How 'bout this...'

"Jerry Martes" wrote in message
news
"Richard Clark" wrote in message
...
On Mon, 10 May 2004 06:22:29 GMT, "Jerry Martes"
wrote:
making a slotted line.

Hi Jerry,
[...] As for why a slab style over a cylinder style. That for me is
taken
on faith that greater minds, in the person of HP Metrologists, figured
that one out a long time ago. ...
73's
Richard Clark, KB7QHC

Richard

I used to think the HP slab configuration was choosen so as to put the
probe in a place of minimum fiels within the line.
Jerry


Gents.
What you are calling "slab line" is more properly called "Stripline".
It is a very well defined type of transmission line...that is, it has exact
equations (unlike the one-sided Micro-strip). I suspect that Jerry's
conclusion is right-on. At least theoretically, there is zero field along a
line through the center conductor, parallel to the ground planes. So it
appears that you would indeed disturb things the least...as long as your
'probe' exited parallel to the ground planes.
Ignore everything but the lower right figure on page 3 of the stripline E
field:
http://www.altera.com/literature/wp/lvdsboardwp.pdf

It is all sort of 'sucked' into the ground planes...
The best pix I could find... I think as long as the probe has a small cross
section when viewed from the line you will disturb the field the least.
Seems to me in the old days, the probe consisted of a 1N21 diode...
--
Steve N, K,9;d, c. i My email has no u's.