10 ms·
Oliver Heaviside and the theory of transmission lines (2021)
- roelschroeven 2y agoOne of the diagrams has the text "40 sections elk 100 m long". "Elk" (or "elke", depending on grammatical gender) is Dutch for "each", so it looks like a small oversight in translation. It's not about deer that somehow got caught up in transmission line theory. Hope that clears up any confusion that might possibly arise.
- eldaisfish 2y agoElk is a type of transmission line conductor. Example - https://www.lzcable.com/acsr-elk-conductor/ https://www.lzcable.com/acsr-elk-conductor/ Others include moose and drake.
- cluckindan 2y agoMore info about the various types: https://www.electricaldesks.com/2022/09/Types-of-Conductors-of-Transmission-Lines.html https://www.electricaldesks.com/2022/09/Types-of-Conductors-...
- parsimo2010 2y agoIn the context of this article, it seems clear to me that GP has the right translation. The other figures say "each" in the same position, and it looks like there was one word that didn't get translated from the figure. The fact that this is all on a .nl domain and the author says this is a translation from a Dutch magazine article lends even more weight to the idea that the author wasn't talking about a particular type of transmission line.
- eldaisfish 2y agoi'm pretty confident both of you are correct. I know some Dutch and spotted that as well. I did find it an interesting overlap that in the field of transmission lines (electricity lines specifically) there is literally a conductor size names elk :) My original comment could do with an "also".
- deleted 2y ago[deleted]
- parsimo2010 2y agoA very interesting explanation with history and math combined! I’m not sure if most of HN cares about rf things at this level but I was very happy to see a discussion of transmission lines, and a lot of the discussion of the trades of parameters to improve a Morse code transmission.
- scrlk 2y agoRF is definitely interesting - it's the closest thing to black magic in electrical engineering (all went over my head during my degree...that's why I ended up in power systems :^) ).
- ninalanyon 2y agoBut you still have transmission lines, just at a much lower frequency!
- amelius 2y agoYes, especially since in power transmission the distances are large; if you turn on the power at point A, then point B will not immediately receive the power and this is quite measurable.
- mhh__ 2y agoHe's buried near where I grew up. Must pay him a visit at some point.
- bandrami 2y agoFor years and years I thought the "heavy side" function was 1 on one side of the origin and 0 on the other. I also thought the "pointing" vector pointed in the direction the wave was travelling.
- selecsosi 2y agoNominal Determinism at its finest
- idlewords 2y agoNominative determinism. There's also the pithy Latin phrase nomen omen.
- wholinator2 2y agoOoooh that's so much better. I'm gonna use that from now on. The speed at which you can communicate and the other can understand your statement is very important. I wonder what other common phrases have shorter versions
- IndrekR 2y agoAnd Li-ion batteries are good enough: https://en.wikipedia.org/wiki/John_B._Goodenough https://en.wikipedia.org/wiki/John_B._Goodenough
- dudeinjapan 2y ago[dead]
- dan-robertson 2y agoI always figured the function was named after his haircut
- ychn114 2y ago[dead]
- phreeza 2y agoThis exact theory is also used to model the electrical behavior of neurons in the brain, with some slight differences (no inductances, non-linear resistances), under the name "cable theory" https://en.wikipedia.org/wiki/Cable_theory https://en.wikipedia.org/wiki/Cable_theory I remember one professor mentioning the origin of this theory in undersea cable modeling at some point.
- brunohaid 2y agoTried skimming the page but couldn't find the answer: do we know if the neural connection impedance is perfectly matched? It looks quite organic in shape, with teardrop connections and so on, but curious how nature did that job?
- phreeza 2y agoIt is not always perfectly matched, because the mismatches can actually have a "computational" purpose, but e.g. the typical branching pattern of dendrites is pretty close to being matched . There is a chapter on this in the Dayan and Abbot textbook.
- brunohaid 2y ago<3 awesome - this one https://boulderschool.yale.edu/sites/default/files/files/DayanAbbott.pdf https://boulderschool.yale.edu/sites/default/files/files/Day... ?
- brunohaid 2y agoExcellent post! Controlled impedance took me a long time to wrap my head around when starting PCB design, the moment when it finally clicked was watching this excellent AlphaPhoenix video https://www.youtube.com/watch?v=2AXv49dDQJw& https://www.youtube.com/watch?v=2AXv49dDQJw& asking and practically demonstrating the simple question: When you flip on a switch, to turn on anything, send data, morse something etc, how does the circuit know how much current the load at the other end needs? Spoiler: Given that information can't travel faster than light, the simple answer is: it doesn't. So it just guesses and adjusts, which you don't want as it gives you exactly the ringing etc Heaviside identified. The video is a nice complement, as it perfectly visualizes the issues at play. It's a pretty wild bit of understanding to have, even in simple situations like flipping on a light switch.
- thijson 2y agoI remember reading about the first cable that was laid across the Atlantic. https://en.wikipedia.org/wiki/Transatlantic_telegraph_cable https://en.wikipedia.org/wiki/Transatlantic_telegraph_cable They didn't know much about transmission line theory, and even burned out the cable at one point. Heaviside was only about 8 years old when the first cable was laid down.
- deleted 2y ago[deleted]
- CharlesW 2y agoThat video (and channel, seemingly) is incredible, thank you for posting! I've never seen anything like the visualizations starting at ~10m.
- nyrikki 2y agoThat video is good for the water like wave explanation that is a very useful lens. If you want a more in-depth explanation, particularly how the field is in the dielectric and the wires/traces are simply the wave guide, this long presentation by Rick Hartley will help move to the next level. https://www.youtube.com/live/ySuUZEjARPY https://www.youtube.com/live/ySuUZEjARPY The dramatic shift in behavior above the audio frequency range is where the water wave lens starts to fall down IMHO. I was looking at my brothers memory card from a Cray 1a the other day and that video popped in my head. They had the timing traces snaking through several flat-pack chips legs. No wonder they had to move from parity to Hamming code even with exclusively using differential twisted pairs between modules.
- rezmason 2y agoThere's a fascinating story about ego in science buried here. William Henry Preece was Engineer-In-Chief at the British Post Office in the late 19th Century (basically heading their telegraphy efforts) and controversially stuck to Thomson's model, or the "KR Law" as it was called back then, relying on poor quality experimental results to direct the organization. Oliver Heaviside publicly criticized Preece, who in turn blocked publication of Heaviside's writing to preserve his own reputation (according to Wikipedia). When Preece retired in 1899 and received a knighthood, Heaviside wrote in the preface of Volume II of "Electromagnetic Theory": "It is to be hoped and expected that the late important removals in the British Telegraph Department will lead to much improvement in the quality of official science." Writing by hand on his own copy, Heaviside suggested that the preface (and thus the book's publication) were "held back" so as to "allow W H Preece to make sure of his knighthood". https://outsideecho.com/DGT-BIO_files/PDFs/DGT13.pdf https://outsideecho.com/DGT-BIO_files/PDFs/DGT13.pdf So! On the one hand, we have an esteemed engineer who ran the country's telegraphs and refused to admit he made a mistake, became a knight and faded somewhat from history; on the other hand, we have a self-taught physicist who made massive contributions to our understanding and analysis of electromagnetism, lived in "relative poverty" for fifty years while doing so, didn't shy away from calling out bad science, and he gets the analogue of heaven named after him in the musical "CATS".
- brunohaid 2y agoNot a religious person, but there's something deeply spiritual about Katalin Karikó type characters, who throughout the ages stuck with their curiosities and craft for the craft's sake.
- astrange 2y agoA note on "craft" here is that Heaviside's other thing was inventing a kind of magical math that seems like it shouldn't work (even though it did) and ignoring everyone who complained about it. https://deadreckonings.com/2007/12/07/heavisides-operator-calculus/ https://deadreckonings.com/2007/12/07/heavisides-operator-ca... https://en.wikipedia.org/wiki/Operational_calculus https://en.wikipedia.org/wiki/Operational_calculus
- myth2018 2y agoThank you very much for sharing this. I've been trying to form a mental model of why reflection in transmission lines is a thing and never found a theoretical foundation that satisfied me. I've read a number of publications that just state that as fact, without further explanation. I'll spend some time sketching my own graphs and formulas to fully absorb the fine article. PS: he discusses the impossibility of moving signals faster than light. I'm in fact interested in moving them way slower than they do, since that could make it possible to build very short antennas. I'm surely not the first to think of this. Maybe that's not even possible and that theoretical model could help to demonstrate why (even though it applies to transmission lines while I'm concerned about antennas).
- jrmg 2y agoYes! I’ve dabbled in digital electronics and never managed to form an intuitive understanding on ‘impedance’ in signal wires despite reading quite a few ‘basics’ texts about it. I’d ended up accepting that I wouldn’t really understand its basis without learning a lot more about analog electronics, but this explanation really worked for me.
- basementcat 2y agoFor me, an optics analogy appealed to my intuition. A transmission line is analogous to a periodic crystalline material, perhaps a form of quartz. Impedance is analogous to index of refraction; if two materials of differing index of refraction are juxtaposed, some of the light will reflect back. If the indices of refraction match ("impedance match") then there is no reflection and maximum energy transfer takes place. https://en.m.wikipedia.org/wiki/Refractive_index https://en.m.wikipedia.org/wiki/Refractive_index
- marcosdumay 2y agoYeah, that's easy to work with so it's a great working model. But as an explanation, it leaves a lot to be desired. In fact, I'd say it's easier to explain optical refraction with an electrical model than the other way around.
- myth2018 2y ago
- Jun8 2y agoThis guy was awesome! He innovated ways to solve DEs with Laplace operator for inputs with discontinuities eg, what is now called, the Dirac delta function. Years before the math for generalized functions was developed by mathematicians. When asked about the theory behind the method he happily announced that he doesn’t k ow but that it just worked!
- smallmancontrov 2y ago> Dirac delta function and the Heaviside Step function looks like Heaviside's head lol.
- dmd 2y agohttps://shot.3e.org/ss-20250127_095213.png https://shot.3e.org/ss-20250127_095213.png
- gradschool 2y agoAnother Heaviside biography in addition to the one cited in the article is "Oliver Heaviside: The Life, Work, and Times of an Electrical Genius of the Victorian Age" by Paul J. Nahin. It's profusely illustrated and doesn't omit the math.
- DriftRegion 2y agoI just finished reading this one. It was fantastic. I particularly enjoyed the spicy editorial excerpts from The Electrician ( https://en.m.wikipedia.org/wiki/The_Electrician https://en.m.wikipedia.org/wiki/The_Electrician ).
- vmilner 2y agoPaul Nahins books are so good. See also The Science of Radio And the Mathematical Radio (Similar content but one more focussed at elec eng people and one more at math(s) people)
- B1FF_PSUVM 2y ago> doesn't omit the math. "The best result of mathematics is to be able to do without it", he said, which seems strange but makes sense coming from the man who came up with functional operators. I knew this quotation in my undergrad school days; just now checked the net and there is a source: https://hsm.stackexchange.com/questions/7332/a-peculiar-quote-from-oliver-heaviside https://hsm.stackexchange.com/questions/7332/a-peculiar-quot...
- myself248 2y agoThere's another really good explanation of transmission line theory over here: https://www.ibiblio.org/kuphaldt/electricCircuits/AC/AC_14.html https://www.ibiblio.org/kuphaldt/electricCircuits/AC/AC_14.h... This is the one that finally made impedance "click" in my head. OP's, however, treats the subject of "loading coils", which I remember hearing about in the context of telephone lines but never really understood until just now.
- intalentive 2y ago>One of Heaviside's achievements is that he converted Maxwell's twenty mathematical formulas into a more accessible set of just four, which nowadays are taught at all universities as "Maxwell's equations". Anyone know of an accessible guide to the translation of Maxwell's quaternions to Heaviside's vectors? Was Heaviside's compression of Maxwell's work — lossless?
- BlueTemplar 2y agoI doubt it, as pseudovectors are kind of a mess ? But you can also further compress those 4 equations into just a single one by using slightly more complicated geometry ! http://www.av8n.com/physics/maxwell-ga.htm http://www.av8n.com/physics/maxwell-ga.htm
- black_13 2y ago[dead]
- endoblast 2y agohttps://mathshistory.st-andrews.ac.uk/Biographies/Heaviside/ https://mathshistory.st-andrews.ac.uk/Biographies/Heaviside/ >His neighbours related stories of Heaviside as a strange and embittered hermit who replaced his furniture with 'granite blocks which stood about in the bare rooms like the furnishings of some Neolithic giant. Through those fantastic rooms he wandered, growing dirtier and dirtier, and more and more unkempt - with one exception. His nails were always exquisitely manicured, and painted a glistening cherry pink' Genius confirmed. EDIT: one of the traits of creative genius according to Hans Eysenck is psychoticism which includes an indifference to social norms: https://philipperushton.net/wp-content/uploads/2015/02/Impure-Genius-Psychoticism-Intelligence-and-Creativity-1997-by-John-Philippe-Rushton.pdf https://philipperushton.net/wp-content/uploads/2015/02/Impur...
- antigeox 2y ago[dead]
- Optimal_Persona 2y agoCurious if anyone here is also familiar with loudspeakers built on the acoustic transmission line (TL) principle? It comes and goes in hi-fi circles, I have a bass instrument cabinet produced by the now-defunct Euphonic Audio. It's an interesting TL design featuring a whizzer cone on a 12" speaker. While it isn't the deepest-sounding bass cabinet I've heard, it is very balanced & detailed throughout its range with great projection, and no phase cancellation in the mid/high ranges due to the whizzer/no crossover design. Thanks!
- _yb2s 2y agoI still cannot believe that the Heaviside function is named after it’s creator, rather than simply being a literal description of what it is.