Timeline for Does a receiving antenna radiate the power received?
Current License: CC BY-SA 4.0
9 events
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| Aug 26, 2023 at 17:40 | comment | added | hyportnex | @DanielSank I have not met "a" mode matching that is not impedance matching at the same time. Also, holding up a $377\Omega$ is only mode matching if the incoming plane wave's $E$ field is parallel with the resistor, or, better said, with the resistor's internal current flow. As much as I am open and wish to improve on my answer I cannot do so, as I still do not understand your comment, but you are welcome to edit it any time. | |
| May 6, 2022 at 7:35 | comment | added | DanielSank | @hyportnex The impedance of free space is 376 $\Omega$, but if you hold a 376 $\Omega$ resistor up in the air, it will not absorb all of the energy in a travelling electromagnetic wave. The reason is that the wave is distributed over space, it has a mode shape, while the resistor leads have a different shape. So impedance matching and mode matching are different things. | |
| May 5, 2022 at 1:43 | comment | added | hyportnex | @DanielSank I am all for a better answer but do not understand your comment; are you saying that there is impedance matching without the propagating mode of the transmission line connecting the load and the antenna being matched? | |
| May 4, 2022 at 18:51 | comment | added | DanielSank | This answer would be better if it properly distinguished between impedance matching and mode matching. | |
| May 4, 2022 at 18:09 | comment | added | hyportnex | it is not that the load matching changes but rather the energy does not even get to the load because it is "reflected" or "reradiated" back and that is because the incoming wave is not the same kind as the outgoing wave, The incoming is always planar while the outgoing has a very complicated structure especially near the metal, a plane wave cannot recreate that no matter how you match the antenna in a single transmission line mode. In other words you must do much much more to avoid reflections; there is a whole industry to make low visibility antennas (radar or comms); think stealth... | |
| May 4, 2022 at 17:59 | comment | added | niels nielsen | @hyportnex, great answer, +1. -Niels | |
| May 4, 2022 at 17:39 | comment | added | Moulee | thank you for your response. But can you kindly explain the part "that is a matched load for one incident direction maybe mismatched for a different one". I know that based on the direction of incidence the induced voltage might differ but i can't understand on how the load matching can change. could you please explain it further? | |
| May 4, 2022 at 17:20 | history | edited | hyportnex | CC BY-SA 4.0 |
elaborated on the answer
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| May 4, 2022 at 11:23 | history | answered | hyportnex | CC BY-SA 4.0 |