Gentlemen,
Can some kind soul define what is meant by "moding" in terms of
microwave propagation - and is it a phenomenon not encountered at
lower RF frequencies?
Thanks,
CD.
On Fri, 01 Dec 2023 18:07:26 +0000, Cursitor Doom <cd@notformail.com>
wrote:
Gentlemen,
Can some kind soul define what is meant by "moding" in terms of
microwave propagation - and is it a phenomenon not encountered at
lower RF frequencies?
Thanks,
CD.
Waveguide moding is where a waveguide has resonances at frequencies
other than the intended one. A rectangular guide has horizontal and
vertical prop modes, plus all their harmonics. Google waveguide
moding.
A PCB trace, like a microstrip, has a resonant mode based on the gap
between the trace and the ground plane, but it's generally too high
frequency to worry about.
Coaxial cables have radial resonance modes that can be annoying. As
frequency goes up, the cable has to be smaller to avoid modes, but
small coaxes get lossy, so very high frequencies don't work on coax.
On Fri, 01 Dec 2023 11:11:48 -0800, john larkin <jl@650pot.com> wrote:
On Fri, 01 Dec 2023 18:07:26 +0000, Cursitor Doom <cd@notformail.com> >>wrote:
Gentlemen,
Can some kind soul define what is meant by "moding" in terms of
microwave propagation - and is it a phenomenon not encountered at
lower RF frequencies?
Thanks,
CD.
Waveguide moding is where a waveguide has resonances at frequencies
other than the intended one. A rectangular guide has horizontal and >>vertical prop modes, plus all their harmonics. Google waveguide
moding.
A PCB trace, like a microstrip, has a resonant mode based on the gap >>between the trace and the ground plane, but it's generally too high >>frequency to worry about.
Coaxial cables have radial resonance modes that can be annoying. As >>frequency goes up, the cable has to be smaller to avoid modes, but
small coaxes get lossy, so very high frequencies don't work on coax.
Thanks, John. I'm still confused as to the etymology of the term,
though. That particular aspect is still puzzling me....
On Fri, 01 Dec 2023 23:38:39 +0000, Cursitor Doom <cd@notformail.com>
wrote:
On Fri, 01 Dec 2023 11:11:48 -0800, john larkin <jl@650pot.com> wrote:
On Fri, 01 Dec 2023 18:07:26 +0000, Cursitor Doom <cd@notformail.com> >>>wrote:
Gentlemen,
Can some kind soul define what is meant by "moding" in terms of >>>>microwave propagation - and is it a phenomenon not encountered at
lower RF frequencies?
Thanks,
CD.
Waveguide moding is where a waveguide has resonances at frequencies
other than the intended one. A rectangular guide has horizontal and >>>vertical prop modes, plus all their harmonics. Google waveguide
moding.
A PCB trace, like a microstrip, has a resonant mode based on the gap >>>between the trace and the ground plane, but it's generally too high >>>frequency to worry about.
Coaxial cables have radial resonance modes that can be annoying. As >>>frequency goes up, the cable has to be smaller to avoid modes, but
small coaxes get lossy, so very high frequencies don't work on coax.
Thanks, John. I'm still confused as to the etymology of the term,
though. That particular aspect is still puzzling me....
It's from "propagation mode" which suggests that different electric
and magnetic field arrangements can transmit a wave.
https://resources.system-analysis.cadence.com/blog/msa2021-modes-of-wave-propagation-along-transmission-lines
The term is pretty general. It can refer to broadcast transmission,
sound waves, earthquakes, fiberoptic transmission, waveguides, coax,
all sorts of stuff.
"Moding" usually means some bad thing has happened because an
undesired mode is active. As in magnetron moding.
Samtec has a good pdf on moding.
On Fri, 01 Dec 2023 16:22:17 -0800, john larkin <jl@650pot.com> wrote:
On Fri, 01 Dec 2023 23:38:39 +0000, Cursitor Doom <cd@notformail.com> >>wrote:
On Fri, 01 Dec 2023 11:11:48 -0800, john larkin <jl@650pot.com> wrote:
On Fri, 01 Dec 2023 18:07:26 +0000, Cursitor Doom <cd@notformail.com> >>>>wrote:
Gentlemen,
Can some kind soul define what is meant by "moding" in terms of >>>>>microwave propagation - and is it a phenomenon not encountered at >>>>>lower RF frequencies?
Thanks,
CD.
Waveguide moding is where a waveguide has resonances at frequencies >>>>other than the intended one. A rectangular guide has horizontal and >>>>vertical prop modes, plus all their harmonics. Google waveguide >>>>moding.
A PCB trace, like a microstrip, has a resonant mode based on the gap >>>>between the trace and the ground plane, but it's generally too high >>>>frequency to worry about.
Coaxial cables have radial resonance modes that can be annoying. As >>>>frequency goes up, the cable has to be smaller to avoid modes, but >>>>small coaxes get lossy, so very high frequencies don't work on coax.
Thanks, John. I'm still confused as to the etymology of the term,
though. That particular aspect is still puzzling me....
It's from "propagation mode" which suggests that different electric
and magnetic field arrangements can transmit a wave.
https://resources.system-analysis.cadence.com/blog/msa2021-modes-of-wave-propagation-along-transmission-lines
The term is pretty general. It can refer to broadcast transmission,
sound waves, earthquakes, fiberoptic transmission, waveguides, coax,
all sorts of stuff.
"Moding" usually means some bad thing has happened because an
undesired mode is active. As in magnetron moding.
Samtec has a good pdf on moding.
I'll look it up. Thanks again.
On Sat, 02 Dec 2023 00:59:16 +0000, Cursitor Doom <cd@notformail.com>
wrote:
On Fri, 01 Dec 2023 16:22:17 -0800, john larkin <jl@650pot.com> wrote:
On Fri, 01 Dec 2023 23:38:39 +0000, Cursitor Doom <cd@notformail.com> >>>wrote:
On Fri, 01 Dec 2023 11:11:48 -0800, john larkin <jl@650pot.com> wrote:
On Fri, 01 Dec 2023 18:07:26 +0000, Cursitor Doom <cd@notformail.com> >>>>>wrote:
Gentlemen,
Can some kind soul define what is meant by "moding" in terms of >>>>>>microwave propagation - and is it a phenomenon not encountered at >>>>>>lower RF frequencies?
Thanks,
CD.
Waveguide moding is where a waveguide has resonances at frequencies >>>>>other than the intended one. A rectangular guide has horizontal and >>>>>vertical prop modes, plus all their harmonics. Google waveguide >>>>>moding.
A PCB trace, like a microstrip, has a resonant mode based on the gap >>>>>between the trace and the ground plane, but it's generally too high >>>>>frequency to worry about.
Coaxial cables have radial resonance modes that can be annoying. As >>>>>frequency goes up, the cable has to be smaller to avoid modes, but >>>>>small coaxes get lossy, so very high frequencies don't work on coax.
Thanks, John. I'm still confused as to the etymology of the term, >>>>though. That particular aspect is still puzzling me....
It's from "propagation mode" which suggests that different electric
and magnetic field arrangements can transmit a wave.
https://resources.system-analysis.cadence.com/blog/msa2021-modes-of-wave-propagation-along-transmission-lines
The term is pretty general. It can refer to broadcast transmission,
sound waves, earthquakes, fiberoptic transmission, waveguides, coax,
all sorts of stuff.
"Moding" usually means some bad thing has happened because an
undesired mode is active. As in magnetron moding.
Samtec has a good pdf on moding.
I'll look it up. Thanks again.
A couple of people have introduced 100 GHz sampling oscilloscopes,
using shock line impulse generators. They haven't lasted, which I
think is because 100 GHz electrical signals pretty much don't exist,
because of moding forcing coax to be uselessly small and lossy.
A couple of people have introduced 100 GHz sampling oscilloscopes,
using shock line impulse generators. They haven't lasted, which I
think is because 100 GHz electrical signals pretty much don't exist,
because of moding forcing coax to be uselessly small and lossy.
On Fri, 01 Dec 2023 21:09:16 -0800, John Larkin <jl@997PotHill.com>
wrote:
A couple of people have introduced 100 GHz sampling oscilloscopes,
using shock line impulse generators. They haven't lasted, which I
think is because 100 GHz electrical signals pretty much don't exist, >>because of moding forcing coax to be uselessly small and lossy.
Displaying a _repeating_ 100 GHz signal on a _sampled_ oscilloscope
should not be too hard. Sample the signal with 9 to 9.99 GHz clock and
the waveform can be displayed after 10 to 1000 cycles. The essential
thing is having a Sample/Hold circuit going from sample to hold in
less than 1 ps. The actual oscilloscope needs to be able operate at
only 10 MHz - 1000 MHz.
Generating microwaves and using waveguids is nothing new, a lot was >demonstrated before the year 1900. Signal generation and detecting up
to 60 GHz (5 mm) was demonstrated in that era.
See Wireless World: "Victorian microwaves" Sep 1979 p 93-95
https://worldradiohistory.com/UK/Wireless-World/70s/Wireless-World-1979-09.pdf
Sadly much of this was forgotten for half a century.
On Fri, 01 Dec 2023 21:09:16 -0800, John Larkin <jl@997PotHill.com>
wrote:
A couple of people have introduced 100 GHz sampling oscilloscopes,
using shock line impulse generators. They haven't lasted, which I think
is because 100 GHz electrical signals pretty much don't exist, because
of moding forcing coax to be uselessly small and lossy.
Displaying a _repeating_ 100 GHz signal on a _sampled_ oscilloscope
should not be too hard. Sample the signal with 9 to 9.99 GHz clock and
the waveform can be displayed after 10 to 1000 cycles. The essential
thing is having a Sample/Hold circuit going from sample to hold in
less than 1 ps. The actual oscilloscope needs to be able operate at
only 10 MHz - 1000 MHz.
Generating microwaves and using waveguids is nothing new, a lot was demonstrated before the year 1900. Signal generation and detecting up
to 60 GHz (5 mm) was demonstrated in that era.
See Wireless World: "Victorian microwaves" Sep 1979 p 93-95
https://worldradiohistory.com/UK/Wireless-World/70s/Wireless-World-1979-0 9.pdf
Sadly much of this was forgotten for half a century.
On Saturday, December 2, 2023 at 8:58:50?AM UTC-6, Anthony William Sloman wrote:small and lossy.
On Saturday, December 2, 2023 at 9:49:41?PM UTC+11, Cursitor Doom wrote:
On Fri, 01 Dec 2023 21:09:16 -0800, John Larkin <j...@997PotHill.com> wrote:<snip>
On Sat, 02 Dec 2023 00:59:16 +0000, Cursitor Doom <c...@notformail.com> wrote:
On Fri, 01 Dec 2023 16:22:17 -0800, john larkin <j...@650pot.com> wrote: >> > >>>On Fri, 01 Dec 2023 23:38:39 +0000, Cursitor Doom <c...@notformail.com> wrote:
On Fri, 01 Dec 2023 11:11:48 -0800, john larkin <j...@650pot.com> wrote:
On Fri, 01 Dec 2023 18:07:26 +0000, Cursitor Doom <c...@notformail.com> wrote:
A couple of people have introduced 100 GHz sampling oscilloscopes, using shock line impulse generators. They haven't lasted, which I think is because 100 GHz electrical signals pretty much don't exist, because of moding forcing coax to be uselessly
this term, which the author seems to assume the reader will already be familiar with.So you use wave-guides rather than coax.
Fortunately my RF interests have always been confined to the sub 100Mhz range - "practically DC" as they say. It's only because I was tipped-off that a book called Planar Microwave Engineering is the "AoE of RF" that I ordered a copy and came across
However, since I've previously been rooted to the domain where lumped element theory is sufficient, I've never encountered it.Neither have I. But it has been around for a while. Alan Blumlein died in 1942 in a bomber that crashed during an H2S flight test. You should at least have heard about it.
John Larkin probably hasn't.
Just couldn't resist could you?
https://en.wikipedia.org/wiki/Alan_Blumlein
https://en.wikipedia.org/wiki/H2S_(radar)
--
Bill Sloman, Sydney
On Sat, 2 Dec 2023 23:55:03 -0800 (PST), John Smihtuselessly small and lossy.
<utube.jocjo@xoxy.net> wrote:
On Saturday, December 2, 2023 at 8:58:50?AM UTC-6, Anthony William Sloman wrote:
On Saturday, December 2, 2023 at 9:49:41?PM UTC+11, Cursitor Doom wrote: >>> > On Fri, 01 Dec 2023 21:09:16 -0800, John Larkin <j...@997PotHill.com> wrote:
<snip>On Sat, 02 Dec 2023 00:59:16 +0000, Cursitor Doom <c...@notformail.com> wrote:
On Fri, 01 Dec 2023 16:22:17 -0800, john larkin <j...@650pot.com> wrote:
On Fri, 01 Dec 2023 23:38:39 +0000, Cursitor Doom <c...@notformail.com> wrote:
On Fri, 01 Dec 2023 11:11:48 -0800, john larkin <j...@650pot.com> wrote:
On Fri, 01 Dec 2023 18:07:26 +0000, Cursitor Doom <c...@notformail.com> wrote:
A couple of people have introduced 100 GHz sampling oscilloscopes, using shock line impulse generators. They haven't lasted, which I think is because 100 GHz electrical signals pretty much don't exist, because of moding forcing coax to be
across this term, which the author seems to assume the reader will already be familiar with.So you use wave-guides rather than coax.
Fortunately my RF interests have always been confined to the sub 100Mhz range - "practically DC" as they say. It's only because I was tipped-off that a book called Planar Microwave Engineering is the "AoE of RF" that I ordered a copy and came
However, since I've previously been rooted to the domain where lumped element theory is sufficient, I've never encountered it.Neither have I. But it has been around for a while. Alan Blumlein died in 1942 in a bomber that crashed during an H2S flight test. You should at least have heard about it.
John Larkin probably hasn't.
Just couldn't resist could you?
https://en.wikipedia.org/wiki/Alan_Blumlein
https://en.wikipedia.org/wiki/H2S_(radar)
--
Bill Sloman, Sydney
No, droning lame insults is his only joy. He doesn't design
electronics.
Blumline was brilliant. His death changed the world.
But waveguides aren't useful for transporting wideband, DC-coupled, >time-domain signals, which is what we do. Nowadays really fast signals
use light.
On Sun, 03 Dec 2023 08:28:19 -0800, John Larkin ><jjlarkin@highlandtechnology.com> wrote:uselessly small and lossy.
On Sat, 2 Dec 2023 23:55:03 -0800 (PST), John Smiht
<utube.jocjo@xoxy.net> wrote:
On Saturday, December 2, 2023 at 8:58:50?AM UTC-6, Anthony William Sloman wrote:
On Saturday, December 2, 2023 at 9:49:41?PM UTC+11, Cursitor Doom wrote: >>>> > On Fri, 01 Dec 2023 21:09:16 -0800, John Larkin <j...@997PotHill.com> wrote:
<snip>On Sat, 02 Dec 2023 00:59:16 +0000, Cursitor Doom <c...@notformail.com> wrote:
On Fri, 01 Dec 2023 16:22:17 -0800, john larkin <j...@650pot.com> wrote:
On Fri, 01 Dec 2023 23:38:39 +0000, Cursitor Doom <c...@notformail.com> wrote:
On Fri, 01 Dec 2023 11:11:48 -0800, john larkin <j...@650pot.com> wrote:
On Fri, 01 Dec 2023 18:07:26 +0000, Cursitor Doom <c...@notformail.com> wrote:
A couple of people have introduced 100 GHz sampling oscilloscopes, using shock line impulse generators. They haven't lasted, which I think is because 100 GHz electrical signals pretty much don't exist, because of moding forcing coax to be
across this term, which the author seems to assume the reader will already be familiar with.So you use wave-guides rather than coax.
Fortunately my RF interests have always been confined to the sub 100Mhz range - "practically DC" as they say. It's only because I was tipped-off that a book called Planar Microwave Engineering is the "AoE of RF" that I ordered a copy and came
However, since I've previously been rooted to the domain where lumped element theory is sufficient, I've never encountered it.Neither have I. But it has been around for a while. Alan Blumlein died in 1942 in a bomber that crashed during an H2S flight test. You should at least have heard about it.
John Larkin probably hasn't.
Just couldn't resist could you?
https://en.wikipedia.org/wiki/Alan_Blumlein
https://en.wikipedia.org/wiki/H2S_(radar)
--
Bill Sloman, Sydney
No, droning lame insults is his only joy. He doesn't design
electronics.
Blumline was brilliant. His death changed the world.
But waveguides aren't useful for transporting wideband, DC-coupled, >>time-domain signals, which is what we do. Nowadays really fast signals
use light.
Nowadays?
But waveguides aren't useful for transporting wideband, DC-coupled, >time-domain signals, which is what we do.
Waveguides are quite good high-pass filters. Some even use them as
part of EMP protection. A 2 m high and 1 m wide and tens of meters
long waveguide can be used as a corridor into a Faraday cage room. It
is simultaneously attenuating LF/MF/HF energy, where most EMP energy
is.
On Friday, December 1, 2023 at 1:07:41?PM UTC-5, Cursitor Doom wrote:thing only occurs when the physical dimensions of the transmission medium become comparable to the wavelength of the wave. And several different modes can exist, to greater and lesser degree, on the guided line simultaneously. Frequency dependent phasing
Gentlemen,
Can some kind soul define what is meant by "moding" in terms of
microwave propagation - and is it a phenomenon not encountered at
lower RF frequencies?
Thanks,
CD.
Cadence has this explanation on the subject, which was obviously slapped together by some idiot AI program. Generally speaking mode refers to how the E and M fields of the wave are oriented with respect to the direction of propagation. This type of
https://resources.system-analysis.cadence.com/blog/msa2021-modes-of-wave-propagation-along-transmission-lines
On Monday, December 4, 2023 at 3:25:37?AM UTC-5, John Larkin wrote:thing only occurs when the physical dimensions of the transmission medium become comparable to the wavelength of the wave. And several different modes can exist, to greater and lesser degree, on the guided line simultaneously. Frequency dependent phasing
On Sun, 3 Dec 2023 11:29:51 -0800 (PST), Fred Bloggs
<bloggs.fred...@gmail.com> wrote:
On Friday, December 1, 2023 at 1:07:41?PM UTC-5, Cursitor Doom wrote:
Gentlemen,
Can some kind soul define what is meant by "moding" in terms of
microwave propagation - and is it a phenomenon not encountered at
lower RF frequencies?
Thanks,
CD.
Cadence has this explanation on the subject, which was obviously slapped together by some idiot AI program. Generally speaking mode refers to how the E and M fields of the wave are oriented with respect to the direction of propagation. This type of
Waveguides are dispersive, so distort wideband signals. Worse than
https://resources.system-analysis.cadence.com/blog/msa2021-modes-of-wave-propagation-along-transmission-lines
microstrip or multimode fiber.
That's another reason to use an oscilloscope, with a coaxial cable
connector, to look at wideband signals. A waveguide is a highpass
filter, an ugly one, and coax (or microstrip, or fiber) is a lowpass
filter, a pretty good one.
Wherever there's loss, there's dispersion. You're not going to have much loss on short lengths of line on pcb's or probes, so not much dispersion.
Singlemode fiber is astounding. There are a lot of optical wavelengths
in 100 km.
Going back a few years, a lot of microwave to electro-optical converters became available with high performance linearity, > 70dB, and of course ultra-low loss compared to wires or waveguide at the frequencies they were pushing around.
<bloggs.fredbloggs.fred@gmail.com> wrote:than>>> microstrip or multimode fiber.
On Monday, December 4, 2023 at 3:25:37?AM UTC-5, John Larkin
wrote:
On Sun, 3 Dec 2023 11:29:51 -0800 (PST), Fred Bloggs
<bloggs.fred...@gmail.com> wrote:
On Friday, December 1, 2023 at 1:07:41?PM UTC-5, Cursitor Doom
wrote:
Gentlemen,
Can some kind soul define what is meant by "moding" in terms
of microwave propagation - and is it a phenomenon not
encountered at lower RF frequencies?
Thanks,
CD.
Cadence has this explanation on the subject, which was
obviously slapped together by some idiot AI program. Generally
speaking mode refers to how the E and M fields of the wave are
oriented with respect to the direction of propagation. This
type of thing only occurs when the physical dimensions of the
transmission medium become comparable to the wavelength of the
wave. And several different modes can exist, to greater and
lesser degree, on the guided line simultaneously. Frequency
dependent phasing of any intelligence being transmitted by the
wave can be seriously affected by the mode(s), degrading its
linearity, and that is usually not a good thing.
https://resources.system-analysis.cadence.com/blog/msa2021-modes-of-wave-propagation-along-transmission-lines
Waveguides are dispersive, so distort wideband signals. Worse
That's another reason to use an oscilloscope, with a coaxial
cable connector, to look at wideband signals. A waveguide is a
highpass filter, an ugly one, and coax (or microstrip, or fiber)
is a lowpass filter, a pretty good one.
Wherever there's loss, there's dispersion. You're not going to have
much loss on short lengths of line on pcb's or probes, so not much
dispersion.
Singlemode fiber is astounding. There are a lot of optical
wavelengths in 100 km.
Going back a few years, a lot of microwave to electro-optical
converters became available with high performance linearity, >
70dB, and of course ultra-low loss compared to wires or waveguide
at the frequencies they were pushing around.
We recently did a project, a time-domain optical modulator using
custom dual-stage lithium niobate modulators and expensive
distributed amplifiers.> The two legs of this mach-zender
interferometer are unequal length. That's OK if the light is very
coherent, but it makes for a bad tempco. So we built a gigantic,
massive oven for the modulator.
On 2023-12-04 13:05, John Larkin wrote:> On Mon, 4 Dec 2023 06:42:02
-0800 (PST), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:
https://resources.system-analysis.cadence.com/blog/msa2021-modes-of-wave-propagation-along-transmission-linesOn Monday, December 4, 2023 at 3:25:37?AM UTC-5, John Larkin
wrote:
On Sun, 3 Dec 2023 11:29:51 -0800 (PST), Fred Bloggs
<bloggs.fred...@gmail.com> wrote:
On Friday, December 1, 2023 at 1:07:41?PM UTC-5, Cursitor Doom
wrote:
Gentlemen,
Can some kind soul define what is meant by "moding" in terms
of microwave propagation - and is it a phenomenon not
encountered at lower RF frequencies?
Thanks,
CD.
Cadence has this explanation on the subject, which was
obviously slapped together by some idiot AI program. Generally
speaking mode refers to how the E and M fields of the wave are
oriented with respect to the direction of propagation. This
type of thing only occurs when the physical dimensions of the
transmission medium become comparable to the wavelength of the
wave. And several different modes can exist, to greater and
lesser degree, on the guided line simultaneously. Frequency
dependent phasing of any intelligence being transmitted by the
wave can be seriously affected by the mode(s), degrading its
linearity, and that is usually not a good thing.
than>>> microstrip or multimode fiber.
Waveguides are dispersive, so distort wideband signals. Worse
That's another reason to use an oscilloscope, with a coaxial
cable connector, to look at wideband signals. A waveguide is a
highpass filter, an ugly one, and coax (or microstrip, or fiber)
is a lowpass filter, a pretty good one.
Wherever there's loss, there's dispersion. You're not going to have
much loss on short lengths of line on pcb's or probes, so not much
dispersion.
Singlemode fiber is astounding. There are a lot of optical
wavelengths in 100 km.
Going back a few years, a lot of microwave to electro-optical
converters became available with high performance linearity, >
70dB, and of course ultra-low loss compared to wires or waveguide
at the frequencies they were pushing around.
We recently did a project, a time-domain optical modulator using
custom dual-stage lithium niobate modulators and expensive
distributed amplifiers.> The two legs of this mach-zender
interferometer are unequal length. That's OK if the light is very
coherent, but it makes for a bad tempco. So we built a gigantic,
massive oven for the modulator.
Oops, that's an expensive one. :(
On Mon, 4 Dec 2023 06:42:02 -0800 (PST), Fred Bloggs ><bloggs.fredbloggs.fred@gmail.com> wrote:
On Monday, December 4, 2023 at 3:25:37?AM UTC-5, John Larkin wrote:
On Sun, 3 Dec 2023 11:29:51 -0800 (PST), Fred Bloggs
<bloggs.fred...@gmail.com> wrote:
On Friday, December 1, 2023 at 1:07:41?PM UTC-5, Cursitor Doom wrote:Waveguides are dispersive, so distort wideband signals. Worse than
Gentlemen,
Can some kind soul define what is meant by "moding" in terms of
microwave propagation - and is it a phenomenon not encountered at
lower RF frequencies?
Thanks,
CD.
Cadence has this explanation on the subject, which was obviously slapped together by some idiot AI program. Generally
speaking mode refers to how the E and M fields of the wave are oriented with respect to the direction of propagation. This type of
thing only occurs when the physical dimensions of the transmission medium become comparable to the wavelength of the wave. And
several different modes can exist, to greater and lesser degree, on the guided line simultaneously. Frequency dependent phasing of
any intelligence being transmitted by the wave can be seriously affected by the mode(s), degrading its linearity, and that is
usually not a good thing.
https://resources.system-analysis.cadence.com/blog/msa2021-modes-of-wave-propagation-along-transmission-lines
microstrip or multimode fiber.
That's another reason to use an oscilloscope, with a coaxial cable
connector, to look at wideband signals. A waveguide is a highpass
filter, an ugly one, and coax (or microstrip, or fiber) is a lowpass
filter, a pretty good one.
Wherever there's loss, there's dispersion. You're not going to have much loss on short lengths of line on pcb's or probes, so
not much dispersion.
Singlemode fiber is astounding. There are a lot of optical wavelengths
in 100 km.
Going back a few years, a lot of microwave to electro-optical converters became available with high performance linearity, >
70dB, and of course ultra-low loss compared to wires or waveguide at the frequencies they were pushing around.
We recently did a project, a time-domain optical modulator using
custom dual-stage lithium niobate modulators and expensive distributed >amplifiers.
The two legs of this mach-zender interferometer are unequal length.
That's OK if the light is very coherent, but it makes for a bad
tempco. So we built a gigantic, massive oven for the modulator.
https://www.dropbox.com/s/29ttap9urihhep1/T500_Top_Final.jpg?raw=1
https://www.dropbox.com/s/f6h8tfyq0xkqx1q/Oven_Cables_pub.jpg?raw=1
https://www.dropbox.com/scl/fi/tb9ng8wo4oyz98y7y0gf2/Old_JD2.jpg?rlkey=2umu7cn25crqgj5zagctmc9x7&raw=1
Distributed amps are, like all RF parts, poorly characterized for
time-domain use. One has to experiment.
On a sunny day (Mon, 04 Dec 2023 10:05:33 -0800) it happened John Larkin ><jjlarkin@highlandtechnology.com> wrote in ><fhvrmipbb5diqs3na1gdoedirgnrbinf53@4ax.com>:
On Mon, 4 Dec 2023 06:42:02 -0800 (PST), Fred Bloggs >><bloggs.fredbloggs.fred@gmail.com> wrote:
On Monday, December 4, 2023 at 3:25:37?AM UTC-5, John Larkin wrote:
On Sun, 3 Dec 2023 11:29:51 -0800 (PST), Fred Bloggs
<bloggs.fred...@gmail.com> wrote:
On Friday, December 1, 2023 at 1:07:41?PM UTC-5, Cursitor Doom wrote: >>>> >> Gentlemen,Waveguides are dispersive, so distort wideband signals. Worse than
Can some kind soul define what is meant by "moding" in terms of
microwave propagation - and is it a phenomenon not encountered at
lower RF frequencies?
Thanks,
CD.
Cadence has this explanation on the subject, which was obviously slapped together by some idiot AI program. Generally
speaking mode refers to how the E and M fields of the wave are oriented with respect to the direction of propagation. This type of
thing only occurs when the physical dimensions of the transmission medium become comparable to the wavelength of the wave. And
several different modes can exist, to greater and lesser degree, on the guided line simultaneously. Frequency dependent phasing of
any intelligence being transmitted by the wave can be seriously affected by the mode(s), degrading its linearity, and that is
usually not a good thing.
https://resources.system-analysis.cadence.com/blog/msa2021-modes-of-wave-propagation-along-transmission-lines
microstrip or multimode fiber.
That's another reason to use an oscilloscope, with a coaxial cable
connector, to look at wideband signals. A waveguide is a highpass
filter, an ugly one, and coax (or microstrip, or fiber) is a lowpass
filter, a pretty good one.
Wherever there's loss, there's dispersion. You're not going to have much loss on short lengths of line on pcb's or probes, so
not much dispersion.
Singlemode fiber is astounding. There are a lot of optical wavelengths >>>> in 100 km.
Going back a few years, a lot of microwave to electro-optical converters became available with high performance linearity, >
70dB, and of course ultra-low loss compared to wires or waveguide at the frequencies they were pushing around.
We recently did a project, a time-domain optical modulator using
custom dual-stage lithium niobate modulators and expensive distributed >>amplifiers.
The two legs of this mach-zender interferometer are unequal length.
That's OK if the light is very coherent, but it makes for a bad
tempco. So we built a gigantic, massive oven for the modulator.
https://www.dropbox.com/s/29ttap9urihhep1/T500_Top_Final.jpg?raw=1
https://www.dropbox.com/s/f6h8tfyq0xkqx1q/Oven_Cables_pub.jpg?raw=1
https://www.dropbox.com/scl/fi/tb9ng8wo4oyz98y7y0gf2/Old_JD2.jpg?rlkey=2umu7cn25crqgj5zagctmc9x7&raw=1
Distributed amps are, like all RF parts, poorly characterized for >>time-domain use. One has to experiment.
The price of gold has gone up significally / peaked the last few days :-)
On Tue, 05 Dec 2023 05:12:47 GMT, Jan Panteltje <alien@comet.invalid>
wrote:
On a sunny day (Mon, 04 Dec 2023 10:05:33 -0800) it happened John Larkin >><jjlarkin@highlandtechnology.com> wrote in >><fhvrmipbb5diqs3na1gdoedirgnrbinf53@4ax.com>:
On Mon, 4 Dec 2023 06:42:02 -0800 (PST), Fred Bloggs >>><bloggs.fredbloggs.fred@gmail.com> wrote:
On Monday, December 4, 2023 at 3:25:37?AM UTC-5, John Larkin wrote:
On Sun, 3 Dec 2023 11:29:51 -0800 (PST), Fred Bloggs
<bloggs.fred...@gmail.com> wrote:
On Friday, December 1, 2023 at 1:07:41?PM UTC-5, Cursitor Doom wrote: >>>>> >> Gentlemen,Waveguides are dispersive, so distort wideband signals. Worse than
Can some kind soul define what is meant by "moding" in terms of
microwave propagation - and is it a phenomenon not encountered at >>>>> >> lower RF frequencies?
Thanks,
CD.
Cadence has this explanation on the subject, which was obviously slapped together by some idiot AI program. Generally
speaking mode refers to how the E and M fields of the wave are oriented with respect to the direction of propagation. This type of
thing only occurs when the physical dimensions of the transmission medium become comparable to the wavelength of the wave. And
several different modes can exist, to greater and lesser degree, on the guided line simultaneously. Frequency dependent phasing of
any intelligence being transmitted by the wave can be seriously affected by the mode(s), degrading its linearity, and that is
usually not a good thing.
https://resources.system-analysis.cadence.com/blog/msa2021-modes-of-wave-propagation-along-transmission-lines
microstrip or multimode fiber.
That's another reason to use an oscilloscope, with a coaxial cable
connector, to look at wideband signals. A waveguide is a highpass
filter, an ugly one, and coax (or microstrip, or fiber) is a lowpass >>>>> filter, a pretty good one.
Wherever there's loss, there's dispersion. You're not going to have much loss on short lengths of line on pcb's or probes, so
not much dispersion.
Singlemode fiber is astounding. There are a lot of optical wavelengths >>>>> in 100 km.
Going back a few years, a lot of microwave to electro-optical converters became available with high performance linearity, >
70dB, and of course ultra-low loss compared to wires or waveguide at the frequencies they were pushing around.
We recently did a project, a time-domain optical modulator using
custom dual-stage lithium niobate modulators and expensive distributed >>>amplifiers.
The two legs of this mach-zender interferometer are unequal length. >>>That's OK if the light is very coherent, but it makes for a bad
tempco. So we built a gigantic, massive oven for the modulator.
https://www.dropbox.com/s/29ttap9urihhep1/T500_Top_Final.jpg?raw=1
https://www.dropbox.com/s/f6h8tfyq0xkqx1q/Oven_Cables_pub.jpg?raw=1
https://www.dropbox.com/scl/fi/tb9ng8wo4oyz98y7y0gf2/Old_JD2.jpg?rlkey=2umu7cn25crqgj5zagctmc9x7&raw=1
Distributed amps are, like all RF parts, poorly characterized for >>>time-domain use. One has to experiment.
The price of gold has gone up significally / peaked the last few days :-)
HMC659 must have a lot of it inside.
On Mon, 4 Dec 2023 15:20:12 -0500, Phil Hobbs ><pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2023-12-04 13:05, John Larkin wrote:> On Mon, 4 Dec 2023 06:42:02
-0800 (PST), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:than>>> microstrip or multimode fiber.
On Monday, December 4, 2023 at 3:25:37?AM UTC-5, John Larkin
wrote:
On Sun, 3 Dec 2023 11:29:51 -0800 (PST), Fred Bloggs
<bloggs.fred...@gmail.com> wrote:
On Friday, December 1, 2023 at 1:07:41?PM UTC-5, Cursitor Doom
wrote:
Gentlemen,
Can some kind soul define what is meant by "moding" in terms
of microwave propagation - and is it a phenomenon not
encountered at lower RF frequencies?
Thanks,
CD.
Cadence has this explanation on the subject, which was
obviously slapped together by some idiot AI program. Generally
speaking mode refers to how the E and M fields of the wave are
oriented with respect to the direction of propagation. This
type of thing only occurs when the physical dimensions of the
transmission medium become comparable to the wavelength of the
wave. And several different modes can exist, to greater and
lesser degree, on the guided line simultaneously. Frequency
dependent phasing of any intelligence being transmitted by the
wave can be seriously affected by the mode(s), degrading its
linearity, and that is usually not a good thing.
https://resources.system-analysis.cadence.com/blog/msa2021-modes-of-wave-propagation-along-transmission-lines
Waveguides are dispersive, so distort wideband signals. Worse
That's another reason to use an oscilloscope, with a coaxial
cable connector, to look at wideband signals. A waveguide is a
highpass filter, an ugly one, and coax (or microstrip, or fiber)
is a lowpass filter, a pretty good one.
Wherever there's loss, there's dispersion. You're not going to have
much loss on short lengths of line on pcb's or probes, so not much
dispersion.
Singlemode fiber is astounding. There are a lot of optical
wavelengths in 100 km.
Going back a few years, a lot of microwave to electro-optical
converters became available with high performance linearity, >
70dB, and of course ultra-low loss compared to wires or waveguide
at the frequencies they were pushing around.
We recently did a project, a time-domain optical modulator using
custom dual-stage lithium niobate modulators and expensive
distributed amplifiers.> The two legs of this mach-zender
interferometer are unequal length. That's OK if the light is very
coherent, but it makes for a bad tempco. So we built a gigantic,
massive oven for the modulator.
Oops, that's an expensive one. :(
Customer furnished!
I have a new (or at least new to me) way of biasing distributed
amplifiers for making big pulses into an EOM. Anyone interested can
contact me.
On Mon, 04 Dec 2023 17:41:04 -0800, John Larkin <jl@997PotHill.com>
wrote:
On Mon, 4 Dec 2023 15:20:12 -0500, Phil Hobbs >><pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2023-12-04 13:05, John Larkin wrote:> On Mon, 4 Dec 2023 06:42:02 >>>-0800 (PST), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:
On Monday, December 4, 2023 at 3:25:37?AM UTC-5, John Larkin
wrote:
On Sun, 3 Dec 2023 11:29:51 -0800 (PST), Fred Bloggs
<bloggs.fred...@gmail.com> wrote:
On Friday, December 1, 2023 at 1:07:41?PM UTC-5, Cursitor Doom
wrote:
Gentlemen,
Can some kind soul define what is meant by "moding" in terms
of microwave propagation - and is it a phenomenon not
encountered at lower RF frequencies?
Thanks,
CD.
Cadence has this explanation on the subject, which was
obviously slapped together by some idiot AI program. Generally
speaking mode refers to how the E and M fields of the wave are
oriented with respect to the direction of propagation. This
type of thing only occurs when the physical dimensions of the
transmission medium become comparable to the wavelength of the
wave. And several different modes can exist, to greater and
lesser degree, on the guided line simultaneously. Frequency
dependent phasing of any intelligence being transmitted by the
wave can be seriously affected by the mode(s), degrading its
linearity, and that is usually not a good thing.
https://resources.system-analysis.cadence.com/blog/msa2021-modes-of-wave-propagation-along-transmission-lines
Waveguides are dispersive, so distort wideband signals. Worse >>>than>>> microstrip or multimode fiber.
That's another reason to use an oscilloscope, with a coaxial
cable connector, to look at wideband signals. A waveguide is a
highpass filter, an ugly one, and coax (or microstrip, or fiber)
is a lowpass filter, a pretty good one.
Wherever there's loss, there's dispersion. You're not going to have
much loss on short lengths of line on pcb's or probes, so not much
dispersion.
Singlemode fiber is astounding. There are a lot of optical
wavelengths in 100 km.
Going back a few years, a lot of microwave to electro-optical
converters became available with high performance linearity, >
70dB, and of course ultra-low loss compared to wires or waveguide
at the frequencies they were pushing around.
We recently did a project, a time-domain optical modulator using
custom dual-stage lithium niobate modulators and expensive
distributed amplifiers.> The two legs of this mach-zender
interferometer are unequal length. That's OK if the light is very
coherent, but it makes for a bad tempco. So we built a gigantic,
massive oven for the modulator.
Oops, that's an expensive one. :(
Customer furnished!
I have a new (or at least new to me) way of biasing distributed
amplifiers for making big pulses into an EOM. Anyone interested can
contact me.
What's goin' on here, John? You always said you hated RF and regarded
it as a black art and now you seem to have at least become very >well-acquainted with it - and at microwave frequencies, too! Even the
likes of Phil Hobbs haven't found fault with your pronouncements.
Jolly well done. Autodidactic approach to the subject, I'm guessing?
On Fri, 08 Dec 2023 18:10:01 +0000, Cursitor Doom <cd@notformail.com>
wrote:
On Mon, 04 Dec 2023 17:41:04 -0800, John Larkin <jl@997PotHill.com>
wrote:
On Mon, 4 Dec 2023 15:20:12 -0500, Phil Hobbs >>><pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2023-12-04 13:05, John Larkin wrote:> On Mon, 4 Dec 2023 06:42:02 >>>>-0800 (PST), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:
On Monday, December 4, 2023 at 3:25:37?AM UTC-5, John Larkin
wrote:
On Sun, 3 Dec 2023 11:29:51 -0800 (PST), Fred Bloggs
<bloggs.fred...@gmail.com> wrote:
On Friday, December 1, 2023 at 1:07:41?PM UTC-5, Cursitor Doom
wrote:
Gentlemen,
Can some kind soul define what is meant by "moding" in terms
of microwave propagation - and is it a phenomenon not
encountered at lower RF frequencies?
Thanks,
CD.
Cadence has this explanation on the subject, which was
obviously slapped together by some idiot AI program. Generally
speaking mode refers to how the E and M fields of the wave are
oriented with respect to the direction of propagation. This
type of thing only occurs when the physical dimensions of the
transmission medium become comparable to the wavelength of the
wave. And several different modes can exist, to greater and
lesser degree, on the guided line simultaneously. Frequency
dependent phasing of any intelligence being transmitted by the
wave can be seriously affected by the mode(s), degrading its
linearity, and that is usually not a good thing.
https://resources.system-analysis.cadence.com/blog/msa2021-modes-of-wave-propagation-along-transmission-lines
Waveguides are dispersive, so distort wideband signals. Worse >>>>than>>> microstrip or multimode fiber.
That's another reason to use an oscilloscope, with a coaxial
cable connector, to look at wideband signals. A waveguide is a
highpass filter, an ugly one, and coax (or microstrip, or fiber)
is a lowpass filter, a pretty good one.
Wherever there's loss, there's dispersion. You're not going to have >>>> >> much loss on short lengths of line on pcb's or probes, so not much
dispersion.
Singlemode fiber is astounding. There are a lot of optical
wavelengths in 100 km.
Going back a few years, a lot of microwave to electro-optical
converters became available with high performance linearity, >
70dB, and of course ultra-low loss compared to wires or waveguide
at the frequencies they were pushing around.
We recently did a project, a time-domain optical modulator using
custom dual-stage lithium niobate modulators and expensive
distributed amplifiers.> The two legs of this mach-zender
interferometer are unequal length. That's OK if the light is very
coherent, but it makes for a bad tempco. So we built a gigantic,
massive oven for the modulator.
Oops, that's an expensive one. :(
Customer furnished!
I have a new (or at least new to me) way of biasing distributed >>>amplifiers for making big pulses into an EOM. Anyone interested can >>>contact me.
What's goin' on here, John? You always said you hated RF and regarded
it as a black art and now you seem to have at least become very >>well-acquainted with it - and at microwave frequencies, too! Even the
likes of Phil Hobbs haven't found fault with your pronouncements.
Jolly well done. Autodidactic approach to the subject, I'm guessing?
I do despise sine waves, s-params, noise figures, and Smith charts.
They are all legacies of the slide rule days.
I do use "RF" parts in fast, wideband, time domain products. The data
sheets are often deceptive, so I test and characterize the parts
myself, and sometimes hack Spice models.
Two annoyances:
When a frequency response graph stops at some low frequency, you can
expect that something weird is being hidden, like a slow internal bias
loop. We used one absorptive RF switch part whose claimed LF response
is "DC" and actually didn't work right below about 100 MHz. I spoke to
the chip designer about the LF behavior and he wouldn't discuss it
because it's "proprietary". That was Maxim.
Many RF devices assume that some Vcc is connected to their output
through an inductor. So in reality they expect 2*Vcc as an instaneous
sine peak voltage, double the abs max spec. I test them to destruction
(at $300 each!) and back off some.
On Fri, 08 Dec 2023 22:41:19 +0000, Cursitor Doom <cd@notformail.com>
wrote:
On Fri, 08 Dec 2023 12:22:55 -0800, john larkin <jl@650pot.com> wrote:
On Fri, 08 Dec 2023 18:10:01 +0000, Cursitor Doom <cd@notformail.com> >>>wrote:
On Mon, 04 Dec 2023 17:41:04 -0800, John Larkin <jl@997PotHill.com> >>>>wrote:
On Mon, 4 Dec 2023 15:20:12 -0500, Phil Hobbs >>>>><pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2023-12-04 13:05, John Larkin wrote:> On Mon, 4 Dec 2023 06:42:02 >>>>>>-0800 (PST), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:
On Monday, December 4, 2023 at 3:25:37?AM UTC-5, John Larkin
wrote:
On Sun, 3 Dec 2023 11:29:51 -0800 (PST), Fred Bloggs
<bloggs.fred...@gmail.com> wrote:
On Friday, December 1, 2023 at 1:07:41?PM UTC-5, Cursitor Doom >>>>>> >>>> wrote:
Gentlemen,
Can some kind soul define what is meant by "moding" in terms >>>>>> >>>>> of microwave propagation - and is it a phenomenon not
encountered at lower RF frequencies?
Thanks,
CD.
Cadence has this explanation on the subject, which was
obviously slapped together by some idiot AI program. Generally >>>>>> >>>> speaking mode refers to how the E and M fields of the wave are >>>>>> >>>> oriented with respect to the direction of propagation. This
type of thing only occurs when the physical dimensions of the >>>>>> >>>> transmission medium become comparable to the wavelength of the >>>>>> >>>> wave. And several different modes can exist, to greater and
lesser degree, on the guided line simultaneously. Frequency
dependent phasing of any intelligence being transmitted by the >>>>>> >>>> wave can be seriously affected by the mode(s), degrading its >>>>>> >>>> linearity, and that is usually not a good thing.
https://resources.system-analysis.cadence.com/blog/msa2021-modes-of-wave-propagation-along-transmission-lines
Waveguides are dispersive, so distort wideband signals. Worse >>>>>>than>>> microstrip or multimode fiber.
That's another reason to use an oscilloscope, with a coaxial
cable connector, to look at wideband signals. A waveguide is a >>>>>> >>> highpass filter, an ugly one, and coax (or microstrip, or fiber) >>>>>> >>> is a lowpass filter, a pretty good one.
Wherever there's loss, there's dispersion. You're not going to have >>>>>> >> much loss on short lengths of line on pcb's or probes, so not much >>>>>> >> dispersion.
Singlemode fiber is astounding. There are a lot of optical
wavelengths in 100 km.
Going back a few years, a lot of microwave to electro-optical
converters became available with high performance linearity, >
70dB, and of course ultra-low loss compared to wires or waveguide >>>>>> >> at the frequencies they were pushing around.
We recently did a project, a time-domain optical modulator using >>>>>> > custom dual-stage lithium niobate modulators and expensive
distributed amplifiers.> The two legs of this mach-zender
interferometer are unequal length. That's OK if the light is very >>>>>> > coherent, but it makes for a bad tempco. So we built a gigantic, >>>>>> > massive oven for the modulator.
Oops, that's an expensive one. :(
Customer furnished!
I have a new (or at least new to me) way of biasing distributed >>>>>amplifiers for making big pulses into an EOM. Anyone interested can >>>>>contact me.
What's goin' on here, John? You always said you hated RF and regarded >>>>it as a black art and now you seem to have at least become very >>>>well-acquainted with it - and at microwave frequencies, too! Even the >>>>likes of Phil Hobbs haven't found fault with your pronouncements.
Jolly well done. Autodidactic approach to the subject, I'm guessing?
I do despise sine waves, s-params, noise figures, and Smith charts.
They are all legacies of the slide rule days.
I do use "RF" parts in fast, wideband, time domain products. The data >>>sheets are often deceptive, so I test and characterize the parts
myself, and sometimes hack Spice models.
Two annoyances:
When a frequency response graph stops at some low frequency, you can >>>expect that something weird is being hidden, like a slow internal bias >>>loop. We used one absorptive RF switch part whose claimed LF response
is "DC" and actually didn't work right below about 100 MHz. I spoke to >>>the chip designer about the LF behavior and he wouldn't discuss it >>>because it's "proprietary". That was Maxim.
Many RF devices assume that some Vcc is connected to their output
through an inductor. So in reality they expect 2*Vcc as an instaneous >>>sine peak voltage, double the abs max spec. I test them to destruction >>>(at $300 each!) and back off some.
Decent test equipment for those kind of frequencies is horrifically >>expensive, so I have no idea how you can justify forking out that kind
of money given that this kind of development is outside your usual
line of activity.
Our usual line of activity is picosecond electronics.
Do you just hire some in when you need it on an ad
hoc basis?
500 MHz oscilloscopes, and 30 GHz sampling scopes, are affordable. I
don't think we have ever rented test equipment. We don't work in
frequency bands, so don't need a range of things.
It's annoying that part and equipment suppliers expect their customers
to be working in one frequency band. I'm seeing that a lot lately in
ICs and even fets. I guess they are tuning wire bonds and such for one >market.
People are labeling the pins of fets RF IN RF OUT GROUND instead
of gate, drain, source. DC specs are "adjust the RF port bias trimpot
until it works."
On Fri, 08 Dec 2023 12:22:55 -0800, john larkin <jl@650pot.com> wrote:
On Fri, 08 Dec 2023 18:10:01 +0000, Cursitor Doom <cd@notformail.com> >>wrote:
On Mon, 04 Dec 2023 17:41:04 -0800, John Larkin <jl@997PotHill.com> >>>wrote:
On Mon, 4 Dec 2023 15:20:12 -0500, Phil Hobbs >>>><pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2023-12-04 13:05, John Larkin wrote:> On Mon, 4 Dec 2023 06:42:02 >>>>>-0800 (PST), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:
On Monday, December 4, 2023 at 3:25:37?AM UTC-5, John Larkin
wrote:
On Sun, 3 Dec 2023 11:29:51 -0800 (PST), Fred Bloggs
<bloggs.fred...@gmail.com> wrote:
On Friday, December 1, 2023 at 1:07:41?PM UTC-5, Cursitor Doom
wrote:
Gentlemen,
Can some kind soul define what is meant by "moding" in terms
of microwave propagation - and is it a phenomenon not
encountered at lower RF frequencies?
Thanks,
CD.
Cadence has this explanation on the subject, which was
obviously slapped together by some idiot AI program. Generally
speaking mode refers to how the E and M fields of the wave are >>>>> >>>> oriented with respect to the direction of propagation. This
type of thing only occurs when the physical dimensions of the
transmission medium become comparable to the wavelength of the
wave. And several different modes can exist, to greater and
lesser degree, on the guided line simultaneously. Frequency
dependent phasing of any intelligence being transmitted by the
wave can be seriously affected by the mode(s), degrading its
linearity, and that is usually not a good thing.
https://resources.system-analysis.cadence.com/blog/msa2021-modes-of-wave-propagation-along-transmission-lines
Waveguides are dispersive, so distort wideband signals. Worse >>>>>than>>> microstrip or multimode fiber.
That's another reason to use an oscilloscope, with a coaxial
cable connector, to look at wideband signals. A waveguide is a
highpass filter, an ugly one, and coax (or microstrip, or fiber) >>>>> >>> is a lowpass filter, a pretty good one.
Wherever there's loss, there's dispersion. You're not going to have >>>>> >> much loss on short lengths of line on pcb's or probes, so not much >>>>> >> dispersion.
Singlemode fiber is astounding. There are a lot of optical
wavelengths in 100 km.
Going back a few years, a lot of microwave to electro-optical
converters became available with high performance linearity, >
70dB, and of course ultra-low loss compared to wires or waveguide >>>>> >> at the frequencies they were pushing around.
We recently did a project, a time-domain optical modulator using
custom dual-stage lithium niobate modulators and expensive
distributed amplifiers.> The two legs of this mach-zender
interferometer are unequal length. That's OK if the light is very
coherent, but it makes for a bad tempco. So we built a gigantic,
massive oven for the modulator.
Oops, that's an expensive one. :(
Customer furnished!
I have a new (or at least new to me) way of biasing distributed >>>>amplifiers for making big pulses into an EOM. Anyone interested can >>>>contact me.
What's goin' on here, John? You always said you hated RF and regarded
it as a black art and now you seem to have at least become very >>>well-acquainted with it - and at microwave frequencies, too! Even the >>>likes of Phil Hobbs haven't found fault with your pronouncements.
Jolly well done. Autodidactic approach to the subject, I'm guessing?
I do despise sine waves, s-params, noise figures, and Smith charts.
They are all legacies of the slide rule days.
I do use "RF" parts in fast, wideband, time domain products. The data >>sheets are often deceptive, so I test and characterize the parts
myself, and sometimes hack Spice models.
Two annoyances:
When a frequency response graph stops at some low frequency, you can
expect that something weird is being hidden, like a slow internal bias >>loop. We used one absorptive RF switch part whose claimed LF response
is "DC" and actually didn't work right below about 100 MHz. I spoke to
the chip designer about the LF behavior and he wouldn't discuss it
because it's "proprietary". That was Maxim.
Many RF devices assume that some Vcc is connected to their output
through an inductor. So in reality they expect 2*Vcc as an instaneous
sine peak voltage, double the abs max spec. I test them to destruction
(at $300 each!) and back off some.
Decent test equipment for those kind of frequencies is horrifically >expensive, so I have no idea how you can justify forking out that kind
of money given that this kind of development is outside your usual
line of activity.
Do you just hire some in when you need it on an ad
hoc basis?
On Mon, 04 Dec 2023 21:34:51 -0800, John Larkin <jl@997PotHill.com>
wrote:
On Tue, 05 Dec 2023 05:12:47 GMT, Jan Panteltje <alien@comet.invalid> >>wrote:
On a sunny day (Mon, 04 Dec 2023 10:05:33 -0800) it happened John Larkin >>><jjlarkin@highlandtechnology.com> wrote in >>><fhvrmipbb5diqs3na1gdoedirgnrbinf53@4ax.com>:
On Mon, 4 Dec 2023 06:42:02 -0800 (PST), Fred Bloggs >>>><bloggs.fredbloggs.fred@gmail.com> wrote:
On Monday, December 4, 2023 at 3:25:37?AM UTC-5, John Larkin wrote:
On Sun, 3 Dec 2023 11:29:51 -0800 (PST), Fred Bloggs
<bloggs.fred...@gmail.com> wrote:
On Friday, December 1, 2023 at 1:07:41?PM UTC-5, Cursitor Doom wrote: >>>>>> >> Gentlemen,Waveguides are dispersive, so distort wideband signals. Worse than >>>>>> microstrip or multimode fiber.
Can some kind soul define what is meant by "moding" in terms of >>>>>> >> microwave propagation - and is it a phenomenon not encountered at >>>>>> >> lower RF frequencies?
Thanks,
CD.
Cadence has this explanation on the subject, which was obviously slapped together by some idiot AI program. Generally
speaking mode refers to how the E and M fields of the wave are oriented with respect to the direction of propagation.
This type of
thing only occurs when the physical dimensions of the transmission medium become comparable to the wavelength of the
wave. And
several different modes can exist, to greater and lesser degree, on the guided line simultaneously. Frequency dependent
phasing of
any intelligence being transmitted by the wave can be seriously affected by the mode(s), degrading its linearity, and
that is
usually not a good thing.
https://resources.system-analysis.cadence.com/blog/msa2021-modes-of-wave-propagation-along-transmission-lines
That's another reason to use an oscilloscope, with a coaxial cable >>>>>> connector, to look at wideband signals. A waveguide is a highpass
filter, an ugly one, and coax (or microstrip, or fiber) is a lowpass >>>>>> filter, a pretty good one.
Wherever there's loss, there's dispersion. You're not going to have much loss on short lengths of line on pcb's or probes,
so
not much dispersion.
Singlemode fiber is astounding. There are a lot of optical wavelengths >>>>>> in 100 km.
Going back a few years, a lot of microwave to electro-optical converters became available with high performance linearity,
70dB, and of course ultra-low loss compared to wires or waveguide at the frequencies they were pushing around.
We recently did a project, a time-domain optical modulator using
custom dual-stage lithium niobate modulators and expensive distributed >>>>amplifiers.
The two legs of this mach-zender interferometer are unequal length. >>>>That's OK if the light is very coherent, but it makes for a bad
tempco. So we built a gigantic, massive oven for the modulator.
https://www.dropbox.com/s/29ttap9urihhep1/T500_Top_Final.jpg?raw=1
https://www.dropbox.com/s/f6h8tfyq0xkqx1q/Oven_Cables_pub.jpg?raw=1
https://www.dropbox.com/scl/fi/tb9ng8wo4oyz98y7y0gf2/Old_JD2.jpg?rlkey=2umu7cn25crqgj5zagctmc9x7&raw=1
Distributed amps are, like all RF parts, poorly characterized for >>>>time-domain use. One has to experiment.
The price of gold has gone up significally / peaked the last few days :-)
Got whacked back down again pretty sharpish by the paper contract
dumpers, though! You might almost think they're rigging the market.
On a sunny day (Fri, 08 Dec 2023 17:59:01 +0000) it happened Cursitor Doom ><cd@notformail.com> wrote in <79m6nids8r273stl9od79bvk18g67b5gfq@4ax.com>:
On Mon, 04 Dec 2023 21:34:51 -0800, John Larkin <jl@997PotHill.com>
wrote:
On Tue, 05 Dec 2023 05:12:47 GMT, Jan Panteltje <alien@comet.invalid> >>>wrote:Got whacked back down again pretty sharpish by the paper contract
On a sunny day (Mon, 04 Dec 2023 10:05:33 -0800) it happened John Larkin >>>><jjlarkin@highlandtechnology.com> wrote in >>>><fhvrmipbb5diqs3na1gdoedirgnrbinf53@4ax.com>:
On Mon, 4 Dec 2023 06:42:02 -0800 (PST), Fred Bloggs >>>>><bloggs.fredbloggs.fred@gmail.com> wrote:
On Monday, December 4, 2023 at 3:25:37?AM UTC-5, John Larkin wrote: >>>>>>> On Sun, 3 Dec 2023 11:29:51 -0800 (PST), Fred Bloggs
<bloggs.fred...@gmail.com> wrote:
On Friday, December 1, 2023 at 1:07:41?PM UTC-5, Cursitor Doom wrote: >>>>>>> >> Gentlemen,Waveguides are dispersive, so distort wideband signals. Worse than >>>>>>> microstrip or multimode fiber.
Can some kind soul define what is meant by "moding" in terms of >>>>>>> >> microwave propagation - and is it a phenomenon not encountered at >>>>>>> >> lower RF frequencies?
Thanks,
CD.
Cadence has this explanation on the subject, which was obviously slapped together by some idiot AI program. Generally
speaking mode refers to how the E and M fields of the wave are oriented with respect to the direction of propagation.
This type of
thing only occurs when the physical dimensions of the transmission medium become comparable to the wavelength of the
wave. And
several different modes can exist, to greater and lesser degree, on the guided line simultaneously. Frequency dependent
phasing of
any intelligence being transmitted by the wave can be seriously affected by the mode(s), degrading its linearity, and
that is
usually not a good thing.
https://resources.system-analysis.cadence.com/blog/msa2021-modes-of-wave-propagation-along-transmission-lines
That's another reason to use an oscilloscope, with a coaxial cable >>>>>>> connector, to look at wideband signals. A waveguide is a highpass >>>>>>> filter, an ugly one, and coax (or microstrip, or fiber) is a lowpass >>>>>>> filter, a pretty good one.
Wherever there's loss, there's dispersion. You're not going to have much loss on short lengths of line on pcb's or probes,
so
not much dispersion.
Singlemode fiber is astounding. There are a lot of optical wavelengths >>>>>>> in 100 km.
Going back a few years, a lot of microwave to electro-optical converters became available with high performance linearity,
70dB, and of course ultra-low loss compared to wires or waveguide at the frequencies they were pushing around.
We recently did a project, a time-domain optical modulator using >>>>>custom dual-stage lithium niobate modulators and expensive distributed >>>>>amplifiers.
The two legs of this mach-zender interferometer are unequal length. >>>>>That's OK if the light is very coherent, but it makes for a bad >>>>>tempco. So we built a gigantic, massive oven for the modulator.
https://www.dropbox.com/s/29ttap9urihhep1/T500_Top_Final.jpg?raw=1
https://www.dropbox.com/s/f6h8tfyq0xkqx1q/Oven_Cables_pub.jpg?raw=1
https://www.dropbox.com/scl/fi/tb9ng8wo4oyz98y7y0gf2/Old_JD2.jpg?rlkey=2umu7cn25crqgj5zagctmc9x7&raw=1
Distributed amps are, like all RF parts, poorly characterized for >>>>>time-domain use. One has to experiment.
The price of gold has gone up significally / peaked the last few days :-) >>
dumpers, though! You might almost think they're rigging the market.
Good time to buy!
The war in Gaza may escalate and then gold will be worth a lot.
https://goldprice.org/live-gold-price.html
On Sat, 09 Dec 2023 07:06:09 GMT, Jan Panteltje <alien@comet.invalid>
wrote:
On a sunny day (Fri, 08 Dec 2023 17:59:01 +0000) it happened Cursitor Doom >><cd@notformail.com> wrote in <79m6nids8r273stl9od79bvk18g67b5gfq@4ax.com>:
On Mon, 04 Dec 2023 21:34:51 -0800, John Larkin <jl@997PotHill.com> >>>wrote:
On Tue, 05 Dec 2023 05:12:47 GMT, Jan Panteltje <alien@comet.invalid> >>>>wrote:Got whacked back down again pretty sharpish by the paper contract >>>dumpers, though! You might almost think they're rigging the market.
On a sunny day (Mon, 04 Dec 2023 10:05:33 -0800) it happened John Larkin >>>>><jjlarkin@highlandtechnology.com> wrote in >>>>><fhvrmipbb5diqs3na1gdoedirgnrbinf53@4ax.com>:
On Mon, 4 Dec 2023 06:42:02 -0800 (PST), Fred Bloggs >>>>>><bloggs.fredbloggs.fred@gmail.com> wrote:
On Monday, December 4, 2023 at 3:25:37?AM UTC-5, John Larkin wrote: >>>>>>>> On Sun, 3 Dec 2023 11:29:51 -0800 (PST), Fred Bloggs
<bloggs.fred...@gmail.com> wrote:
On Friday, December 1, 2023 at 1:07:41?PM UTC-5, Cursitor Doom wrote: >>>>>>>> >> Gentlemen,Waveguides are dispersive, so distort wideband signals. Worse than >>>>>>>> microstrip or multimode fiber.
Can some kind soul define what is meant by "moding" in terms of >>>>>>>> >> microwave propagation - and is it a phenomenon not encountered at >>>>>>>> >> lower RF frequencies?
Thanks,
CD.
Cadence has this explanation on the subject, which was obviously slapped together by some idiot AI program. Generally
speaking mode refers to how the E and M fields of the wave are oriented with respect to the direction of propagation.
This type of
thing only occurs when the physical dimensions of the transmission medium become comparable to the wavelength of the
wave. And
several different modes can exist, to greater and lesser degree, on the guided line simultaneously. Frequency
dependent
phasing of
any intelligence being transmitted by the wave can be seriously affected by the mode(s), degrading its linearity, and
that is
usually not a good thing.
https://resources.system-analysis.cadence.com/blog/msa2021-modes-of-wave-propagation-along-transmission-lines
That's another reason to use an oscilloscope, with a coaxial cable >>>>>>>> connector, to look at wideband signals. A waveguide is a highpass >>>>>>>> filter, an ugly one, and coax (or microstrip, or fiber) is a lowpass >>>>>>>> filter, a pretty good one.
Wherever there's loss, there's dispersion. You're not going to have much loss on short lengths of line on pcb's or
probes,
so
not much dispersion.
Singlemode fiber is astounding. There are a lot of optical wavelengths >>>>>>>> in 100 km.
Going back a few years, a lot of microwave to electro-optical converters became available with high performance
linearity,
70dB, and of course ultra-low loss compared to wires or waveguide at the frequencies they were pushing around.
We recently did a project, a time-domain optical modulator using >>>>>>custom dual-stage lithium niobate modulators and expensive distributed >>>>>>amplifiers.
The two legs of this mach-zender interferometer are unequal length. >>>>>>That's OK if the light is very coherent, but it makes for a bad >>>>>>tempco. So we built a gigantic, massive oven for the modulator.
https://www.dropbox.com/s/29ttap9urihhep1/T500_Top_Final.jpg?raw=1
https://www.dropbox.com/s/f6h8tfyq0xkqx1q/Oven_Cables_pub.jpg?raw=1 >>>>>> >>>>>>https://www.dropbox.com/scl/fi/tb9ng8wo4oyz98y7y0gf2/Old_JD2.jpg?rlkey=2umu7cn25crqgj5zagctmc9x7&raw=1
Distributed amps are, like all RF parts, poorly characterized for >>>>>>time-domain use. One has to experiment.
The price of gold has gone up significally / peaked the last few days :-) >>>
Good time to buy!
The war in Gaza may escalate and then gold will be worth a lot.
https://goldprice.org/live-gold-price.html
Zerohedge reports a great deal on the gold market; lot of very
well-informed people contribute. Check it out some time, Jan. >https://www.zerohedge.com/
"Moding" usually means some bad thing has happened because an
undesired mode is active. As in magnetron moding.
john larkin <jl@650pot.com> writes:
"Moding" usually means some bad thing has happened because an
undesired mode is active. As in magnetron moding.
Bell Labs spent decades understanding and {theoretically} perfecting >waveguides.
Their 4 GHz {later 6 & 11 as well} Long Lines network
{1951~1985} had 3000+ sites. They would feed their KS-15676
horns with a series of traps, filters, and combiners to accomplish
there. There was LOTS of copper used in same. Modes are discussed
in the following:
<http://long-lines.net/tech-equip/radio/BLR0363/087.html> ><http://long-lines.net/tech-equip/radio/BSP402421100/p01.html>
But they didn't quit while they were ahead.
They wanted to put in waveguide from NYC to DC, ><http://long-lines.net/documents/WT4ad.html> ><http://long-lines.net/documents/blr1175/blr401.html>
The field test was a fustercluck; I've chatted with one of
the engineers. when it concluded, the project wrote a glowing
report, and WT died a quiet death.
Soon, MCI was busy burying that fiber stuph, and Ma never caught
up.
On Sat, 16 Dec 2023 17:13:38 -0000 (UTC), David Lesher
<wb8foz@panix.com> wrote:
john larkin <jl@650pot.com> writes:
"Moding" usually means some bad thing has happened because an
undesired mode is active. As in magnetron moding.
Bell Labs spent decades understanding and {theoretically} perfecting
waveguides.
Their 4 GHz {later 6 & 11 as well} Long Lines network
{1951~1985} had 3000+ sites. They would feed their KS-15676
horns with a series of traps, filters, and combiners to accomplish
there. There was LOTS of copper used in same. Modes are discussed
in the following:
<http://long-lines.net/tech-equip/radio/BLR0363/087.html>
<http://long-lines.net/tech-equip/radio/BSP402421100/p01.html>
But they didn't quit while they were ahead.
They wanted to put in waveguide from NYC to DC,
<http://long-lines.net/documents/WT4ad.html>
<http://long-lines.net/documents/blr1175/blr401.html>
The field test was a fustercluck; I've chatted with one of
the engineers. when it concluded, the project wrote a glowing
report, and WT died a quiet death.
Soon, MCI was busy burying that fiber stuph, and Ma never caught
up.
Bell also tried an optical waveguide, a pipe filled with gas that used thermal gradients to continually focus the light.
On 12/16/23 19:49, John Larkin wrote:
On Sat, 16 Dec 2023 17:13:38 -0000 (UTC), David Lesher
<wb8foz@panix.com> wrote:
john larkin <jl@650pot.com> writes:
"Moding" usually means some bad thing has happened because an
undesired mode is active. As in magnetron moding.
Bell Labs spent decades understanding and {theoretically} perfecting
waveguides.
Their 4 GHz {later 6 & 11 as well} Long Lines network
{1951~1985} had 3000+ sites. They would feed their KS-15676
horns with a series of traps, filters, and combiners to accomplish
there. There was LOTS of copper used in same. Modes are discussed
in the following:
<http://long-lines.net/tech-equip/radio/BLR0363/087.html>
<http://long-lines.net/tech-equip/radio/BSP402421100/p01.html>
But they didn't quit while they were ahead.
They wanted to put in waveguide from NYC to DC,
<http://long-lines.net/documents/WT4ad.html>
<http://long-lines.net/documents/blr1175/blr401.html>
The field test was a fustercluck; I've chatted with one of
the engineers. when it concluded, the project wrote a glowing
report, and WT died a quiet death.
Soon, MCI was busy burying that fiber stuph, and Ma never caught
up.
Bell also tried an optical waveguide, a pipe filled with gas that used
thermal gradients to continually focus the light.
It's pretty incredible that optical fibers can be made as transparent
as they are. A few dB/km, utterly amazing.
Jeroen Belleman
On Sun, 03 Dec 2023 08:28:19 -0800, John Larkin <jjlarkin@highlandtechnology.com> wrote:
But waveguides aren't useful for transporting wideband, DC-coupled,
time-domain signals, which is what we do.
Waveguides are quite good high-pass filters. Some even use them as
part of EMP protection. A 2 m high and 1 m wide and tens of meters
long waveguide can be used as a corridor into a Faraday cage room. It
is simultaneously attenuating LF/MF/HF energy, where most EMP energy
is.
On 12/3/2023 6:56 PM, upsidedown@downunder.com wrote:
On Sun, 03 Dec 2023 08:28:19 -0800, John Larkin
<jjlarkin@highlandtechnology.com> wrote:
But waveguides aren't useful for transporting wideband, DC-coupled,
time-domain signals, which is what we do.
Waveguides are quite good high-pass filters. Some even use them as
part of EMP protection. A 2 m high and 1 m wide and tens of meters
long waveguide can be used as a corridor into a Faraday cage room. It
is simultaneously attenuating LF/MF/HF energy, where most EMP energy
is.
Waveguide highpass (scale model of above):
<https://imgur.com/a/pAUuKS6>
On Sun, 17 Dec 2023 00:10:14 -0500, bitrex <user@example.net> wrote:
On 12/3/2023 6:56 PM, upsidedown@downunder.com wrote:
On Sun, 03 Dec 2023 08:28:19 -0800, John Larkin
<jjlarkin@highlandtechnology.com> wrote:
But waveguides aren't useful for transporting wideband, DC-coupled,
time-domain signals, which is what we do.
Waveguides are quite good high-pass filters. Some even use them as
part of EMP protection. A 2 m high and 1 m wide and tens of meters
long waveguide can be used as a corridor into a Faraday cage room. It
is simultaneously attenuating LF/MF/HF energy, where most EMP energy
is.
Waveguide highpass (scale model of above):
<https://imgur.com/a/pAUuKS6>
The mess to the right is "moding", nasty propagation vs frequency.
On 12/17/2023 10:59 AM, John Larkin wrote:
On Sun, 17 Dec 2023 00:10:14 -0500, bitrex <user@example.net> wrote:
On 12/3/2023 6:56 PM, upsidedown@downunder.com wrote:
On Sun, 03 Dec 2023 08:28:19 -0800, John Larkin
<jjlarkin@highlandtechnology.com> wrote:
But waveguides aren't useful for transporting wideband, DC-coupled,
time-domain signals, which is what we do.
Waveguides are quite good high-pass filters. Some even use them as
part of EMP protection. A 2 m high and 1 m wide and tens of meters
long waveguide can be used as a corridor into a Faraday cage room. It
is simultaneously attenuating LF/MF/HF energy, where most EMP energy
is.
Waveguide highpass (scale model of above):
<https://imgur.com/a/pAUuKS6>
The mess to the right is "moding", nasty propagation vs frequency.
Not sure how much of that is "moding" exactly vs. it just gets
dispersive and/or the relatively inexpensive SMA cal standard used
wasn't a very good reference past a few GHz for wave guides.
On Sat, 09 Dec 2023 07:06:09 GMT, Jan Panteltje <alien@comet.invalid>
wrote:
On a sunny day (Fri, 08 Dec 2023 17:59:01 +0000) it happened Cursitor Doom >> <cd@notformail.com> wrote in <79m6nids8r273stl9od79bvk18g67b5gfq@4ax.com>: >>> On Mon, 04 Dec 2023 21:34:51 -0800, John Larkin <jl@997PotHill.com>
wrote:
On Tue, 05 Dec 2023 05:12:47 GMT, Jan Panteltje <alien@comet.invalid>
wrote:
On a sunny day (Mon, 04 Dec 2023 10:05:33 -0800) it happened John Larkin >>>>> <jjlarkin@highlandtechnology.com> wrote in
<fhvrmipbb5diqs3na1gdoedirgnrbinf53@4ax.com>:
On Mon, 4 Dec 2023 06:42:02 -0800 (PST), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:
On Monday, December 4, 2023 at 3:25:37?AM UTC-5, John Larkin wrote: >>>>>>>> On Sun, 3 Dec 2023 11:29:51 -0800 (PST), Fred Bloggs
<bloggs.fred...@gmail.com> wrote:
On Friday, December 1, 2023 at 1:07:41?PM UTC-5, Cursitor Doom wrote:
The war in Gaza may escalate and then gold will be worth a lot.
https://goldprice.org/live-gold-price.html
Zerohedge reports a great deal on the gold market; lot of very
well-informed people contribute. Check it out some time, Jan.
On 9/12/2023 10:39 pm, Cursitor Doom wrote:
On Sat, 09 Dec 2023 07:06:09 GMT, Jan Panteltje <alien@comet.invalid>
wrote:
On a sunny day (Fri, 08 Dec 2023 17:59:01 +0000) it happened Cursitor Doom >>> <cd@notformail.com> wrote in <79m6nids8r273stl9od79bvk18g67b5gfq@4ax.com>: >>>> On Mon, 04 Dec 2023 21:34:51 -0800, John Larkin <jl@997PotHill.com>
wrote:
On Tue, 05 Dec 2023 05:12:47 GMT, Jan Panteltje <alien@comet.invalid> >>>>> wrote:
On a sunny day (Mon, 04 Dec 2023 10:05:33 -0800) it happened John Larkin >>>>>> <jjlarkin@highlandtechnology.com> wrote in
<fhvrmipbb5diqs3na1gdoedirgnrbinf53@4ax.com>:
On Mon, 4 Dec 2023 06:42:02 -0800 (PST), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:
On Monday, December 4, 2023 at 3:25:37?AM UTC-5, John Larkin wrote: >>>>>>>>> On Sun, 3 Dec 2023 11:29:51 -0800 (PST), Fred Bloggs
<bloggs.fred...@gmail.com> wrote:
On Friday, December 1, 2023 at 1:07:41?PM UTC-5, Cursitor Doom wrote:
<snip>
The war in Gaza may escalate and then gold will be worth a lot.
https://goldprice.org/live-gold-price.html
Zerohedge reports a great deal on the gold market; lot of very
well-informed people contribute. Check it out some time, Jan.
Don't. Zerohedge is exactly the kind of publication that would take
money to help a pump-and-dump scheme defraud gullible punters.
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