E field impedance

George Herold wrote:
> On Monday, October 19, 2020 at 10:37:50 AM UTC-4, George Herold wrote:
>> On Saturday, October 17, 2020 at 3:24:38 PM UTC-4, Tom Del Rosso
>> wrote:
>>> George Herold wrote:
>>>> On Wednesday, October 14, 2020 at 4:58:59 PM UTC-4, Tom Del Rosso
>>>> wrote:
>>>>> As the story goes, the E field starts with high impedance and it
>>>>> goes down until it's equal to the H field impedance in the far
>>>>> field. It's just so counter-intuitive that impedance would go
>>>>> down as you get farther from the source. Is there a somewhat
>>>>> intuitive way to look at that?
>>>
>>>> Like the graph on page 9? here,
>>>> https://www.itu.int/en/ITU-D/Technology/Documents/Events2013/CI_Training_ARB_Tunis_April13/UIT_EMC_fundamentals.pdf
>>>
>>> Yes.
>>>
>>>>> On another matter, I've asked before about the disagreement
>>>>> between some books with diagrams of E and M in phase and some
>>>>> books showing them 90 degrees out of phase. Now I found one
>>>>> source that says they're in phase in the near and 90 degrees in
>>>>> the far.
>>>
>>>> I have a feeling that near field there's a phase difference, with
>>>> leading or lagging determined by the type of source.
>>>> In the far field E and B are in phase... For a long time I had the
>>>> wrong picture of this and imagined that E and B were out of phase
>>>> in the far-field. My hand-wavy understanding of this is that E-M
>>>> waves travelling in empty space experience no time.... (I don't
>>>> understand the 'no time' thing so well either. :^)
>>>
>>> B?  Not H?  I still don't really get the difference but I understand
>>> some things I didn't get a year ago.
>>
>> Yeah, as Phil says for the physics types E and B are fundamental.
>> (E gives the force on a charge and B the torque on a magnetic
>> dipole... as well as other things.)
>>
>> Personally I like Feynman's definition of the H field.
>> The Feynman lectures are free and you might enjoy Vol II chap. 36
>>
>> https://www.feynmanlectures.caltech.edu/II_36.html
>>
>> George H.
>
> I just wanted to add, (echoing Feynman*) that there is a symmetry
> in the electro-static and magneto-static equations when you equate
> the E and H fields. Which is the source of the historic B and H
> confusion. Read the above for more details.
> GH
>
> *and Purcell

That would be enough to grasp, but there's also the fact that one is 
dependent on the core material and the other isn't.