I've been thinking about the skin effect and that got me thinking: When high frequency current goes through a superconductor, does it still radiate off like it would with copper?
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1\$\begingroup\$ What have you found so far in your search? \$\endgroup\$– pipeCommented Dec 24, 2017 at 17:30
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1\$\begingroup\$ Well, what causes radiation? \$\endgroup\$– PlasmaHHCommented Dec 24, 2017 at 17:39
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\$\begingroup\$ Yes. There are radiations due to the AC current in the conductor, and thermal radiations due to the resistance of the conductor, which are lower for supraconductors than copper. \$\endgroup\$– GrabulCommented Dec 24, 2017 at 17:49
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2\$\begingroup\$ Superconductors have zero resistance. That's what makes them superconductors. \$\endgroup\$– Ian BlandCommented Dec 24, 2017 at 17:57
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7\$\begingroup\$ If the current is not DC, then I think some radiation would come off of the conductor due to a time varying magnetic field. In other words, a superconducting antenna would still be an antenna. \$\endgroup\$– user57037Commented Dec 24, 2017 at 18:16
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Yes. Regardless of the resistance in a conductor, when a time varying current flows, it gives rise to a time varying magnetic field outside the conductor. When conditions are right, that time-varying magnetic field will give rise to a transverse electromagnetic wave (TEM).
In other words, an antenna constructed from super-conducting elements would still function as an antenna. The fact that the series resistance is zero does not prevent the antenna from functioning.
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\$\begingroup\$ How much would radiate off compared to copper? \$\endgroup\$– MaxCommented Dec 25, 2017 at 19:29
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1\$\begingroup\$ If the current is the same, I think the radiation would be the same. \$\endgroup\$ Commented Dec 25, 2017 at 19:50
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\$\begingroup\$ It wouldn't be less due to lower resistance? \$\endgroup\$– MaxCommented Dec 26, 2017 at 2:38
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1\$\begingroup\$ Post a new question. If skin effect still occurs, that would imply a non-uniform current density throughout the conductor cross-section. Superconductivity applies only up to some maximum current density. Above that, the super-condcutor has non-zero resistance. If skin effect concentrates the current density into the outer surface of the conductor, it may reach that limit at a lower total current. \$\endgroup\$ Commented Dec 27, 2017 at 4:14
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1\$\begingroup\$ It should maybe be mentioned that the radiation resistance effect means a superconducting antenna would present a nonzero resistance to the rest of the circuit, even while still superconducting, because some of the energy of the current in the antenna would be transferred to the generated EM waves. \$\endgroup\$– zwolCommented Jun 6, 2019 at 15:42