SMARTER STRATEGIES

Metamaterials Meld Multiple Modes onto Single Antenna

R. Colin Johnson | Date: 02-25-10 | Comments

One of the world's first mobile phones to use metamaterials--LG's BL-40--allows multiple radio modes to share a single smart antenna. Invented by Rayspan, now a single antenna can meld today's 3G, GMS, WiFi, Bluetooth and GPS with tomorrow's 4G WiMax and LTE standards.

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.