Metamaterials to revolutionise wireless infrastructure -

With the increasing proliferation of wireless devices inside and out of the home and workplace there are concerns over how interference from the external electromagnetic environment can cause problems for the connectivity of devices in the future.

According to Dr Andrew Treen of the University of Exeter and Qinetic, a defence technology and security firm, we are seeing more wireless devices and tags that are symptomatic of the massive wireless infrastructure which has the potential to cause interference, which people are often totally unaware of. 

Treen gives the example of many people carrying radio frequency identification (RFID) tags around on their person without knowing.

“People often have four of five RFID tags on them at any one time, including a key fob for a car, an oyster card or a swipe card for work,” Treen tells TechEye. “There have even been companies which have placed them inside shoes to ensure that separate components match during production. Essentially this shows just how widespread wireless technology currently is in the world.”

While the tags will not cause disruption themselves - it is devices used to receive data such as a security barrier that cause problems - the interiors of homes and offices are likely to have a further range of wireless devices that can disrupt signals. 

This may include light switches, printers and even microwave ovens, all of which can have an effect on the electromagnetic environment and can lead to reduced signal when in operation.

There is also the problem of external electromagnetic signals causing interference from one building to another which can be the cause of unknown disruption to, for example, broadband connectivity.  Treen cited an example of someone using a video sender to extend a TV signal.

“A colleague’s relative would find that whenever she used her video sender it would mean that she was unable to use any other wireless or Bluetooth connection. While she just became used to the notion of not being able to use the internet at certain times, it is unlikely her neighbours would have appreciated this unknown lapse in signal,” Treen told TechEye.

Indeed it is a common problem that an internet connection can suddenly disappear for no clear reason, and Treen believes that broadband providers may unfairly get the blame when the real culprit could be a neighbour using an item such as a microwave, a problem that would be exacerbated in, say, a block of flats where you may be close to a large number of other people all using disruptive appliances at certain times.

While being unable to watch BBC iPlayer for half an hour during the evening may not be a massive problem to a lot of users, in a business environment wireless connectivity can prove to be crucial, and an immediate, high-speed connection is only likely to become more vital in the future for both business and personal uses. 

The main reason for such poor connectivity is, according to Treen, due to inadequate building management of wireless connectivity.  

There are many materials used in the design of buildings which can cause interference to external blocking of a wireless signal – this can range from the foil coating on thermal insulation to rain dampening the outside of a concrete building. 

Furthermore regulations for glass installation – which can often constitute a whole building’s façade – are now insistent on reflectivity of infrared signals, “meaning that wireless signals are potentially bounced back as well”.

Treen believes action needs to be taken in order to ensure that buildings in the future can enable the correct management of wireless signals. The way this can be done is through the correct implementation of electromagnetic materials; absorbers, reflectors, scatterers and filters which can all contribute to the improved operation of wireless systems.

Treen cites the use of metamaterials that can for example allow a wireless signal into a building while stopping other signals from getting out. While absorbing or relective materials would traditionally take up considerable space, the use of metamaterials can offer a method of improving management of an electromagnetic environment with a material that can be just two millimetres thick. 

In the past, absorbers would be in the region of three inches thick, the current availability of metamaterials means that it could be almost as easy to implement such technology as it would to apply wallpaper to a wall.

Metamaterials technology has a wide range of uses, for example it is similar technology to that which has been heralded as offering ‘invisibility cloaking’, and in this instance the metamaterial can be artificially engineered to give specifically designated functions.  For example a metamaterial can use a material such as copper to be combined with another material and arranged in a specific pattern that offers unique results, like the ability to reflect certain frequencies while allowing others to pass through.

“The absorber materials can be made using polyester films with thin surface metallisation, for example aluminium, one side of which is patterned, hence the common reference to ‘crisp packet’ technology,” explained Treen.

To actually implement such technology is not as difficult as it might sound.  In fact Treen believes that metamaterials can be incorporated by adapting existing materials to decrease the amount of work required, although new builds should be designed with wireless connectivity in mind.  

“We aim to use modified building materials where possible as this reduces the risk for the architects with regards to building insurance and warrantee issues, and increases the familiarity of the construction teams.  This means that the metamaterials are easier to install,” said Treen.

“Using this approach we are normally talking about one or two more processes, patterning and lamination, being applied to the materials.  So it will be more expensive, though not massively so. A wallpaper type approach is the likely first step.”

With worries about wireless technology usage, such as mobile phones, causing adverse health effects like brain tumours it's possible people could be concerned about what Dr Treen calls  “invisible pollution” in our homes. 

Although there is arguably no basis to such theories, as Treen himself says, and TechEye is loathe to subscribe to hysteria over brain-frying, there is certainly a proportion of the population who have voiced concerns about being exposed to such an environment on a regular basis.

But whether your reasons for wishing to prevent unwanted signals from permeating the walls of your office or home are due to health reasons or just for the well-being of wireless connections, ensuring there are measures to prevent signal disruption are key for the future of a wireless infrastructure.