Re: NEC-List: Wire Radi to printed conductor?

At 9:27 AM -0700 5/10/02, Alan Thomas wrote:
>...the answer is in rho, the bulk resistivity property with respect to
>cross-sectional area and length.
>
>I too am taken aback at the arbitrary approach to such conversions
>and I don't believe it's correct. I don't see pi anywhere.
>
>This is interesting along those lines (no pun intended)- see the PCB
>trace impedance calculator link:
>http://www.polarinstruments.com/menu/home.html

Since you mention "rho, the bulk resistivity property with respect to
cross-sectional area and length," I suspect that you're thinking of
the DC resistance of a conductor. Cross-sectional area is irrelevant
at radio frequency (RF) for practical conductors.

Since this is the NEC-List, I assumed that Wayne Shanks' question was
about the RF inductance and capacitance per unit length of a thin
cylindrical wire or thin flat strip in free space, and that
resistance was negligible.

Calculating PCB trace impedance at RF is beyond NEC. PCBs involve
geometries and combinations of dielectric media and free space that
NEC is unable to model.

Nor is NEC able to calculate the DC resistance of a PCB trace.

-Chuck.

-- 
The NEC-List mailing list <nec-list_at_gweep.ca>
http://www.gweep.ca/mailman/listinfo.cgi/nec-list