I've been told that the near field created by a thin wire "antenna" goes to infinity in a neighborhood of the antenna as the wire gets thinner and thinner. However, I'm not able to find any tables or graphs of this fact. Could anyone provide a reference where I could check some values?
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In an EM radiating antenna a proper EM field does not form until beyond the near field: -
On the diagram above proper coherent EM waves are in the far-field. Of course if you could build an antenna that operated at DC the near field would extend to infinity: -
But I doubt that the thickness of the wire has anything to do with it. You have to match the E and H fields to the impedance of free space (377 ohms) to make an EM antenna an effective radiator: -
E and H fields in the near field are neither of the correct ratio nor of the correct phase angle with respect to each other. They decay individually as \$\dfrac{1}{d^3}\$. In the far field they individually decay as \$\dfrac{1}{d}\$
On this basis alone your question contradicts itself because you cannot be referring to a real EM antenna.
answered Jul 18, 2016 at 16:16
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\$\begingroup\$ I know the near field is not real propagation, and that's why I wrote "antenna" and not antenna. Think of it as a wire alone. In this case, the thickness of the wire does have an effect on the intensity of the field (which doesn't propagate, but I don't care). \$\endgroup\$– nablaCommented Jul 18, 2016 at 16:45
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\$\begingroup\$ I don't see the point of your comment. Near field propagation can still be real energy transfer but not as effective as a fully fledged EM wave. Without the ability to propagate in the far field such a device is not an EM antenna in my book. \$\endgroup\$– Andy akaCommented Jul 18, 2016 at 16:48
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\$\begingroup\$ @gerd Any conductor is an antenna or "antenna". The thickness mostly alters some the resistance of the antenna, which is a pure loss, at no matter far or near field. \$\endgroup\$ Commented Jul 18, 2016 at 17:32
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\$\begingroup\$ Thickness can widen bandwidth too. \$\endgroup\$– Andy akaCommented Jul 18, 2016 at 17:45