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A Beam-Steering Antenna for 5G Mobile Phones

For the first time, a beam-steering antenna is integrated into the metal casing of a mobile phone

2 min read
Prototype of mobile device with the proposed phased array antennas.
Photo: Shanghai University/IEEE

The final architecture of 5G cellular networks has yet to be carved in stone. However, it looks as though millimeter waves, with their ability to obtain wider bandwidths, will play an important role in 5G—the next generation of mobile phones. The combination of these bands along withdirectional phased-array antennas, in which radio waves can be steered electronically in a desired direction, will constitute one of the key technologies in future 5G cellular systems.

While there have been a number of research efforts that have demonstrated that these phased-array antennas can be added into mobile phones using low-cost substrate boards, no one had demonstrated that it’s possible to build these antennas into phones with full metallic casings, as can be found in the high-end mobile devices from numerous manufacturers.

Now researchers from the Shanghai Institute for Advanced Communication and Data Science at Shanghai University in China have developed a 28 Gigahertz (GHz) beam-steering antenna array that can be integrated into the metallic casing of 5G mobile phones.

“The antenna elements and arrays are easily integrated on the metallic frame or casing of a mobile phone, which is more suitable for industry mobile phone design,” said Danny Yu, the lead author of the research in the journal IEEE Transactions on Antennas and Propagation. “Compared to all other existing works for mm-Wave 28 GHz band, this work is totally unique in such a sense that it is very close to what the industry is working towards at the moment.”

The antenna elements and arrays proposed by Yu and his colleagues are connected and controlled by a radio frequency integrated circuit (RFIC) transceiver. In this arrangement, the phase and amplitude of each element is controlled by the RFIC transceiver to achieve beam-steering characteristics.

For practical purposes, another benefit of the design is that the beam-steering arrays are placed on the left and right edges of the mobile phone. This takes into account the effect that a user’s hand placement has on beam steering performance.

In this paper, Yu and his colleagues set out how the antennas and RFIC transceiver can be integrated into metallic casings. But Yu acknowledges that beam-steering topologies and algorithms will also have to be developed specifically to meet the stringent requirements of mobile phones.

While Yu emphasizes that this technology provides ease of integration, low fabrication cost, and can fit into the restricted size specifications of today’s mobile phones, there are some issues that still need to be addressed.

For example, Yu points out that the design of the structures that carry the radio signal from the antenna to the RFIC transceiver would need to be further refined in order to scale up for mass production. Also, commercial manufacturing processes would need higher machining precision in order to produce components that could meet mm-wave band requirements.

In continuing research, Yu and his colleagues are testing the over-the-air performance of their prototype in handling information sent by millimeter waves.

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Metamaterials Could Solve One of 6G’s Big Problems

There’s plenty of bandwidth available if we use reconfigurable intelligent surfaces

12 min read
An illustration depicting cellphone users at street level in a city, with wireless signals reaching them via reflecting surfaces.

Ground level in a typical urban canyon, shielded by tall buildings, will be inaccessible to some 6G frequencies. Deft placement of reconfigurable intelligent surfaces [yellow] will enable the signals to pervade these areas.

Chris Philpot

For all the tumultuous revolution in wireless technology over the past several decades, there have been a couple of constants. One is the overcrowding of radio bands, and the other is the move to escape that congestion by exploiting higher and higher frequencies. And today, as engineers roll out 5G and plan for 6G wireless, they find themselves at a crossroads: After years of designing superefficient transmitters and receivers, and of compensating for the signal losses at the end points of a radio channel, they’re beginning to realize that they are approaching the practical limits of transmitter and receiver efficiency. From now on, to get high performance as we go to higher frequencies, we will need to engineer the wireless channel itself. But how can we possibly engineer and control a wireless environment, which is determined by a host of factors, many of them random and therefore unpredictable?

Perhaps the most promising solution, right now, is to use reconfigurable intelligent surfaces. These are planar structures typically ranging in size from about 100 square centimeters to about 5 square meters or more, depending on the frequency and other factors. These surfaces use advanced substances called metamaterials to reflect and refract electromagnetic waves. Thin two-dimensional metamaterials, known as metasurfaces, can be designed to sense the local electromagnetic environment and tune the wave’s key properties, such as its amplitude, phase, and polarization, as the wave is reflected or refracted by the surface. So as the waves fall on such a surface, it can alter the incident waves’ direction so as to strengthen the channel. In fact, these metasurfaces can be programmed to make these changes dynamically, reconfiguring the signal in real time in response to changes in the wireless channel. Think of reconfigurable intelligent surfaces as the next evolution of the repeater concept.

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