"Owen Duffy" wrote in message
...
"Dr. Barry L. Ornitz" wrote in
:

Of course, it was a distributed delay line. I never measured its
impedance and delay properties accurately, but the cable had a
significant delay that could easily be seen on a 5 MHz bandwidth
scope. Even with an approximate termination, the cable's losses were
quite high.

Do you think this might have been a Distortionless Line?

With the limited bandwidth of the scope, it looked like there was little
distortion. I could see no overshoot or ringing like that seen with
conventional artificial delay lines, but I suspect that
the junky scope was the reason.

In early radars, liquid-filled tubes with acoustic sensors on each end
were used to produce time delays. Typically mercury or water, being
incompressible, were used to fill the tubing. I have seen commercial
delay lines made from quartz rods too. The rods were generally quite
small in diameter but were very long and wound into a spiral. Of course
then there were audio "reverbs" that used springs stretched between
transducers.

Back when I was doing lots of analog computer work simulating automatic
control systems, I used Padé approximations to simulate pure time delay.
Since we are getting rather far away from antennas and transmission
lines, I will give references rather than discuss this here.

--
73, Dr. Barry L. Ornitz WA4VZQ



Padé approximant - Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Pad%C3%A9_approximant

Padé approximation of model with time delays - MATLAB (Control System
Toolbox)
http://www.mathworks.com/access/help.../ref/pade.html

Padé Approximation of Delays
http://www.ee.bilkent.edu.tr/~ee342/Laboratory/pade.pdf

Padé Approximation
http://math.fullerton.edu/mathews/n2...mationMod.html
[Example 9 is especially appropriate]