On Wed, 02 Aug 2006 14:03:48 GMT, "Frank's" wrote:


"Reg Edwards" wrote in message
...
Frank,
snip
Concerning your previous question about the Smith Chart.
It is a powerful visual aid which gives a better understanding
of what is really happening to the impedances. Exactly what
I got out of graphing the data was really only a confirmation
of the expected spiral toward Zo. Also the "zero-crossing"
which occurs at quarter-wave multiples.
Normalization of the data (Division of each complex datum
by the complex Zo), and linear graphing, will also provide
the same information; including the gradual approach to the
normalized Zo of 1 ohm.

Where the Smith Chart really proves its worth is in the
design of matching networks involving: L, C, R, and
transmission lines. It is hard to imagine how anybody
could do such design without this aid. I am not sure
if anybody actually uses the paper versions these days,
but the software equivalent, combined with programs
such as (Now Agilent's) Eagleware, are pretty much
design lab standards.

In this model all segments are a constant 10 cm in length.
The number of segments will therefore be L(m)/0.1.

Frank

May I insert a few words about the Smith Chart?

During the period between 1958-59 I designed the entire antenna system and
matching harness for the World's first weather satellite, TIROS 1, which was
launched April 1, 1960.

Four transmitters operating simultaneously on separate frequencies fed the
antenna that comprised four crossed monopoles radiating right circular
polarization from two transmitters and left circular polarization on the other
two frequencies.

The point concering the Smith Chart is that the only tools I had for the
development of both the antenna system and the matching harness was the
Hewlett-Packard HP-805 slotted line for impedance measurements, the slide rule
for calculations, and the paper Smith Chart to tell me where I was in the
desert. The resolution available with the Chart was sufficient to make the
system work successfully. Philip Smith was my hero.

Incidentally, the matching harness was fabricated entirely of printed-circuit
stripline, and that was 47 years ago.

Walt, W2DU