Loading coils: was Dish reflector now: Delay Lines
 

"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]

Loading coils: was Dish reflector now: Delay Lines
 

"Dr. Barry L. Ornitz" wrote in news:2BoIl.67540
:

Since we are getting rather far away from antennas and transmission
lines, I will give references rather than discuss this here.

Well, we all like Distortionless Lines, almost all ham discussion and
indeed much if not most textbook discussion is about one special case of a
Distortionless Line, the Lossless Line.

Nevertheless, we apply one property of Distortionless Lines to real lines,
the property that Zo=Ro+j0, and that Zo is independent of frequency.

But, a real Distortionless Line (real excludes Lossless) doesn't have much
application for us.

Though I haven't had my hands on a Distortionless Line, it occurs to me
that increasing L/m is a means of diminishing the effect of changing R/m,
making G/m higher is another means of making Zo real, and if the materials
make R/m(f) track G/m(f) closely ... then the problem is mostly solved.

Owen

Loading coils: was Dish reflector
 

On Apr 24, 2:08*pm, "Dave" wrote:
"Art Unwin" wrote in message

...
On Apr 24, 11:25 am, Art Unwin wrote:



On Apr 24, 10:47 am, "Dave" wrote:

"Art Unwin" wrote in message

....
On Apr 24, 7:48 am, Art Unwin wrote:

Please allow me to correct myself on the above

you never did answer my question, but thats ok, you never have before
either... now you try parsing the language and think that provides
insight... just write the equation, what is equilibrium in your mind? i
know this is tough, you are so far out of balance anyway, but try to
amuse
me a bit and write a concise definition of 'equilibrium'.

I will be happy to David
It is balance as referred to by the mathematical equal (=) term where

so any equation with an equals sign is in equilibrium?? *that applies to
everything then, since all equations contain an equals sign they are all in
equilibrium by definition. *my i'm glad you explained that art, i might have
gone through life never knowing that by taking e=ir and rewriting it as
e-ir=0 i have put ohms law in equilibrium and then all is well with the
universe! *so the conversion of mass to energy in the famous equation e=mc^2
is really in equilibrium as e-mc^2=0, so no mass is converted to energy or
vice versa! *wow, what a revelation! *thanks again art!

Well not exactly. The innards of the arbitary boundary must be in a
state of equilibrium
thus when making the arbitrary field a dynamic field by adding time or
such things as radiators the innards must stay in equilibrium. Thus if
radiators are added they also must be in equilibrium which requires
all to be approximately one WL or the equivalent of one or more
periods of the frequency in use. Thus the majoritory of added
radiators may be the one of choice in terms of feed point

Loading coils: was Dish reflector
 

"Art Unwin" wrote in message
...
On Apr 24, 2:08 pm, "Dave" wrote:

radiators are added they also must be in equilibrium which requires
all to be approximately one WL or the equivalent of one or more
periods of the frequency in use. Thus the majoritory of added
radiators may be the one of choice in terms of feed point

ok, if a one wl radiator is in equilibrium, give me the equation describing
the current and radiation pattern from that radiator in free space.

Loading coils: was Dish reflector
 

On Apr 24, 5:37*pm, "Dave" wrote:
"Art Unwin" wrote in message

...
On Apr 24, 2:08 pm, "Dave" wrote:

radiators are added they also must be in equilibrium which requires
all to be approximately one WL or the equivalent of one or more
periods of the frequency in use. Thus the majoritory of added
radiators may be the one of choice in terms of feed point

ok, if a one wl radiator is in equilibrium, give me the equation describing
the current and radiation pattern from that radiator in free space.

David you are fishing for info for your next phase of attack. Soon I
will get right on it and work thru day and night and all weekends per
your request of me so please do not arrest me if I do not fullfill all
of your expectations of me. I have asked my wife to delay her birthday
because obviously your demands of me with respect to antennas or
equilibrium comes first. I would remind you that I did supply
dimensions of a tipped radiator in equilibrium some time ago on this
newsgroup but you showed zero interest. What has changed?
Your devoted servant
Art

Loading coils: was Dish reflector
 

Art Unwin wrote:
I would remind you that I did supply
dimensions of a tipped radiator in equilibrium some time ago on this
newsgroup but you showed zero interest. What has changed?
Your devoted servant
Art

X (sub) L = X (sub) C

Is this what you mean by "equilibrium"?

Loading coils: was Dish reflector
 

"Art Unwin" wrote in message
...
On Apr 24, 5:37 pm, "Dave" wrote:
I would remind you that I did supply
dimensions of a tipped radiator in equilibrium some time ago on this
newsgroup but you showed zero interest. What has changed?
Your devoted servant

tipping a radiator is an obvious exploit of changes in pattern by
unbalancing the ground current. it gives some gain in one direction at the
expense of other directions. it is not all that useful unless you want a
tipsy looking antenna and are covering a fixed direction... unless you made
an array of tipsy verticals for vhf and rotated them... that might be fun.
besides i had enough bent elements from the winter ice, they didn't improve
the yagi performance. so i've had enough of that. but 'equilibrium' as
defined by art is a magic jewel to be examined.

i do take exception with 'dave' though, the equation should be Xl=-Xc or
Xl+Xc=0 to put it in art's form.

Loading coils: was Dish reflector
 

On Apr 24, 6:48*pm, dave wrote:
Art Unwin wrote:
*I would remind you that I did supply
dimensions of a tipped radiator in equilibrium some time ago on this
newsgroup but you showed zero interest. What has changed?
Your devoted servant
Art

X (sub) L = X (sub) C

Is this what you mean by "equilibrium"?

There is something going on
I am outa here.
Why not just review my patent request to get the info

Loading coils: was Dish reflector
 

Art Unwin wrote:
I am outa here.

First accurate thing he has said in a while.

Hang on, possibly I am confused. Maybe it was precise. Yup, I am
resolute now.

tom
K0TAR

Loading coils: was Dish reflector now: Delay Lines
 

"Owen Duffy" wrote in message
...
Well, we all like Distortionless Lines, almost all ham discussion
and indeed much if not most textbook discussion is about one
special case of a Distortionless Line, the Lossless Line.

Nevertheless, we apply one property of Distortionless Lines to
real lines, the property that Zo=Ro+j0, and that Zo is independent
of frequency.

Or, in other words, the Heaviside Condition is met.

C/G = L/R

This is met in lossless lines with R and G being zero, and the
characteristic
impedance being real.
_____________________ _____
Zo = v((R + j?L)/(G + j?C)) = v(L/C)

But, a real Distortionless Line (real excludes Lossless) doesn't
have much application for us.

Consider that with real inductors and capacitors, the permeability,
µ, and the permittivity, e, are themselves often complex.

µ = µ' + jµ" and e = e' + je"

Of the two, I am most familiar with dielectric properties of
polymers as a function of frequency. With plastics like
polyethylene and polytetrafluoroethylene, e' (the real part) remains
fairly constant from low frequencies well into the microwave region,
and e" (the imaginary part) is quite low. Plastics like
polyvinylchloride, on the other hand, show an increasing e" with
frequency due to rotational hindrances of strong dipoles in the
polymer.

Similar frequency dependencies are seen at optical frequencies,
where the refractive index is a function of wavelength. Chromatic
aberration, the failure of a lens to focus all colors to the same
point, is caused by this change of refractive index with
wavelength. In general, the refractive index of a material
increases with increasing frequency. In the infrared and visible
portions of the spectra, we see large changes in permittivity
because of vibrational resonances in the polymer groups.

Though I haven't had my hands on a Distortionless Line, it occurs
to me that increasing L/m is a means of diminishing the effect of
changing R/m, making G/m higher is another means of making Zo
real, and if the materials make R/m(f) track G/m(f) closely ...
then the problem is mostly solved.

With typical commercial coaxial cables, the ratio of shunt
conductance to shunt capacitance is generally much lower than the
ratio of series resistance to series inductance (all per unit
length). This makes the characteristic impedance complex, and the
cable causes distortion.

In the weird cable I described earlier, the resistance of the wire
would increase linearly with the number of turns per unit length but
the inductance would increase as the square of the turns per unit
length. So there would be merit here. Increasing the shunt
conductance will also help — at the expense of making the cable
extremely lossy.

While we have been talking about conventional electrical
transmission lines, we can also analyze nerves as a transmission
line. A nerve is essentially an electrical transmission line with
chemical transducers on each end. When a receptor synapse detects
a neurotransmitter, like serotonin or norepinephrin, it sends an
electrical signal down the neuron. The neuron is the transmission
line. It is essentially an ionic conductor covered with a fatty
substance known as myelin. The result is a distributed resistance-
capacitance line. In diabetics, the myelin sheath is partially
destroyed and replaced with sorbitol, a sugar alcohol. In addition
to being more conductive than myelin, sorbitol has a far higher
dielectric constant. Viewing the neuron as a distributed RC line,
we have both added shunt conductance and increased the capacitance.
It is no wonder that nerve conduction velocity and amplitude both
decrease resulting in such things as peripheral neuropathy, usually
associated with diabetics.

--
73, Dr. Barry L. Ornitz WA4VZQ