Today's multimode mobile phones and other devices, from
netbooks to wireless modems to GPS
navigators, require complex multielement antennas that need expensive
radio-frequency (RF) switches and complicated matching networks when utilizing
different communications bands and protocols. But by harnessing the
metamaterials recently made famous for their experimental applications as
invisibility cloaks, Rayspan (San Jose, Calif.)
can now build a single antenna for all communications signals.
LG recently revealed it is using Rayspan’s metamaterial
antenna for its BL-40 mobile phone.
Earlier this month, the National Institute of Standards and
Technology (NIST) showed a metamaterial antenna design that was 50
times smaller than the traditional RF solution. Now Raypan has stepped
forward to reveal that metamaterials can also be used to design multimode
antennas that receive RF signals in different bands. The first customer to
reveal it is using a Rayspan metamaterial antenna in a commercial device is LG
for its BL-40 handset, which handles GSM, EDGE, HSDPA, WiFi, Bluetooth, GPS
and FM.
Metamaterials were originally conceived by professor John
Pendry at Imperial College
(London), when he imagined
designing a composite material that behaved in the opposite manner of
conventional materials. For instance, light always bends in the same direction
when traveling through glass—it always has a positive index-of-refraction.
Consequently, lenses cannot correct for some aberrations. However, by designing
metamaterials that bend light in the opposite way from normal—i.e., with a
negative index-of-refraction—and integrating the new metamaterial with normal
materials, light could be bent whichever way is necessary.
Metamaterials were first constructed in laboratory
experiments by Pendry's associates, Duke
University scientists David Schurig
and David Smith, for the microwave frequency bands used for communications. The
researchers popularized metamaterials by demonstrating how combining normal materials
and metamaterials using both positive and negative indices of refraction could
redirect microwaves around objects, essentially creating the scientific
foundation for the invisibility cloak in the Harry Potter series fantasy novels
written by British author J.K. Rowling.
Rayspan has now demonstrated that the same principles that
Pendry, Schurig and Smith demonstrated for invisibility cloaks, and that NIST
used to shrink its antenna by 50-fold, could also be used to create a single
antenna that is tuned to multiple bands, thereby eliminating the need for the
complex and expensive RF switching and matching networks that occupy much of
the space inside a mobile phone today.
Rayspan works with original equipment manufacturers (OEMs)
of mobile phones, netbooks, wireless routers and wireless modems to integrate
super-small, multiband metamaterial antennas into particular mobile devices.
The multimode metamaterial antenna is integrated right onto the existing
circuit board of the mobile device.
