# Near field intensity in terms of antenna thickness

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?

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.

• 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). Commented Jul 18, 2016 at 16:45
• 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. Commented Jul 18, 2016 at 16:48
• @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. Commented Jul 18, 2016 at 17:32
• Thickness can widen bandwidth too. Commented Jul 18, 2016 at 17:45