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A crystal-clear way forward for mmWave 5G


By Ahmed Akgiray, CTO, ALCAN Systems

Chris Pearson, president of 5G Americas – the organisation that facilitates the advancement and transformation of LTE, 5G and beyond – recently said: “Globally, 5G remains the fastest-growing generation of wireless cellular technology ever, even as the world is gripped with a pandemic.”

Although undoubtedly true, there are challenges with the current rollout of 5G. The majority of 5G connections to date use low-band frequencies that are only 20% faster than existing 4G networks. This is an improvement for consumers looking for faster downloads or media streaming, but when it comes to delivering on the 4th industrial revolution that is promised, it simply isn’t enough.

A vital part of the future of 5G is the mmWave technology. This year we have seen mmWave 5G trials demonstrate speeds up to eight times faster than 4G and a lot closer to the industry’s 5G vision. Still, there is still a big question mark over mmWave 5G delivery.


Looking at this from both a technical and commercial perspective, there are three big problems when it comes to 5G using mmWave frequencies.

First is signal penetration. MmWave signals are easily blocked, by buildings, weather, even a user’s hand, making it largely unsuitable for particularly dense urban areas, where there are the greatest number of potential uses.

Then, there’s the mmWave technology’s limited range of around 300 meters – a staggering 50 times less than 4G. This requires significantly more equipment for consistently reliable coverage.

And, finally, with a growing number of equipment comes the need for significantly higher infrastructure investment. The implications of this are compounded as mmWave must use advanced technologies such as beam-steering for effective coverage which come with a much higher price tag. To solve these problems, operators will have to embrace innovation and new approaches. One of the most promising solutions is using liquid crystal as the core component of much 5G equipment. That is the same liquid crystal found in smartphones and TV screens, which when used in different ways has the potential to solve some of the biggest mmWave 5G challenges.

Smart antennas with liquid crystals

Based on research from the Technical University of Darmstadt, the liquid crystal technology has been used to build phased array smart antennas. These can take the form of relay antennas, customer premises equipment (CPE), or even integrated into vehicles to realise the connected cars vision.

Using this technology as the core material of the phased array enables the beam steering that is essential for mmWave 5G at a fraction of the cost. These smart antennas combine liquid crystal display (LCD) technology with microwave LCs and array antenna design. Unlike most beam-steering options on the market, this is a totally passive design that has several key benefits when it comes to cost reduction. The materials are cost-effective and can be mass produced, reducing the CAPEX. In addition, being a passive solution it uses very low power, reducing the ongoing OPEX costs of the solution.

Beyond the solving of problems for 5G, liquid crystal smart antennas offer benefits for future solutions, too. Most technologies supporting 5G are being stretched to their physical limitations to work at mmWave frequencies; yet, a liquid crystal technology improves the performance of Electronically Steering Antennas (ESAs) at higher frequencies. This also makes it a perfectly viable solution for supporting 6G and beyond.

A clear solution

This core technology can take a number of forms, and it also offers an additional, unique advantage when used in CPE. With mmWave 5G blocked by buildings, to successfully deliver any form of indoor coverage requires equipment, which can be both expensive and unsightly.

Using liquid crystals allows designers to make their equipment less visible, not because of the slim form factor it allows, but because it is transparent. It can be held together with glass – also transparent, and have the metal/conductive elements of the antenna printed in a way that cannot be seen by the human eye. The result is a transparent antenna with a high level of functionality yet at low cost.

The possibilities for transparent smart antennas are endless, and open 5G doors not thought possible with current technologies. These antennas could be integrated into windows to deliver reliable, consistent 5G in-building, hugely expanding the possibilities of what can be achieved with 5G.

Beyond this, there is an opportunity to install this technology to enable connected cars. Transparent antennas can be integrated into sunroofs and car windows, and, given that mmWave works in similar frequency bands to satellite, means it could be used to develop hybrid satellite/5G antennas to provide robust coverage in the absence of a 5G signal. Even consumer devices can benefit from the integration of a transparent smart antenna into their screens. Given the display is typically visible at all times, it can navigate the challenge of signal being blocked by a user’s hand.

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