On Wed, 23 Sep 2009 08:26:09 -0700 (PDT), Art Unwin
wrote:


Thank you for confirming the use of eddy currents in the elevation and
projection of scrap materials.
My post states (not confirms) that eddy currents can be used but they
don't work in the manner you suggested. The eddy currents are not
solely responsible for the "elevation and projection" and there is no
"elevate with spin" either. There is certainly no confirmation that
the process is "dependent on the resistivity of the metal elevated" as
you suggest.

My understanding is that the special
purpose machinery industry has now advanced to the ability of sorting
plastic and the like.
Your understanding based upon what? Had you done a modicum of research
you would have a definitive answer about the mechanisms used in
sorting plastics and other non-metallic materials.

A little research beyond glossy brochures filled with marketing-speak
can go a long way in aiding your understanding. You might use a search
engine to locate manufacturers of sorting systems and query the
manufactures for technical details on how their various systems
operate. Your idle speculation based upon incomplete information
serves no purpose.
http://tinyurl.com/clxl9t

On Wed, 23 Sep 2009 12:45:39 -0700 (PDT), Art Unwin
wrote:

I joined the UCSC "Friends of the Library" association in order to
obtain an account. *$35 to $60/year. *

That was about 3 years ago. The price these daze is $75.
http://library.ucsc.edu/giving/friends/friends-of-the-library-membership-benefits
Some other changes. See corrections below.

Now that is interesting!
Visitors can only get on line if the University have them on their
list as being invited
Time period 45 days. I understand that you can't get copies because of
copywrite laws and oversite by the societies so I assume they get
freebees.

Chicago public library seems to have some IEEE Transactions:
http://www.chipublib.org/search/results/?searchType=keyword&terms=IEEE&x=0&y=0
but not Ants and Props. Typing "antenna" into the search box offers
117 books on the subject. That should keep you busy for a while.

There is some pressure on lab schools to place results on the web
since it is public money. The Governor signed a bill a little while
ago on transparency as to where the money goes
But then nobody actually follow all the laws in Chicago and down
state.

There's nothing that prevents you from joining the UCSC or other
university library and ignoring your local problems.

http://giving.ucsc.edu/giving_detail.php?web_id=631

Sigh. The link to joining the Friends of the Library seems to be
broken.

However, there's a catch.
Most of the online IEEE AP-S Transactions are about a year or more
behind. *The various libraries seem to prefer annual subscriptions,
which means most recent issues are often unavailable. *If that
happens, I either pay the price of the download (only if desperate),
or borrow an issue from a friend with a subscription.

Things have changed in the last few years. UCSC now contracts
directly with the IEEE for their online IEEE Transactions. No more
missing recent issues. However, I can't determine if Ants and Props
are available or even if the UCSC Friends of the Library are still
active. I'll inquire shortly as this is much cheaper than joining the
IEEE.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS

On Sep 23, 3:06*pm, Registered User wrote:
On Wed, 23 Sep 2009 08:26:09 -0700 (PDT), Art Unwin

wrote:

Thank you for confirming the use of eddy currents in the elevation and
projection of scrap materials.

My post states (not confirms) that eddy currents can be used but they
don't work in the manner you suggested. The eddy currents are not
solely responsible for the "elevation and projection" and there is no
"elevate with spin" either. There is certainly no confirmation that
the process is "dependent on the resistivity of the metal elevated" as
you suggest.

My understanding is that the special
purpose machinery industry has now advanced to the ability of sorting
plastic and the like.

Your understanding based upon what? Had you done a modicum of research
you would have a definitive answer about the mechanisms used in
sorting plastics and other non-metallic materials.

A little research beyond glossy brochures filled with marketing-speak
can go a long way in aiding your understanding. You might use a search
engine to locate manufacturers of sorting systems and query the
manufactures for technical details on how their various systems
operate. Your idle speculation based upon incomplete information
serves no purpose.http://tinyurl.com/clxl9t

Fine.
Your correct and I am wrong.That should make you feel good
It matters little to me that my thoughts are different than yours so
that is the end of it.
Have a happy day

Richard Fry wrote:

No matter how short a dipole antenna is in wavelengths, current is
always zero at the ends of each arm of that dipole.

The current distribution on a thin, wire dipole takes the form of a
sine wave. If the antenna is short, as in this case, then the only
part of the sine that can exist is nearly linear. Hence the
~triangular shape for the total current on the dipole.

Confirm this for yourself using Figure 2-2(b) on page 2-4 of the
following link.

http://books.google.com/books?id=xTS... tenna&f=false

RF

You can also do it in a few seconds using the free EZNEC demo program.
Open the Dipole1.ez example and the View Antenna display. Click the
Currents (or FF Plot) button and see the current distribution in the
View Antenna display. Then change the frequency to 3 MHz to make the
dipole 0.05 wavelength long and click Currents or FF Plot again and see
the altered current distribution. You can see the shape better by using
the Current zoom control at the left of the View Antenna display.

As an additional educational exercise, compare the gains and patterns of
the lossless 0.5 and 0.05 wavelength antennas.

Roy Lewallen, W7EL

"Art Unwin" wrote in message
...
So you are back David ! have you built that four poster antenna yet,
of steel I presume, for the top band?

only 2 elements for top band, 4 for 80m out of rohn tower, and 4 for 40m out
of steel pipe towers... and they all work great without any magical
levitating diamagnetic solar neutrinos!

Haven't heard you mention anymore about
that book you were writing on antennas. I assume you do not have a
chapter about equilibrium as yet.

i never said i was writing a book on antennas. it has some antennas in it,
but its not about antennas.

"Szczepan Bialek" wrote in message
...

I have onmy shelf the Fluid dynamics by Dr Ludwig Prandtl. Prandtl is a
big name.
S*
maybe in fluid dynamics, but not in electromagnetics.

On Sep 17, 11:59*pm, Szczepan Bia³ek wrote:
*"K7ITM" ...
....
reasonably simple terms. *One of the best I know is Joseph Boyer's
pair of articles from May and June, I think it was, 1978 "Ham Radio"
magazine: *"The Antenna-Transmission Line Analog." *It's a non-
mathematical work; it will leave you with answers with not a lot to
back them up, but they do match what we observe, as far as I
understand it. *I have these as a PDF, along with a fairly important
section from a book referenced by the articles.

You send me to library. ...

No, actually I told you that I have the article plus one of the
important references as a PDF [file]. It's certainly not worth my
effort or the net bandwidth for me to try to repeat what that article
has already done a good job with. Also, I gather from some of the
postings in this thread that you're more interested in arguing and
being negative than in reading such an article.

Cheers,
Tom

On Sep 23, 1:12*pm, Szczepan Bia³ek wrote:
The simplest dipole is a transmissing line (the two wires).

Not so.

A transmission line with balanced currents is not a dipole, and does
not / cannot produce the radiated fields of a dipole.

Kindly confirm such by your study and accurate comprehension of
engineering texts on this subject.

RF

On Sep 23, 1:00*pm, Szczepan Bia³ek wrote:
Now you have my description. Which one do you prefer?

The one that can be proven by scientific principles, and shown by
practical performance.

RF

Richard Clark wrote:
On Wed, 23 Sep 2009 07:16:49 -0500, tom wrote:

Cecil Moore wrote:
tom wrote:
Note that none of these are particularly close to resonance at the
design frequency.
Yagis do have a resonant frequency but that frequency
is not at the design frequency. At the resonant frequency,
the forward gain and F/B ratio are not optimum. At the
optimum forward gain frequency and/or F/B ratio frequency,
the Yagi, sans matching network, is not resonant.

That's about as useful as saying you do not obtain the maximum miles
per gallon in your car when the ashtray is half full or when the
carpets are at their optimal brushed out nap.

73's
Richard Clark, KB7QHC

Nice attribution to me Richard, but Cecil wrote it.

And it makes a lot more sense than your statement, although he could
have worded it better.

tom
K0TAR