Isto cheira-me a outra historia como a da "antena enterrada"<br><br><div class="gmail_quote">2009/8/31 João Gonçalves Costa <span dir="ltr"><<a href="mailto:joao.a.costa@ctt.pt">joao.a.costa@ctt.pt</a>></span><br>
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<div><font face="Verdana"><img style="width:205px;height:212px" height="267" src="http://www.personadondada.com/wordpress/wp-content/uploads/2008/11/invisibility_cloak.jpg" width="205"></font></div>
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<h1>'Invisibility cloak' antennas</h1>
<p><font face="Verdana">The materials used to make real-life invisibility cloaks
could also make antennas smaller.</font></p>
<p><font face="Verdana"><strong>New Scientist</strong> reports that "an
international team of physicists has now created metamaterials that can be tuned
to a range of different frequencies as required. A cellphone antenna fashioned
from the new material could be tuned to work very efficiently across a small
frequency range, but retuned to a different band for roaming."</font></p>
<p><font face="Verdana">"Because metamaterials can manipulate electromagnetic
waves to a greater degree than normal materials – and even bend light
"backwards" – a small metamaterial antenna is as effective as a much larger
standard antenna at transmitting or receiving waves."</font></p>
<p><font face="Verdana">"But a narrowband metamaterial antenna has its drawbacks –
it's rare that engineers require an antenna tuned to just one frequency, for
instance, different countries have allocated different frequency bands to their
cellphone networks. A tunable metamaterial antenna could allow a wireless gadget
to work "outstandingly well" at the frequencies used in one country, but also
carry the option of retuning for use abroad."</font></p>
<p><font face="Verdana">Read the New Scientist article - <em>'Invisibility cloak'
antennas could shrink cellphones</em> - at<br></font><a href="http://www.newscientist.com/article/dn17660-invisibility-cloak-antennas-could-shrink-cellphones.html" target="_blank"><font face="Verdana">http://www.newscientist.com/article/dn17660-invisibility-<br>
cloak-antennas-could-shrink-cellphones.html</font></a></p>
<p><font face="Verdana">Active invisibility cloaks could work at many
wavelengths<br></font><a href="http://www.embedded.com/219400692?cid=NL_embedded" target="_blank"><font face="Verdana">http://www.embedded.com/219400692?cid=NL_embedded</font></a></p>
<p><font face="Verdana">*<font face="Times New Roman">Um <b>Metamaterial</b> é um
material produzido artificialmente e que é dotado de propriedades que não
existem na natureza.</font></font></p></div>
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<br></blockquote></div><br><br clear="all"><br>-- <br>Best 73 from: regards from: CT4RK Carlos Mourato - Sines - Portugal<br><br> Save the Radio Spectrum! Eliminate Broadband over Power Line. Salve o espectro electromagnético!. Não use a rede electrica para transmitir dados. Os "homeplugs power line" e a tecnologia "power line" causa fortes interferencias noutro serviços sem voce se aperceber. Diga não à tecnologia power line. Proteja o ambiente<br>
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