A team of UPNA researchers attached to the Smart Cities Institute (ISC) have designed several models of highly reliable, compact antennas, capable of emitting more than 100 GHz (gigahertz), which could be used in the future for ultra-high-speed point-to-point communications. These models foresee the deployment of 6G technology -the implementation of which for real applications and sale is expected to come in the next five years-, which will require the technological development of infrastructure, such as high-performance antennas, to make it possible to communicate at greater bandwidths.
From left to right, the researchers Iñigo Ederra, Miguel Beruete, Dayan Pérez-Quintana and Jorge Teniente on the UPNA’s Arrosadia campus
According to Miguel Beruete, Professor of Signal Theory and Communications, member of the Antennas Group and leader of TERALAB, ‘to put it simply, we can say that Wi-Fi works at 2.4 GHz and mobile telephony operates at around 2.1 GHz. But to reach the speeds discussed when referring to a 6G scenario, we have no choice but to try to reach 300 GHz. These bands are still being explored, but are, in fact, already covered in the 5G standard (the 5G standard now reaches 100 GHz).’
Although the 6G standard is yet to be defined and the spectrum bands to be used for data transmission are unknown, there is talk of speeds close to 1 TB with latencies of less than 0.1 ms, which would mean emitting at very high frequencies. For this reason, the team formed by the Antenna Group researchers Miguel Beruete, Iñigo Ederra, Jorge Teniente and Dayan Pérez-Quintana have been working for the last year on advanced antennas capable of operating reliably in frequency bands hitherto barely explored.
The biggest problem equipment designers face when confronted with this challenge is production, because operating at higher frequencies means minimising the size of the elements, which leads to defects. ‘The good thing about electromagnetism is that it's perfectly scalable. If I want to reach very large frequencies, theoretically I just need to make smaller antennas. But greatly reducing the size of the elements results in problems with tolerances,’ Beruete explains.
Due to this paradox, the conventional solutions that modern-day antennas use are not suitable for operating properly at such high frequencies, forcing researchers in the field to devise disruptive innovations. The developments of the UPNA researchers combine a range of improvements described in the scientific literature in a single solution.
Advanced design
The models devised in the last year are based on a highly advanced type of flat antenna design, known as ‘bull's eye’. These antennas have a characteristic helical shape and several concentric grooves around a central point, allowing the radiation to be directed with high precision. ‘Having this shape, the antenna radiates almost everything forwards, like a laser pointer, and does so very powerfully. It might look like a parabolic antenna in practice, but the shape is much more compact, which makes it easy to put in place, embed in a fuselage or whatever’s necessary,’ Beruete points out.
The problem with these models is that it had not been possible to use them to date with high frequencies, something which has now been achieved by incorporating a waveguide system using the ‘Gap Waveguide’ technique. ‘The typical solution for transmitting radiation is usually a waveguide, a kind of metal pipe through which the signal is conducted. The "Gap Waveguide" system confines the radiation inside a kind of metal box with a series of pins or posts which trap the wave and guide it, without losing power, which favours operation at high frequencies,’ the project leader explains.
Another great advantage of this new generation of antennas is the incorporation of a circular polarisation system. Polarisation refers to the orientation of the electric field radiated, which is usually horizontal or vertical in conventional communications. The difficulty lies in the fact that if there are obstacles in the path of the waves (for example, in indoor environments), depolarisation, a phenomenon that implies alteration in the orientation of the field, occurs, leading to a drop in the power of transmission. ‘But circular polarisation means the field goes around in a circle. This option is much more robust against depolarisation, because, despite rebounds, the electromagnetic field continues to go around practically unaltered; it doesn’t change much,’ the professor informs.
In the opinion of the researchers, these new developments, which together make for a compact, robust and very powerful solution, could be used in any point-to-point link thanks to their ability to radiate in a single direction without power losses. ‘It's an excellent solution, for example, for a university that wants to connect two remote areas on a campus with an ultra-high-speed communication network without having to lay down a cable,’ Beruete concludes.