3 ms·
Unless I'm missing something, I don't think reciprocity helps you much here. There is a contained radiation field when the antenna is excited; there are no fie
by jpmattia 5y ago
Unless I'm missing something, I don't think reciprocity helps you much here. There is a contained radiation field when the antenna is excited; there are no fields far away. Now when you start with no fields far away, it doesn't tell you much about the excitation near the antenna.
You can envision some radiation pattern from far away antennas which have overlap with the near-field modes. As a consequence, some amount of energy will be received by this antenna. Naturally it depends on how well the near-field mode is excited as to how much coupling occurs.
- jbay808 5y agoWhat I mean by reciprocity is, if distant far-field antenna B can transfer energy to our contained-field antenna A, then shouldn't our contained-field antenna A also be able to transfer energy to the far-field antenna B? Wouldn't that be inconsistent with A not having a far-field emission? If A doesn't produce any field at B, then it doesn't seem possible that the field B produces at A could be absorbed by A. Thermodynamics should guarantee this, otherwise you could use it (in a roundabout way) to violate the second law.