RadioBanter - Antenna

Noise to signal ratio

Michael Coslo — Thu, 19 Nov 2009 19:26:16 GMT

Wow, the crazies must be having fun today. Out of 67 new posts, only one
didn't go to my bozo bin.

That guy from Radiobanter must be tearing his hair out......

- 73 de Mike N3LI -

(OT) Inventing a Better Patent System

David Ryeburn — Tue, 17 Nov 2009 06:01:41 GMT

Off topic though this certainly is, I'm posting this because I know that
several people who frequently post in rraa have one or more patents, and
there have over the years been a number of comments here about the sorry
state these days of patents and the patenting process in the USA. Moreover,
with some notable exceptions, postings in this newsgroup often show
intelligence and thoughtfulness on the part of the people making the
postings, more often than in many of the other newsgroups I read.

With that said, I'd enjoy reading comments on the NY Times article
"Inventing a Better Patent System", which you can see at
.
The author makes five specific recommendations for amendments to patent law
which he believes would improve the situation. I'm a (retired) pure
mathematician with no patents whatsoever, and my knowledge of law is nil.
But what he says seems to make sense to me.

If you can illustrate why you agree, or disagree, with points made in the
article by referring to antenna patents (or other patents on related
matters) with which you are familiar, that would be good, and it would make
the issue a little less off-topic. Thanks in advance for reading the article
and making your comments.

David, ex-W8EZE

--
David Ryeburn

To send e-mail, use "ca" instead of "caz".

Mercatino radiantistico italian

ezio — Sun, 15 Nov 2009 20:41:19 GMT

http://www.radioamateur.it/public/mercato/index.php Mercatino
dell'usato per radioamatori interamente realizzato da iz4hyz ( Ezio
Tulli ) vuole essere un servizio per permettere l'incontro di tutti
quegli appassionati di radio (RADIOAMATORI E NON) che vogliono
scambiare materiale radiantistico. Qui puoi vendere, comprare o
scambiare: ricetrasmettitori, antenne direttive, verticali, dipoli
filari, amplificatori lineari, accordatori d'antenne, alimentatori,
componenti elettronici, computer, apparati su 27 Mhz, cavo rg 58, rg8,
rg213, metaldetector, valvole, radio a valvole, circuiti stampati,
saldatori, notebook o altro materiale elettronico che non utilizzi pi�.

Causes of Distrust of NEC and Mininec programs

Art Unwin — Sun, 15 Nov 2009 06:23:05 GMT

Cebic found when comparing different style programs that some behaved
well in certain circumstance where others did not. Yet all antenna
programs
are based on the use of Maxwells equations where all programs should
have the same results, after all Maxwells equations are exact and not
fudged. One of the reasons is that since Maxwells laws are exact
radiators used must be resonant at repeatable points designated as a
period.
Fact is that most users use fractional wavelength designs, usually
a half wavelength, that is not resonant at repeatable points where
the area around the datum line of a sine wave is never equal when
generated around a tank circuit.
The reason for this is "voltage over shoot" which gets smaller
with every cycle but never disappears. Thus when programs are used
based on fractional wavelength radiators the results will never show
100% accountability and in fact efficiencies derived will be in the
order of 92%!
If the radiator is of a wavelength then one is not using a "fudge"
figure
in the calculations and then becomes possible to attain total
accountability with efficiency of 100%. regardles of what type program
is used.
If one is to use exact equations, as are Maxwell equations, then
one must also use measurements that are also exact and repeatable and
that is definitely not fractional wavelengths!
What one gains from this aproach is that any radiator of any shape,
size or elevation can provide figures in the order of 100% as long as
the radiator is a multiple of a wavelength where it is resonant at
exact and repeatable measurements.
If anybody can give pointers that refute the accuracy of the above I
would be very interested in hearing them

re:folded dipole calculator help

Cyclone651 — Sat, 14 Nov 2009 20:56:40 GMT

Your statement:
The fellow I'm disagreeing with say's,
"the reason that the variable in the calculator for the "dipole feed
impedance"
could be if you want to transform the z to something else, such as 50 ohms."
I don't even understand what he means.

My thoughts: My radio output impedance is 50 ohms, for a feed line I use
RG-8 and other 50 ohm impedenance coax.
If I were to use a folded dipole antenna I think I would prefer one that had
a 50 ohm feedpoint.

Nuff said, KD0FGX

Folded Dipole Calculator Help

amdx — Sat, 14 Nov 2009 18:05:21 GMT

Hi All,
I'm having a disagreement about the use of this folded dipole calculator
impedance calculator.
http://www.k7mem.150m.com/Electronic...ed_dipole.html
We are using it to calculate the impedance of folded dipoles to drive a
yagi.
When entering data it asks for "Simple dipole feed impedance (ohms)"
Default is 72 ohms. This assumes a 1/2 wave dipole.
The fellow I'm disagreeing with say's,
"the reason that the variable in the calculator for the "dipole feed
impedance"
could be if you want to transform the z to something else, such as 50 ohms."
I don't even understand what he means.
I can only think of one reason to alter the 72 ohms, that would be if you
use a a different length folded dipole.
I'll readily admit the other fellow knows more about this than me, but
I need more convincing :-)
Can anyone explain this to me.
Thanks, Mike

Matching on the MFJ-1800

amdx — Fri, 13 Nov 2009 13:28:34 GMT

Hi All,
My original thread seems to have died, still wondering how the folded loop
is matched to 50 ohms. (probably isn't? cheap, but works?)
I've added a dimensional drawing and some more pics.
If more info is needed let me know.

Here is a drawing and some more pics.
http://i395.photobucket.com/albums/p...intFileJPG.jpg
http://i395.photobucket.com/albums/p...connection.jpg
http://i395.photobucket.com/albums/p...MFJRuledDE.jpg
http://i395.photobucket.com/albums/p...Jruledcoax.jpg
Hope I covered everything,
Mike

Genius

Bill[_4_] — Wed, 11 Nov 2009 16:41:50 GMT

from http://unwinantennas.com/:

"The Sun is very hot because it is burning. Burning as we know it
produces soot and other by products in abundance that when these
particles collect in the air they become visual to the eye as smoke
even tho the particles themselves are invisible to the eye unless
there is a contrast in light as with particles passing thru a shaft of
light thru a window."

Does the author not understand the difference between fusion and
combustion? Why would anyone pay attention to such an ignoramus when
he writes about antenna theory?

mast position when mounting a beam?

Steve — Wed, 11 Nov 2009 15:06:31 GMT

I'm in the process of putting up a 4 element 6 meter beam.
I'd like it to be balanced but that means I'll be attaching
it to my pole half way between the driven element and
first director. This is a 2" diameter aluminum pole and I'm
concerned that it will interfere with the pattern.

Can anyone say (with some level of confidence) if this is
a problem? Normally, beams seem to be mounted adjacent
to an element. TIA

Steve

Remote progr. antenna rotator AR500 - Manual

D.K.[_2_] — Mon, 09 Nov 2009 13:09:58 GMT

Hi all,
I'm looking for the instructions manual of the "Remote Programmable Antenna
Rotator AR500". I bought one at a local 2nd-hand-ham-market but I can't use
it without the manual.
Has anybody a scan of it ? Or does anybody know a link to download it?
I would be very gratefull if I found any help !
Thanks a lot in advance

Dk
Normandy/France
dominique dot kremp at wanadoo dot fr

Fos sale or swap

Michael[_11_] — Sun, 08 Nov 2009 20:51:39 GMT

I have a 5/8 wave 136 - 230 Mhz, looking for something 2.4 2.5 Ghz.

Multi polarization antenna

Art Unwin — Fri, 06 Nov 2009 01:50:18 GMT

What is the best antenna for use with all circular, horizontal,
vertical and other polarizations without drastic fall of in gain, and
without changes in angular position and feed point via switches e.t.c
at the tower top?

Angry WHY is it spammers and assorted other trash are posted in the WRONG forums??

n9zas — Fri, 06 Nov 2009 00:26:14 GMT

Angry WHY is it spammers and assorted other trash are posted in the WRONG forums??
If EVERYONE would pay attention to what the hell they're posting,then this site would be more enjoyable for everybody here!!! Politics crap does NOT belong in the shortwave forum!!!! Garbage from you tube does NOT belong in the antenna forum!!! Etc,etc!!! Get a clue people,or get lost!!!
Why is it that no one reads what they post... BEFORE they post it??
IS everyone really that stupid? As for SPAMMERS???? ...Death is the only answer for those that have nothing intelligent to add!!!
Wise up already!

SMS?

Cecil Moore[_2_] — Thu, 05 Nov 2009 00:28:15 GMT

Has anyone else noticed that the Prudential commercial
on TV is sending SMS instead of SOS?
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

Entertainment

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