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Remarkably Small Antennas - Fact or Fiction
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? |
#2
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Remarkably Small Antennas - 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 |
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Remarkably Small Antennas - Fact or Fiction
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 |
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Remarkably Small Antennas - Fact or Fiction
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 |
#5
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Remarkably Small Antennas - Fact or Fiction
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 |
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Remarkably Small Antennas - Fact or Fiction
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. |
#7
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Remarkably Small Antennas - Fact or Fiction
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. |
#8
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Remarkably Small Antennas - Fact or Fiction
NIST has an article on these antennas and a photo of a prototype.
http://www.nist.gov/public_affairs/techbeat/current.htm |
#9
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Remarkably Small Antennas - Fact or Fiction
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 |
#10
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Remarkably Small Antennas - Fact or Fiction
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 |
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