Brilliant I did an RAF course on ground wireless as a boy entrant in the 50's of course we had no video at the time. Photon energy transmission is the same mechanism and this illustrates that principle. The wonders of resonance from the breaking wine glass to a CO2 molecule?
on dipole electric and magnetic standing waves has 90 degrees phase difference. but propagating electric and magnetic waves has no phase difference. why and how?
as i understand shortly. propagating h (magnetic) wave produced by dipole electric wave, so they are in phase. since changing e fields produce magnetic field at the same phase. from this video maybe we can say whenever e and h waves at 90 phase difference, they produce propagating em waves at the same phase.
Do I need to be licensed to translate to Spanish? I noticed that there is no text in the video, which made me think it would be an excellent pedagogical tool.
1:04 - it should be noted that this visual representation is not a sign wave form but momentary pulses as it does not fade in and out. Indeed, radiating from one point wouldn't have the dynamic of traveling along a radiating element, so that doesn't mean it is necessarily incorrect, just not representative.
1:43 While electrons do move it is not the electrons themselves that are moving this distance but rather their electrical field, similar you could say to how a wave travels across water though the actual specific molecules of water aren't traveling the full length of the wave's propagation.
I am not as impressed by this film as most other viewers seem to be. There are two major shortcomings: First, the question of why the "pulsating" electric and magnetic near-fields around the dipole travel out into space is not addressed. Instead, at 5:10 they weirdly move the "field of view" away from the antenna and just claim that there is indeed propagation with E always being perpendicular to H (which, of course, is true, but for somebody without prior understanding of electrodynamics, is not evident why that should be at all) Second, when they "explain" reflection at surfaces, they simply state that the E-vector is instantaneously reversed, while the H-vector is not (8:06). For someone who is not an expert (and therefore the target audience of this movie) this seems completely arbitrary, and no explanation is given as to why. So yes, the film is good in parts, but unsatisfactory in others...
In this diagram animation BOTH the VOLTAGE and CURRENT (fields) are drawn as strongest in the middle of the antenna. As far as I know one of them should be stronger at the tips of the antenna and the other weak at the tips but strong at the feed points.
I think it depends on the wavelength relation of the antenna and where the feed point is. I recently saw a video that illustrated your exact point, but I'm trying to remember what was said. I found it by accident. I feel like it had to do with an end fed antenna, made at a fractional wavelength and showing why a center fed dipole is so desirable, but an end fed (while more practical in building and mounting) is a compromise electromagnetically. I think it was regarding building a 160m antenna. The guy was explaining the trade offs and difficulties in building such a long antenna for that band.
