Relationship between Wavelength & Cable Length Formula
Relationship between Wavelength & Cable Length Formula
(OP)
Is there any Wavelength(Lambda) to cable Length formula?
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Relationship between Wavelength & Cable Length Formula
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Relationship between Wavelength & Cable Length FormulaRelationship between Wavelength & Cable Length Formula(OP)
Is there any Wavelength(Lambda) to cable Length formula?
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RE: Relationship between Wavelength & Cable Length Formula
RE: Relationship between Wavelength & Cable Length Formula
I use .667 i.e 2/3 when I don't know. Use it for fault location in cables, usually. The 2/3 makes translation between us and m very easy.
Gunnar Englund
www.gke.org
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Half full - Half empty? I don't mind. It's what in it that counts.
RE: Relationship between Wavelength & Cable Length Formula
RE: Relationship between Wavelength & Cable Length Formula
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: Relationship between Wavelength & Cable Length Formula
In general, for TEM mode with homogenous medium outside the conductor:
u = 1/sqrt(mu*eps)
In a vacuum:u0 = 1/sqrt(mu0*eps0) = speed in vacuum = 3E8m/sec
In medium 1 with properties mu1, eps1:
u1 = 1/sqrt(mu1*eps1)
Considering mu1 = muRel1*mu0 and eps1 = epsRel1*eps0 (where Rel = relative), we can write:
u1 = 1/sqrt(<muRel1*mu0>* <espRel1*eps0>)
u1 = u0/sqrt(muRel1*espRel1)
Typically muRel1 = 1 when discussing cables (only not 1 for devices with cores). Then we have u1 = u0/sqrt(epsRel1) = 3E8 / sqrt(epsRel1)
The velocity factor mentioned above would presumably be 1/sqrt(epsRelative)
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(2B)+(2B)' ?
RE: Relationship between Wavelength & Cable Length Formula
RE: Relationship between Wavelength & Cable Length Formula
I will mention an important assumption of my previous post "homogenous".
Strictly speaking, you could use the equation I gave only for 2 wires immersed in homogenous medium Eps1 in the region between the cables and inside the shield.
When you have non-homogenous medium, the situation is what Waddell (Transmission Line Handbook) calls quasi-TEM. He discusses a parameter EpsEffective which is somewhat of a weighted average of the various permeabilities present (air and insulation.
EpsEffective = Cactual / Cair,
Waddell analytically addresses twisted shielded pair in section 3.3.3. Even with simplifying assumptions it gets messy.
I think the easier approach is google for some thumbrules applicable to your twisted shielded pair cable type.
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(2B)+(2B)' ?
RE: Relationship between Wavelength & Cable Length Formula
should have been
in the region between the conductors and inside the shield
(i.e. the presence of air in addition to insulation in this space within the shield makes it non-homegenous.
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(2B)+(2B)' ?
RE: Relationship between Wavelength & Cable Length Formula
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(2B)+(2B)' ?
RE: Relationship between Wavelength & Cable Length Formula
RE: Relationship between Wavelength & Cable Length Formula
If it's not listed, then contact the manufacturer and ask to speak with the applications engineer.
Or just use 70%.