FYI,

I have been in communication with Mr. Vincent. There are two pieces of info
which I have acquired which I find intriguing:

1) Mr. Vincent states that testing is now occuring at a facility that is well
known for viable, independent testing (not a ham facility) (I am familiar with
the facility);

2) Mr. Vincent will be giving a talk at the August Boxboro NE Hamfest.

I applaude him for these two efforts and am looking forward to seeing his
results.

73,
Chip N1IR

Another press write-up:

http://www.planetanalog.com/news/sho...cleID=21402311


Jim, K7JEB

Another press write-up:

http://www.planetanalog.com/news/sho...cleID=21402311


Jim, K7JEB


Where is says:
"With my technique, I reduce the inductive loading that is normally required to
resonate the antenna by as much as 75 percent . . . by utilizing the
distributed capacitance around the antenna," he explained.

"I looked at all the different approaches used to make antennas smaller, and
there seemed to be good and bad aspects" to each, Vincent said. "A helix
antenna is normally known to be a core radiator, because the current profile
drops off rapidly; they are just an inductor, and inductance does not like to
see changes in current, so it's going to buck that.

"What I found was that for any smaller antenna, if you place a load coil in the
middle you can normalize and make the current through the helix unity; that is,
you can maximize it and linearize it," he added.


Let me guess, he "snaked" the part of the radiator in the plane, rather than
winding it as a coil, then added loading coil and and perhaps
capacitive/inductive top hat (like Force 12 uses and old Ukrainian patent)

Cecil, have you noticed the statement about the loading coil current? Buck
that!


Yuri, K3BU.us

Here's some info about Rob Vincent:
http://www.phys.uri.edu/people/rob.html

Al WA4GKQ

Where is says:
"With my technique, I reduce the inductive loading that is normally required
to
resonate the antenna by as much as 75 percent . . . by utilizing the
distributed capacitance around the antenna," he explained.


To linearize the current you need to place capacitance at the top.

His design-as stated in the press release --calls for about 0.4 waves
electrical length as a helix (0.008 inches x 100 turns @ 1 Ghz). This is
electrically long for a 1/4 monopole configuration. So the design is
electrically long but very physically short: Stated 15 inches high for 15
meters. (This means that if you don't slow the wave, there is more than one
current max.) This will drive the feedpoint impedance up and improve bandwidth.
It also increases ohmic loss. Thus the tradeoff.

A loading coil on the helix will help linearize it--I'm there so far.
Distributing the capacitance is trickier.

In fairness, we don't know the design, but there is nothing new that appears to
me--in my opinion--in these stated approache(s).

The press releases claim high efficiency and broad bandwidth.Of course, these
are relative terms. 1/15 wave high monopoles with excess of 10% BW with gains
of -1.5 dBd are prior art. If you make a bit taller then it becomes much more
interesting.

BUT we don't live in a single band world anymore. In fact, we don't live very
much in a monopole world anymo the trend is ground independent, wideband
antennas, or at least multiband ones..

There's a lot more to antenna issues: anyone who thinks the issue with RFID
antennas is gain and size doesn't understand the issues with RFID, for
example. Right, Wayne:-)?

Losses are a huge concern in very compact designs--placing them on substrates
loads them intractably, for example.

Also, knowledge of the prior art is essential for making a claim of
'revolutionary' antenna technology. I have not seen anything in the press
releases that --in my opinion--indicates a good knowledge of the prior art by
the inventor. He may have it, but it is not apparent from these statements. He
obviously has a good working knowledge of the problem. That's not the same
thing.

Anyway, fun stuff. The bottom line on what appears--to me-- as the claim
relevant to hams: If you need a -1 to -2 dBd short monopole that covers the CW
portion of 40M, for example, this may be useful, in my opinion. If you want to
stick it on your roof then be prepared to have a big roof:-).

73,
Chip N1IR

"Yuri Blanarovich" wrote in message
...
Another press write-up:
http://www.planetanalog.com/news/sho...cleID=21402311
Jim, K7JEB

[snip] "A helix
antenna is normally known to be a core radiator, because the current
profile
drops off rapidly; they are just an inductor, and inductance does not like
to
see changes in current, so it's going to buck that.

This sounds like false theory. He is implying that a distributed
inductor opposes a difference in current along its length, no?

The RF current in the distributed inductor can be different along its
length, modeling shows that, but this is AC and it is _always_ opposing the
changing AC (in this case RF) current at any point of the coil. That's what
inductors do. I can't get this to extend to opposing different AC currents
along the length of a long coil. If there is enough field from one end of
the coil coupling to the other end, then a falling field at the first end
tends to oppose a change in the current at that end as well as at the other,
but that's an opposition to a change in instantenous current, which will
increase inductance, not the AC current magnitude...


"What I found was that for any smaller antenna, if you place a
load coil in the middle you can normalize and make the current
through the helix unity; that is, you can maximize it and
linearize it," he added.

I can't get "Linearize" to work. Does he mean, "vary linearly along the
length"? "Normalize" and "unity" are pretty obsure as well.

Guess I'll wait for the movie to comeout.

--
Steve N, K,9;d, c. i My email has no u's.

This sounds like false theory. He is implying that a distributed
inductor opposes a difference in current along its length, no?

The RF current in the distributed inductor can be different along its
length, modeling shows that, but this is AC and it is _always_ opposing the
changing AC (in this case RF) current at any point of the coil. That's what
inductors do. I can't get this to extend to opposing different AC currents
along the length of a long coil. If there is enough field from one end of
the coil coupling to the other end, then a falling field at the first end
tends to oppose a change in the current at that end as well as at the other,
but that's an opposition to a change in instantenous current, which will
increase inductance, not the AC current magnitude...


"What I found was that for any smaller antenna, if you place a
load coil in the middle you can normalize and make the current
through the helix unity; that is, you can maximize it and
linearize it," he added.

I can't get "Linearize" to work. Does he mean, "vary linearly along the
length"? "Normalize" and "unity" are pretty obsure as well.


He means that a very electrically small monopole can be designed so it has no
current maximum: the current does not vary in magnitude with height. The
current value is the same along it's length.This is common for top hat
monopoles which are less than 1/30 wave in height.

The issue arises in the Vincent discussion because the electrical length of the
antenna is far in excess of the height, so the current changes--unless you
distribute additional inductance and capacitively truncate at the top.

Because the antenna is electrically long and physically short, it has a higher
feedpoint resistance, although the tradeoff of higher ohmic losses to higher
rad resistance gives, at best, a wash on gain.
It is, in effect, a short, slow wave antenna.

Monopole limits: At 1/30 wave height, the bandwidth can be on order of a few
percent or less, with -2 dBd or so. I have worked with such antennas for some
time. If you increase heights to 1/15 wave, the increase in bandwidth can be
dramatic.

The problem is that broadcast antennae need reduced height--but don't need the
many-percent bandwidth. They also have arcing issues from high voltage.

The problem is that commercial and military applications (such as cell
phones) need multiband or wideband--and not the modest bandwidth.

The problem is that RFID doesn't have a size and gain problem, but an impedance
problem.

Thus the 'revolution' is somewhat small in population....But hams need modest
bandwidth and low height. Hence a potential niche.--if you have room for a
ground plane.

Is there really a market for short , single band, ham monopoles? Understand
that for a few more feet in height, you can get an MFJ multiband
vertical--without a radial system.

73,
Chip N1IR

How do you put capacitors in? Is this a good slow wave solution?

CCD antenna use capacitors in a distributed way to cancel the inductance. They
are commonly used in 1 wave dipole configurations. They have higher feedpoint
impedances than 1/2 wave dipoles and they have 3 dB gain when fully stretched.
Their pattern is figure 8, like a 1/2 wave dipole.

The Vincent antenna could use such an arrangement to emulate a 1/2 wave
monopole CCD (that is, a 1 wave dipole) where the 1/2 wave electrical length is
wound into a helix along the height.. In any case, there are a number of ways
of doing this. In my opinion, this is not new, if that is the case.

I suspect that Vincent has a number of combinations of arrangements, depending
on the desired height above 1/30 waves.

Remember: these are not efficient antennas; they are slow wave antennas. Put
lots of power into them and they will heat up; arc; and melt. They trade gain
against efficiency. They are not multi or wideband.

I would be very interested to know how hot a Vincent antennas when running 1500
watts continuous for an hour....If it's hot it's not efficient.

73,
Chip N1IR.