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?

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?

Fiction.

Efficient antennas can be made which are much shorter than a half
wavelength. They'll be narrowband and highly reactive, however. What do
the scientists say about the bandwidth and feedpoint impedance? Where
can we find published data?

Sounds to me like somebody is trying to sell some stock.

Roy Lewallen, W7EL

Here is the journal article:

R.W. Ziolkowski, P. Jin, J.A. Nielsen, M.H. Tanielian and C.L.
Holloway. Design and experimental verification of Z antennas at UHF
frequencies. IEEE Antennas Wireless Propag. Lett., 2009 vol. 8, pp.
1329-1332.

Elektor magazine had a news report on these antennas.

"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.

In their latest prototype device,* the research team used a metal wire
antenna printed on a small square of copper measuring less than 65
millimeters on a side. The antenna is wired to a signal source.
Mounted on the back of the square is a “Z element” that acts as a
metamaterial — a Z-shaped strip of copper with an inductor (a device
that stores energy magnetically) in the center (see photo).

“The purpose of an antenna is to launch energy into free space,”
explains NIST engineer Christopher Holloway, “But the problem with
antennas that are very small compared to the wavelength is that most
of the signal just gets reflected back to the source. 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. Even more
intriguing, Holloway says, “these metamaterials are much more
‘frequency agile.’ It’s possible we could tune them to work at any
frequency we want, on the fly,” to a degree not possible with
conventional designs.

The Z antennas were designed at the University of Arizona and
fabricated and partially measured at Boeing Research & Technology. The
power efficiency measurements were carried out at NIST laboratories in
Boulder, Colo. The ongoing research is sponsored by the Defense
Advanced Research Projects Agency.

* R.W. Ziolkowski, P. Jin, J.A. Nielsen, M.H. Tanielian and C.L.
Holloway. Design and experimental verification of Z antennas at UHF
frequencies. IEEE Antennas Wireless Propag. Lett., 2009 vol. 8, pp.
1329-1332.

NIST has an article on these antennas and a photo of a prototype.

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

In article
,
Roger wrote:

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

Fact or Fiction?

Roger-

I'd say this was factual fiction!

Perhaps they are receive-only antennas that use something like an MOS
FET to drive a low impedance cable.

Perhaps the one-fiftieth wavelength antennas were used in the
experiments that failed!

Fred
K4DII

On Jan 29, 5:14*pm, Roy Lewallen wrote:
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?

Fiction.

Efficient antennas can be made which are much shorter than a half
wavelength. They'll be narrowband and highly reactive, however. What do
the scientists say about the bandwidth and feedpoint impedance? Where
can we find published data?

Sounds to me like somebody is trying to sell some stock.

Roy Lewallen, W7EL

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

On Fri, 29 Jan 2010 21:24:47 -0800 (PST), Roger
wrote:

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

Not much original work there - It had been kicking around for years
prior to publication. Boeing Skunk Works stuff I posted here at least
10 years ago when it was more interestingly portrayed as negative
refraction elements.

A number of other papers on these antennas are located he

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

a bibliography.... So what?

73's
Richard Clark, KB7QHC

On Fri, 29 Jan 2010 17:57:08 -0800 (PST), Roger
wrote:

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

In fact, commercial Ham antennas with similar efficiencies at similar
scales have been around for decades.

Shrinking them further encounters loss accumulating at the 4th power
of size. This is a very difficult proposition to beat in stale
reporting with the concurrent lack of proven models following after
lo' these 4 years. That is pretty sound evidence of these researchers
having been lost beyond the precipice of an astronomical plunge in
efficiency.

73's
Richard Clark, KB7QHC

On Fri, 29 Jan 2010 18:02:03 -0800 (PST), Roger
wrote:

NIST has an article on these antennas and a photo of a prototype.

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

Yeah, yeah, yeah. Now, for the true test of comprehension, answer
this:
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)

If this cannot be sensibly answered from the accumulation of you
reading of all links and bibliographies offered, then not much is
being offered up in the way of discussion.

73's
Richard Clark, KB7QHC