Timeline for Why does the length of an antenna matter when electromagnetic waves propagate perpendicular to the antenna?
Current License: CC BY-SA 4.0
8 events
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| Jul 8 at 16:00 | comment | added | Ján Lalinský | > resonance occurs, which means that the response of the system, the dipole antenna, to the incoming electromagnetic wave, the driver, is maximised. I think it would help a lot if you could add a short explanation for why the "response" (amplitude of voltage on the transmission line) is maximized when a current standing wave is set up (it's clear why this wave is perpendicular to the EM wave received, but why it has to be a standing wave...). In other words, why maximum amplitude of voltage happens for a standing wave oscillation, and not for some other oscillation. | |
| S Jul 7 at 15:11 | history | suggested | Russell McMahon | CC BY-SA 4.0 |
One line added - addresses the complaint "Says what but not why"
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| Jul 7 at 10:35 | review | Suggested edits | |||
| S Jul 7 at 15:11 | |||||
| Jul 5 at 21:59 | comment | added | Farcher | @jawheele Note the direction of the incoming E-field. It is along the conducting rods and that alternating E-field makes the electrons move back and forth along the conductor. If the wavelength of the incoming electromagnetic field is approximately twice that of the length of the dipole as standing wave is set up. | |
| Jul 5 at 21:55 | comment | added | Farcher | @Ken-EnoughaboutMonica Measuring an angle $theta$ from the z-axis in the zx-plane the response of the dipole is approximately proportional to $\cos^2 \theta$. Thus if an electromagnetic wave came from the x-direction the dipole would not pick it up. The dipole acts as a direction finder. | |
| Jul 5 at 19:36 | comment | added | Ken - Enough about Monica | What if the wave isn't aligned with the antenna elements, like it is in the animation? | |
| Jul 5 at 16:47 | comment | added | jawheele | While the animation is nice, this answer simply states that the phenomenon in question exists without giving any indication as to why. It states that the wavelength of the incoming wave as compared to the conductor length is a "key feature", but does not answer OP's question of why this should be the case physically given that these lengths are measured along different dimensions. | |
| Jul 5 at 9:22 | history | answered | Farcher | CC BY-SA 4.0 |