[NLRS] Help with math

[Scott]

Actually, I found a site that does the calculation for you!  I 
calculated that a 0.1" wide line should be 48.75 Ohm, which sounds close 
enough for me!  Does that sound like a reasonable value???

Now, does anybody have a good way of making a mask for photoresist 
etching of the board?

The website is at http://www.microwaves101.com/encyclopedia/calmstrip.cfm

Scott
N0EDV

Scott wrote:

> 
> 
> I'm having some trouble with my math (I am NOT a math major!)...
> 
> I am trying to find a microstrip width for DEMI circuit board (they call 
> it Duroid 5880 equivalent).
> 
> If so, it should have a dielectric constant (Er) of about 2.20.
> 
> Looking in my (VERY BRITISH) VHF/UHF Manual, here is the formula for 
> width of a microstripline...
> 
> Log(subscript 10)W= 0.8736 + log(subscript10)t -0.004992 x Z X (Sqroot 
> Er) + 1.14
> 
> W=width (mm)
> t= thickness (mm)
> Z=Impedance
> 
> So Er=2.20
> Z=50 Ohm
> t=0.787 mm (0.031")
> 
> What is W (in mm)??
> 
> Or, has anyone built 50 Ohm line on DEMI 0.031" circuit board and if so, 
> how wide were the strips????
> 

-- 
Scott
http://corbenflyer.tripod.com/
Building RV-4
Gotta Fly or Gonna Die