | licensed copies, 1922–25, 25–1500 turns | B |
| 5 | Ingenium Canada: Coil, radio | patent date 21 June 1920 on label | B |
| 6 | Radiomuseum forum: Huth Steckspule | German terms (Korbspule, Korbbodenspule, Flachspule), honeycomb ≈ airy Kreuzwickel | C |
| 7 | Radiomuseum: Wendte Universalspule | 1924 plug-in coil | B |
| 8 | Wikimedia: Spider coil | odd number of tabs | C |
| 9 | boatanchors list, Nov 2010 | 9/11/13-slot forms | C |
2.2 Literature (confidence K)
Wheeler’s inductance formulas (Wheeler 1928), Medhurst’s self-capacitance data (Medhurst 1947), and the differential-form notation (Frankel 2011; Bossavit 1998).
2.3 Own verification
On 2026-11-14 a brute-force Python check confirmed Theorem 1.1 and Corollary 1.1 for \(N = 3\ldots15\) and every \(m\). The Wheeler and Medhurst example values were recomputed.
References
Bossavit, Alain. 1998. Computational Electromagnetism: Variational
Formulations, Complementarity, Edge Elements. Academic Press.
Frankel, Theodore. 2011. The Geometry of Physics: An
Introduction. 3rd ed. Cambridge University Press.
Medhurst, R. G. 1947. “H.f. Resistance and Self-Capacitance of
Single-Layer Solenoids.” Wireless Engineer 24.
Radiomuseum.org. n.d. Huth: Steckspule. Radiomuseum.org forum.
Accessed November 14, 2026. https://www.radiomuseum.org/forum/huth_steckspule.html.
Wheeler, Harold A. 1928. “Simple Inductance Formulas for Radio
Coils.” Proceedings of the Institute of Radio Engineers
16 (10): 1398–400.
Wikipedia contributors. n.d. Basket Winding. Wikipedia.
Accessed November 14, 2026. https://en.wikipedia.org/wiki/Basket_winding.