On 8 Dec 2006 05:05:33 -0800, "4nec2" wrote:

....
Below, a random short inverted-V for 80, delivering a Z-in of around
16.3 - j 826 ohms
....

Just working through a solution using a single o/c stub match using
Cebik's calculator for Wireman 551 ladder line, Zo=400, vfr=0.902.

Length of series section is 13.029m, length of stub is 19.163m. This
is correct for lossless line.

Now lets look at the Y looking into the series section using the line
loss calculator at http://www.vk1od.net/tl/tllc.php , it is
0.030478+j0.067004. Now shunt that with the Y looking into the o/c
stub of 0.017872-j0.076378. Add them for a Y of 4.835E-002+j0.143382,
or Z of 2.11171146485231-j6.26228362468365 or VSWR of 22:1.

What went wrong?

In some cases, assuming lossless lines is not valid, and you don't
really know if you don't calculate the effects of the loss.

Owen

PS: the correct solution will be a slightly shorter series section and
a slightly longer stub. It is still not a good (practical) solution.
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