Re: S - Y Parameter conversion with Smith Chart

From: John Woodgate (jmw_at_jmwa.demon.contraspam.yuk)
Date: 07/31/04 

Date: Sat, 31 Jul 2004 11:22:59 +0100

I read in sci.electronics.design that Paul Burridge
<pb@notthisbit.osiris1.co.uk> wrote (in <k2flg05dg83q9vhr08gphfq95lfs9p3
f71@4ax.com>) about 'S - Y Parameter conversion with Smith Chart', on
Fri, 30 Jul 2004:
>S-params are typically
>denoted in the form x+/-yj whereas the Y-params are denoted as vector
>and angular co-ordinates, so further mappings and/or translations are
>required following any rotation...

I don't know which way you want to convert, but the conversion from
magnitude and angle to complex Cartesian co-ordinates is:

x = mag*cos(angle), y = mag*sin(angle)

Be careful of the signs of sin and cos if angle is negative. sin is
negative and cos is positive. You can see this if you draw a simple
diagram of x and y axes.

To convert the other way,

mag = sqrt(x^2 + y^2), angle =arctan(y/x).

This isn't difficult mathematics in these days of scientific
calculators, but you do need to be careful about signs, AND check that
the result is credible: if it isn't, you probably made a keying error.

For example, when you calculate angle, then calculate its sin and cos,
to check with the original data. 

-- 
Regards, John Woodgate, OOO - Own Opinions Only. 
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

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