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

"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 21:39:10 -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