I landed on this post via a link to your other post on snowblowers from HN.
What you mentioned here--"AM might feel like a clever zero-bandwidth hack: after all, we’re just changing the amplitude of a fixed-frequency sine wave"--is one of the things one of the things that was hard for me to wrap my head around when I first studied radio frequency in high school.
Shouldn't the animations show the half-plates at opposite polarity (or, better, a gradient, as in the drawn animation)? and striped wavefronts showing the polarity of the field? Then receiving antennas graphics could show the effect of either matched or mismatched antennas and impedances and whatnot
The propagation animation represents electric field direction in a manner similar to how they're represented by arrows in the first illustration - i.e., as a region where a charged particle experiences a pull in one direction or another:
Right, would be nice to have the nicely rendered colourful animation better represent the reality, at least with the arc ends at opposite polarity. It is very misleading to show the wavefronts having uniform polarity, especially at ends of the arcs ("lie to children" paradigm?)
I landed on this post via a link to your other post on snowblowers from HN.
What you mentioned here--"AM might feel like a clever zero-bandwidth hack: after all, we’re just changing the amplitude of a fixed-frequency sine wave"--is one of the things one of the things that was hard for me to wrap my head around when I first studied radio frequency in high school.
I had tried asking on [stackexchange](https://electronics.stackexchange.com/questions/438512/why-do-ook-transmissions-have-bandwidth) a while back, and basically got the same answer, but less clearly stated. Moreover, most of the books I read at the time didn't mention this question at all, so I was glad to see you clarify the explanation here.
Nice explanation! I wrote an article on a similar topic, and tells the story of Armstrong.
https://open.substack.com/pub/viksnewsletter/p/how-a-superheterodyne-transceiver?r=222kot&utm_medium=ios
Shouldn't the animations show the half-plates at opposite polarity (or, better, a gradient, as in the drawn animation)? and striped wavefronts showing the polarity of the field? Then receiving antennas graphics could show the effect of either matched or mismatched antennas and impedances and whatnot
The propagation animation represents electric field direction in a manner similar to how they're represented by arrows in the first illustration - i.e., as a region where a charged particle experiences a pull in one direction or another:
https://cdn.britannica.com/96/196-004-767CD0FE/field-lines-charges.jpg
Here's another variant of that antenna animation:
https://upload.wikimedia.org/wikipedia/commons/a/a6/Dipole_xmting_antenna_animation_4_408x318x150ms.gif
Basically, we're just drawing the lines more densely and using hues instead of tiny arrows.
Right, would be nice to have the nicely rendered colourful animation better represent the reality, at least with the arc ends at opposite polarity. It is very misleading to show the wavefronts having uniform polarity, especially at ends of the arcs ("lie to children" paradigm?)