In article , I wrote:
A word: synthetic aperture.

Drone array, anyone?

[...]

Or just calculate directly. I think the angular
resolution of an array or a telescope in radians is
something like

0.22 * wavelength / aperture .


Oops. That's 1.22 .

Still, I don't think it's too bad considering how
long ago I learned about synthetic aperture
arrays in 2nd year physics.

George

On 14 Jul 2015 03:00:32 -0400, (George
Cornelius) wrote:

In article , Jeff Liebermann writes:
let me "see" RF. It certainly would make troubleshooting RF devices
much easier. Essentially, it would be a human eye analog implimented
with RF components. According to theory, if it works for light, it
should also work for RF. At the time, I was working at about 1GHz.
Light is about 400 THz. So, all I need is an eyeball that's 400,000
times larger than the human eye. I'll give myself a -1 for the idea.

A word: synthetic aperture. Remember the dish arrays in
the Jodie Foster movie Contact? You still need the same
scale factor - many times the wavelength - but most of a
dish array can be air.

So with the eyeball analogy, I would first reduce to the
size of the pupil - the aperture - and that is perhaps
5 mm. Times 400K gives 2000m for the same theoretical
resolution. Of course, for a 2D image you would need
an array of antennas spread over a disk of that radius.

Or just calculate directly. I think the angular
resolution of an array or a telescope in radians is
something like

0.22 * wavelength / aperture .

Multiply by about 60 to get degrees.

So for 1 Ghz (.3m) it's 0.22 * .3m / 2000m, or
33 x 10^-6 radians. About 7 seconds of arc.

George

Thanks and interesting. I discarded synthetic aperture imaging
because I assumed that either the sensor array or the object being
imaged had to be moving roughly perpendicular to each other. That
seems to be the case with SAR (synthetic aperture radar). I'll read
some more (later) as I have no experience with the technology.

--
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 7/13/2015 10:59 AM, Jeff Liebermann wrote:
On Mon, 13 Jul 2015 13:45:43 +0200, "bilou" wrote:

"Jeff Liebermann" wrote in message
...

Yep, antennas radiate photons.
+1
There is not any proof that RF behaves differently than light.
Things are already quite complicated without it :-)

One of my not so great ideas was to devise a contraption that would
let me "see" RF. It certainly would make troubleshooting RF devices
much easier. Essentially, it would be a human eye analog implimented
with RF components. According to theory, if it works for light, it
should also work for RF. At the time, I was working at about 1GHz.
Light is about 400 THz. So, all I need is an eyeball that's 400,000
times larger than the human eye. I'll give myself a -1 for the idea.

I think they have that. They are called radio telescope arrays.

--

Rick

"Jeff Liebermann" wrote in message
...
One of my not so great ideas was to devise a contraption that would
let me "see" RF. It certainly would make troubleshooting RF devices
much easier. Essentially, it would be a human eye analog implimented
with RF components. According to theory, if it works for light, it
should also work for RF. At the time, I was working at about 1GHz.
Light is about 400 THz. So, all I need is an eyeball that's 400,000
times larger than the human eye. I'll give myself a -1 for the idea.
Hi
As usual others had the same idea .Look here :
https://youtu.be/DovunOxlY1k?t=81

On Fri, 21 Aug 2015 00:07:43 +0200, "bilou" wrote:

"Jeff Liebermann" wrote in message
.. .
One of my not so great ideas was to devise a contraption that would
let me "see" RF. It certainly would make troubleshooting RF devices
much easier. Essentially, it would be a human eye analog implimented
with RF components. According to theory, if it works for light, it
should also work for RF. At the time, I was working at about 1GHz.
Light is about 400 THz. So, all I need is an eyeball that's 400,000
times larger than the human eye. I'll give myself a -1 for the idea.

As usual others had the same idea .Look here :
https://youtu.be/DovunOxlY1k?t=81

Nope. The AT&T wave demo is a mechanical analogy of wave phenomenon.
That's not what I'm looking for. What I want is the ability to look
at a radio, power amp, amplifier, etc and actually see the RF leaking
from the circuit, or just standing there in the form of standing
waves. Like light, I would not expect to see conducted RF, only
radiated RF. However, I think there will be enough of both to make
the effort worthwhile.

Incidentally, if you're into surfing the waves, this should keep you
entertained for days:
http://www.falstad.com/mathphysics.html (Java required)
(Note: Seems to work better when on controlled substances).

--
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 Mon, 13 Jul 2015 13:45:43 +0200, "bilou" wrote:

There is not any proof that RF behaves differently than light.
Things are already quite complicated without it :-)

Sure there is. After half a century of exposure to RF, my hair is
falling out, my hand is shaking, and my bank account depleted. Other
people, who were only exposed to light, have not had these things
happen. I can only conclude that RF is somehow dangerous and
different from light.


--
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 7/14/15 4:13 PM, Jeff Liebermann wrote:
On Mon, 13 Jul 2015 13:45:43 +0200, "bilou" wrote:

There is not any proof that RF behaves differently than light.
Things are already quite complicated without it :-)

Sure there is. After half a century of exposure to RF, my hair is
falling out, my hand is shaking, and my bank account depleted. Other
people, who were only exposed to light, have not had these things
happen. I can only conclude that RF is somehow dangerous and
different from light.



That's gotta be it, by the infallible principle of Post Hoc Ergo Propter
Hoc.

On Fri, 17 Jul 2015 12:45:52 -0700, Eric Weaver
wrote:

On 7/14/15 4:13 PM, Jeff Liebermann wrote:
On Mon, 13 Jul 2015 13:45:43 +0200, "bilou" wrote:

There is not any proof that RF behaves differently than light.
Things are already quite complicated without it :-)

Sure there is. After half a century of exposure to RF, my hair is
falling out, my hand is shaking, and my bank account depleted. Other
people, who were only exposed to light, have not had these things
happen. I can only conclude that RF is somehow dangerous and
different from light.

That's gotta be it, by the infallible principle of Post Hoc Ergo Propter
Hoc.

Attributing my premature demise to the effects of RF exposure is
nothing new. It's done all the time by those that believe that
correlation is sufficient evidence to assign causation:
http://www.tylervigen.com/spurious-correlations
http://tylervigen.com/discover

It's a form of inductive logic. That's where one makes a series of
observations, and then contrives a generalized conclusion based upon
the available observations. For example, I've noticed that most of
the hams in the local radio club are officially senior citizens.
Therefore ham radio causes accelerated aging. It's all very logical.
The only problem is that inductive logic never really provides a proof
as there are always alternative explanations.

Fortunately, we have an easy test to identify fallacious correlations
called Occam's Razor, where the simplest explanation is usually the
correct explanation. In my case, RF exposure is a far more
complexicated explanation than simple aging. However, I discarded
that explanation due to lack of entertainment value. I also find it
easier to offer an intentionally complex theory that is easily
refuted, so that the simpler theory will be more readily accepted
without contest. Had I initially offered the simple theory, it would
surely have been met by opposition.

I hope this helps.

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

"Wayne" wrote in message
...
"The antenna, like the eye, is a transformation device converting
electromagnetic
photons into circuit currents; but, unlike the eye, the antenna can also
convert energy
from a circuit into photons radiated into space. In simplest terms an
antenna converts
photons to currents or vice versa." Antennas, Second Edition, 1988, by
John
D. Kraus. Page 19.

IMHO, antennae do not radiate photons. and the misunderstanding arises from
the photons that are generated from electrons shifting to lower energy
orbits around
atoms.

In tha case of currents within antennae, the energy is the potential energy
brought
about by compressing electrons against each other, against their inherent
mutual repulsion,
and is a different mechanism than that which generates photons.

gareth wrote:

"Wayne" wrote in message
...
"The antenna, like the eye, is a transformation device converting
electromagnetic
photons into circuit currents; but, unlike the eye, the antenna can also
convert energy
from a circuit into photons radiated into space. In simplest terms an
antenna converts
photons to currents or vice versa." Antennas, Second Edition, 1988, by
John
D. Kraus. Page 19.

IMHO, antennae do not radiate photons. and the misunderstanding arises from
the photons that are generated from electrons shifting to lower energy
orbits around
atoms.

In tha case of currents within antennae, the energy is the potential energy
brought
about by compressing electrons against each other, against their inherent
mutual repulsion,
and is a different mechanism than that which generates photons.

You come a little late to this discussion. Perhaps you would like to
explain, on the basis of your theory that there are two kinds of
electromagnetic radiation based on the means of their generation, how
you tell which kind of em radiation you are observing, the one which
also exists as photons or the one that doesn't? Preferably show the
answer mathematically.


--
Roger Hayter