Roger wrote:

Roy,

Here is a paper describing the feedpoint impedance and how they
counteract the capacitive reactance without the typical matching
network.

http://www.ece.arizona.edu/~ziolkows..._July_2006.pdf

A number of other papers on these antennas are located he

http://www.ece.arizona.edu/~ziolkows...0Antennas.html

I look forward to your feedback and the comments by others on this
subject,

Roger

Thanks very much for the additional information. It's very good news
indeed, and the first I've heard of anyone being able to do this. My
so-far 100% reliable antenna rule of "Small-Broadband-Efficient: Choose
Any Two" might finally be broken. My "fiction" judgment was based on the
initial description which sounded so much like so many I've heard over
the years. I amend it to "Sure looks promising", since it looks like
they've finally really attacked one of the fundamental limitations in a
way that might bear fruit. A career in electronic equipment product
development has taught me that there's a vast distance between getting
something to work once in a lab and building them by the thousands out
of real parts and having them all work as specified. The path between is
full of surprises and obstacles, most of which can be overcome but
sometimes some which simply can't. I sure hope this can be developed to
the point of practicality. An encouraging factor is that there's a real
market for efficient, electrically small antennas in things like RFID
tags and keychain remote control units, to name just a couple. This
means that money will be available for development.

Roy Lewallen, W7EL

On Fri, 29 Jan 2010 17:05:26 -0800 (PST), Roger
wrote:

The experimental antennas are as small as one-
fiftieth of a wavelength and could shrink further.

Only one frequency is reported:
F1. 300 MHz
and two standards of measure are reported:
L1. The square is 30 millimeters on a side.
L2. square of copper measuring less than 65 millimeters on a side.

Obviously not one antenna being described here. Further reading
(courtesy of googling for deeper, less frivolous reporting than puff
piece press releases) reveals another frequency:
F2. 570 MHz

There is a curious and loosely correlated ratio between
F1/L2 and F2/L1.

Next, we consider that there is more to the radiator than the
"metamaterial" - a quite remarkably large and thick disk of solid
copper that appears to be serving the traditional function of
counterpoise.

Barring that last observation, taking the 300 MHz (suggested
excitation) and the stated 65mm physical description that attends this
frequency; and accumulating the meander's length; then that is a 260mm
long monopole (meandering, albeit), with an inductor as center load.

The 300 MHz wavelength is (naturally) 1000mm. A resonant monopole is
typically 250mm.

Several questions come to mind:
1. What is the extra 10mm for?
2. What is the extra inductor for?
3. What is the copper disk (looks to be 1/4 wave in radius) for?
4. What happened to the 1/50th wavelength claim?
5. What virtue of "metamaterial" adds efficiency to what would
ordinarily be 100% efficient with that much copper shown?
6. Who gives a ****?

73's
Richard Clark, KB7QHC

On Jan 29, 7:57*pm, Roger wrote:
The metamaterial
makes the antenna behave as if it were much larger than it really is,
because the antenna structure stores energy and re-radiates it.”
Conventional antenna designs, Holloway says, achieve a similar effect
by adding bulky “matching network” components to boost efficiency, but
the metamaterial system can be made much smaller.

So far nothing has been written about the radiation resistance of this
"1/50-wave" antenna.

Even if the design eliminates the feedpoint Xc of this electrically
small radiator at the operating frequency, its radiation resistance
could be expected to be miniscule, because the Rr of a radiator
depends on the electrical wavelengths it exposes to space.

The claim that it radiates 95% of the power applied to it may be true,
but needs to evaluated with the radiator as part of an r-f system --
where with very low Rr, much of the available power can be subject to
very high losses before it reaches the radiator.

RF

On Jan 30, 5:43*am, Richard Fry wrote:
Even if the design eliminates the feedpoint Xc of this electrically
small radiator at the operating frequency, its radiation resistance
could be expected to be miniscule, because the Rr of a radiator
depends on the electrical wavelengths it exposes to space.

What if a metamaterial conductor were discovered with a natural
VF=0.1? In the lab, light has been slowed down to a crawl.
--
73, Cecil, w5dxp.com

On Fri, 29 Jan 2010 17:05:26 -0800 (PST), Roger
wrote:

NIST engineers are working with scientists from the University of
Arizona (Tucson) and Boeing Research & Technology (Seattle, Wash.) to
design antennas incorporating metamaterials — materials engineered
with novel, often microscopic, structures to produce unusual
properties. The new antennas radiate as much as 95 percent of an input
radio signal and yet defy normal design parameters. Standard antennas
need to be at least half the size of the signal wavelength to operate
efficiently; at 300 MHz, for instance, an antenna would need to be
half a meter long. The experimental antennas are as small as one-
fiftieth of a wavelength and could shrink further.

Fact or Fiction?


Crack your cellphone and look at the antenna there.
Open your Bluetooth dongle.

Then calculate the lamda in air.


So what.
Ever heard about Epsilon?
http://en.wikipedia.org/wiki/Epsilon

w.

Hmmm, I'm thinking it could be useful as an element for a frequency agile
radar array. Diversity radar?
If current radar detection systems rely on the target detecting an incoming
beam at a given pulse rate and frequency, then by varying the frequency and
pulse rate constantly, detection would be more difficult.
Computer hardware and software is sufficiently powerful to be capable of
processing the target returns at varying frequencies and GPS satellites can
provide a frequency locked source for synchronising the transmitter and
receiver, so you end up with effectively a stealth active radar system.
A wide band electrically tuned antenna would be essential for such an
application. It might even be able to detect stealthy aircraft and ships as
they tend to be optimized to absorb/divert frequencies in the most used
radar bands.
An electrically controlled frequency agile antenna which forms part of an
electrically steerable planar system would also be useful for jamming
multiple frequencies and sources. This could turn out to be a somewhat
expensive project.

Mike G0ULI

"Roger" wrote in message
...
NIST has an article on these antennas and a photo of a prototype.

http://www.nist.gov/public_affairs/techbeat/current.htm

On 1/29/2010 10:46 PM, Richard Clark wrote:

...
What is THE metamaterial?
(cut and paste in response is not an answer, in your own words please,
as YOU understand it)

For extra credit:
What IS metamaterial?
(cut and paste in response is not an answer, in your own words please,
as YOU understand it)
...
73's
Richard Clark, KB7QHC

The materials used are very similar, in many cases exact, to the
materials used in TTD's (Temporal Tremor Detectors.)

Regards,
JS

On 1/30/2010 11:24 AM, Helmut Wabnig wrote:

...
Crack your cellphone and look at the antenna there.
Open your Bluetooth dongle.

Then calculate the lamda in air.


So what.
Ever heard about Epsilon?
http://en.wikipedia.org/wiki/Epsilon

w.

Exactly. My Bluetooth Dongle (and in no way representative of my real
dongle--either in size or performance! :-) ) is about the size of my
index finger nail. I'd imagine use of a suitable magnifying glass would
allow me to appraise the antenna it contains ...

Regards,
JS

On 1/29/2010 11:30 PM, Richard Clark wrote:

...
Next, we consider that there is more to the radiator than the
"metamaterial" - a quite remarkably large and thick disk of solid
copper that appears to be serving the traditional function of
counterpoise.
...
73's
Richard Clark, KB7QHC

ABSOLUTELY!

Doubles as a VERY handsome paperweight, don't you agree?

Regards,
JS

"John Smith" wrote in message
...
On 1/30/2010 11:24 AM, Helmut Wabnig wrote:

...
Crack your cellphone and look at the antenna there.
Open your Bluetooth dongle.

Then calculate the lamda in air.


So what.
Ever heard about Epsilon?
http://en.wikipedia.org/wiki/Epsilon

w.

Exactly. My Bluetooth Dongle (and in no way representative of my real
dongle--either in size or performance! :-) ) is about the size of my index
finger nail. I'd imagine use of a suitable magnifying glass would allow
me to appraise the antenna it contains ...

Regards,
JS
-
You would use a magnifying glass to examine an antenna in your dongle?