Wor wrote:
I think "beam" i spolitical name. Antenas with directivity was made by
japanese scientists Yagi and Uda. And after WWII Japan was not very popular
between Americans. So, they name such antennas "beam"

Except Yagi and Uda did their work well before WWII.

The term "beam" is nothing more than slang for a directional device.


--
Jim Pennino

On Sun, 20 Mar 2016 23:02:06 -0700, "Sal M. O'Nella"
wrote:

I'm seeking learned opinions.

Will you settle for uninformed speculation and reverse engineering?

I think we refer to "beam antennas" that way because they behave like lamps
with reflectors, directing a beam of RF like a beam of light. I don’t know
the historical accuracy of my thinking.

Methinks the origin of the term is from the "death ray" weapons that
paralleled early radio development. The Uda-Yagi antenna was invented
in 1926 which included references to "beam-width" which presumably
referred to a narrow "radio beam" as in a death ray. During the same
time, Marconi, Tesla, and others jumped into the "death ray"
competition, claiming to have invented one:
https://en.wikipedia.org/wiki/Death_ray
Even the invention of RADAR was originally inspired by an attempt to
produce a suitable "death ray". In all cases, the proposed "death
ray" was quite directional as it would not do to vaporize the entire
neighborhood. It was often referred to as a "radio beam" or "energy
beam". So, when you announce that you're "turning the beam" in
someone's direction, please take the time to inform them that it's not
a "death ray" that you're aiming.




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

On Wed, 23 Mar 2016 18:29:22 -0700, Jeff Liebermann wrote:

Will you settle for uninformed speculation and reverse engineering?
...
Even the invention of RADAR was originally inspired by an attempt to
produce a suitable "death ray".

Uninformed speculation, indeed.
But, I'm sure once RADAR started being developed and improved,
the military brains of the era thought/sought to weaponize it.

On 24 Mar 2016 14:02:38 GMT, Allodoxaphobia
wrote:

On Wed, 23 Mar 2016 18:29:22 -0700, Jeff Liebermann wrote:

Will you settle for uninformed speculation and reverse engineering?
...
Even the invention of RADAR was originally inspired by an attempt to
produce a suitable "death ray".

Uninformed speculation, indeed.

Yep. Garbage in. Dogma out.

But, I'm sure once RADAR started being developed and improved,
the military brains of the era thought/sought to weaponize it.

Don't be so sure. The original idea in 1939 was to build a death ray
that would cook the pilot of an attacking German airplane. The
calculations were done and it was determined to be impossible. So,
Watson-Watt asked "What can we do to help". Arnold Wilkins recalled
that it was possible to detect an airplane when it created multipath
interference patterns as the airplane flew between the transmitter and
receiver. A field test was arranged, it worked, and the rest it
history.

https://en.wikipedia.org/wiki/History_of_radar
"...had read about a German newspaper article claiming that
the Germans had built a death ray using radio signals,
accompanied by an image of a very large radio antenna."

This video covers the early RADAR development quite nicely.
"The Secret War_2 To See for a Hundred Miles_complete "
https://www.youtube.com/watch?v=ZPwDicTQVBo (50 min)

Nano-drivel: The maximum width of a boat at the water line is called
the vessel "beam". The -3dB width of an antenna pattern is called the
"beam width". Avast ye scurvy dogs connect the dots.

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

"Wor" wrote in message ...

I think "beam" i spolitical name. Antenas with directivity was made by
japanese scientists Yagi and Uda. And after WWII Japan was not very popular
between Americans. So, they name such antennas "beam"

I don't know the correct definition, but my definition is an antenna array
with inline elements.
Those elements can be parasitic or driven. And they can be dipoles, quads,
triangles or whatever.

"Wayne" wrote in message ...



"Wor" wrote in message ...

I think "beam" i spolitical name. Antenas with directivity was made by
japanese scientists Yagi and Uda. And after WWII Japan was not very popular
between Americans. So, they name such antennas "beam"

I don't know the correct definition, but my definition is an antenna array
with inline elements.
Those elements can be parasitic or driven. And they can be dipoles, quads,
triangles or whatever.
================================================== ==
I beginning to get the sense that the definition is sufficiently broad that
the antenna in question has to be described in more detail if the term
"beam" is to be applied.

"Sal"

"Jeff Liebermann" wrote in message
...


Major snippage

Arnold Wilkins recalled
that it was possible to detect an airplane when it created multipath
interference patterns as the airplane flew between the transmitter and
receiver. A field test was arranged, it worked, and the rest it
history.

================================================== =======

I recall an article in an electronics magazine about an aircraft detection
system that worked that way. It was tested in Maryland using the area's TV
station signals.

http://users.ece.gatech.edu/lanterma...ultistatic.pdf

Wikipedia has an article called "Passive Radar."

"Sal"

On Fri, 25 Mar 2016 21:24:45 -0700, "Sal M. O'Nella"
wrote:

I don't know the correct definition, but my definition is an antenna array
with inline elements.
Those elements can be parasitic or driven. And they can be dipoles, quads,
triangles or whatever.

My definition of an antenna is a matching transformer which matched
the output impedance of a transmitter, with that of free space (377
ohms). Convention has it to name the antenna after the designer. In
this case, Shintaro Uda was the student assistant who designed the
antenna, while Hidetsugu Yagi was his university instructor. Uda
published a paper on the design in Japanese, which nobody seemed to
have noticed. A few years later, Yagi translated the paper into
English, which finally got some attention. Its publication resulted
in the antenna being called a Yagi antenna by the American press. Yagi
repeatedly reminded everyone that it was Uda who had designed the
antenna, and deserved the credit. However, the best that could be
done was the Yagi-Uda contraction, which is awkward and backwards.

http://what-is-what.com/what_is/Yagi_Uda_antenna.html
"Despite the fact that Hidetsugu Yagi never took credit for
the antenna's design, it was his name that the American press
used to refer to the concept."

http://www.radiocomms.com.au/content/industry/article/yagi-the-man-behind-the-antenna-647231587
"The technology is all down to Prof Hidetsugu Yagi and his
assistant Shintaro Uda; more to Uda than Yagi, in fact, so
strictly speaking the design should be known as the Uda antenna,
or at least Yagi-Uda."

Incidentally, I have an FM broadcast Yagi-Uda antenna on my roof that
was made by the Yagi-Uda Antenna Company (or something like that).
I'll see if I can find the documentation and post a copy.

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

On Fri, 25 Mar 2016 21:39:10 -0700, "Sal M. O'Nella"
wrote:



"Jeff Liebermann" wrote in message
.. .


Major snippage

Arnold Wilkins recalled
that it was possible to detect an airplane when it created multipath
interference patterns as the airplane flew between the transmitter and
receiver. A field test was arranged, it worked, and the rest it
history.

================================================= ========

I recall an article in an electronics magazine about an aircraft detection
system that worked that way. It was tested in Maryland using the area's TV
station signals.

http://users.ece.gatech.edu/lanterma...ultistatic.pdf

Wikipedia has an article called "Passive Radar."

"Sal"

More correctly, it's CW radar, where the target is illuminated by a
simple carrier, and the interference pattern is detected by a receiver
located somewhere else. While it is possible to use an RF seeking
missile to remove the transmit source, the receiving station(s) are
difficult to find and detect because they emit no RF. The CW
"illumination" transmitter can also be a broadcast TV station, which
is rather politically incorrect to destroy. Similar systems that use
broadcast, cellular, paging, beacons, and repeaters have been built
and tested. I suppose ham operators could have built such a device,
but were probably discouraged by the airlines and military not
offering QSL cards for tracking their flights:
https://en.wikipedia.org/wiki/Continuous-wave_radar
However, please not that it only works with modulation schemes that
have a carrier. SSB, spread spectrum, and some forms of digital data
don't work.

The original RADAR was RDF (radio direction finding). At the time,
most everyone was thinking in terms of some kind of burglar alarm,
where the aircraft would cross a radio "beam" as in the common optical
door annunciator. Other schemes were based on detecting the IR from
hot engines or engine sounds. When the RDF was thrown together, and
combined with the oscilloscope, the designers were amazed that they
could accurately measure range, as well as follow the path of large
artillery shells. So, the "ranging" was added to the acronym.



11PM and I'm still working in the office. I can see it coming...
dinner at midnight (again). What did I do Friday evenings before I
discovered computahs?



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

On 3/26/2016 12:53 AM, Jeff Liebermann wrote:
On Fri, 25 Mar 2016 21:24:45 -0700, "Sal M. O'Nella"
wrote:

I don't know the correct definition, but my definition is an antenna array
with inline elements.
Those elements can be parasitic or driven. And they can be dipoles, quads,
triangles or whatever.

My definition of an antenna is a matching transformer which matched
the output impedance of a transmitter, with that of free space (377
ohms). Convention has it to name the antenna after the designer. In
this case, Shintaro Uda was the student assistant who designed the
antenna, while Hidetsugu Yagi was his university instructor. Uda
published a paper on the design in Japanese, which nobody seemed to
have noticed. A few years later, Yagi translated the paper into
English, which finally got some attention. Its publication resulted
in the antenna being called a Yagi antenna by the American press. Yagi
repeatedly reminded everyone that it was Uda who had designed the
antenna, and deserved the credit. However, the best that could be
done was the Yagi-Uda contraction, which is awkward and backwards.

http://what-is-what.com/what_is/Yagi_Uda_antenna.html
"Despite the fact that Hidetsugu Yagi never took credit for
the antenna's design, it was his name that the American press
used to refer to the concept."

http://www.radiocomms.com.au/content/industry/article/yagi-the-man-behind-the-antenna-647231587
"The technology is all down to Prof Hidetsugu Yagi and his
assistant Shintaro Uda; more to Uda than Yagi, in fact, so
strictly speaking the design should be known as the Uda antenna,
or at least Yagi-Uda."

Incidentally, I have an FM broadcast Yagi-Uda antenna on my roof that
was made by the Yagi-Uda Antenna Company (or something like that).
I'll see if I can find the documentation and post a copy.

Both of these pages were interesting, but hard to read. I don't get why
some pages use a light grey text. I suppose some don't have a problem
reading that, but I do, a *lot*. The other page intentionally added a
shadow to the text, not just the headings or links, making that page
even harder for me to read. I really don't get that either.

I found a few more pages on Yagi-Uda antennas and some derivatives. One
describes how to build a Quagi antenna where the driven element and the
reflector are loops. Seems that works pretty well getting similar
numbers to Yagi type antennas with more directors.

What I really need in an antenna, is something I can add to the ubiquiti
nanostation m900 loco I am using for Internet access. The internal
antenna is only 7.5 dBi. I see a Yagi which is 13 dBi but it seems to
be out of date. The current model is very fancy and is over $200. The
other one is only $33.

--

Rick