I think I found it.
I can see most enamelled copper wires use polyurethane as enamel product.
4NEC2 has a list of materials but unfortunately polyurethane is not included.
But I found the dielectric constant is 3.5
That value changes with frequency and temperature but I think we can use that
value for the wire antennas.
Regarding the question on how NEC uses this details, and formulas used... to be
honest, I don´t know. Hopefully someone else with more knowledge will replay.
Thank you very much
73, Maximo
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of jimlux
Sent: viernes, 24 de abril de 2020 13:45
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Enamelled copper wire in NEC
On 4/24/20 4:22 AM, Máximo EA1DDO_HK1H wrote:
> Hi,
>
> I use to set my wire antennas as plain copper in when modelling in NEC.
> In the case I would like to get closer to reality and set enamelled copper
> wire in NEC... I don't know what kind of properties to use, for the enamel
> layer.
>
> Please, Any advice here?
>
>
Enameled wire (actually some sort of plastic coating) is pretty thin. I
don't know that it would make much difference in the RF properties at HF
frequencies. Something like AWG 12 "house wire" or the ever popular
lamp (zip) cord has a much thicker coating.
if you have NEC4 which does insulated wires, you can use the IS card to
set the properties of the "insulating sheath". Most plastics have an
epsilon of around 2-3, and very low conductivity (so use something like
1E-6 or 1E-20)
IS 0 tagno segno1 segno2 epsilonr sigma radius
See page 58 in the NEC 4 manual
http://physics.princeton.edu/~mcdonald/examples/NEC_Manuals/NEC4UsersMan.pdf
here's someone discussing it:
http://on5au.be/content/amod/amod50.html
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