Reconstructing the antenna design solution for mobile devices in the 5G era

Latest update time：2022-01-12

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Antennas are used to transmit and receive radio waves, connect to the RF front end, are the starting point of the receiving channel and the end point of the transmitting channel, and are the most important component of mobile devices. With the advent of the 5G era, the RF path of 5G mobile phones is usually more than twice that of LTE mobile phones. At the same time, insufficient space limits the ability to add new antennas and/or share antennas between multiple frequency bands, which leads to more complex problems. Therefore, the next generation of mobile devices faces major engineering challenges in antenna design.

How do you address these challenges? And how do you solve tricky RF issues? Let’s take a closer look.

With the RF paths more than doubling, and given the limits on the total number of antennas achievable in a fixed form factor, the logical way to handle the growth in the number of RF paths is to increase the bandwidth of each antenna to support more frequency bands.

However, this approach also presents challenges. Antennas with wider bandwidths tend to have higher losses. They may require more space, as the size of the antenna is determined by the lowest frequency it supports.

Additionally, using a single antenna to transmit and receive multiple frequency bands simultaneously increases the risk of mixed signals creating non-linear spurious emissions.

Solving these problems is not easy: careful analysis and specialized antenna design techniques are required, combined with appropriate filtering and routing solutions in the RFFE.

To address the ultra-wideband issue , manufacturers could look for ways to group some of these antennas together to reduce the overall space required. Another consideration is whether to put an antenna in the bezel of the phone to achieve excellent omnidirectional ranging performance.

The key issue with carrier aggregation and EN-DC is that low-low aggregation may require the use of a third antenna that supports low-band transmission. This means that manufacturers need to find more space in the phone to place this antenna and ensure that the selected antenna position can provide adequate performance under all usage conditions.

For the higher Tx power issue, this also means that all post-PA components within the RFFE, including the antenna tuner, need to handle more power. This typically means using larger components, which becomes an issue given space constraints. The increase in output power also means that the RFFE components will generate higher levels of spurious signals, requiring additional attention to mitigate desense and RSE issues.

New designs allow for less space for antennas. New phone designs with foldable and rollable screens present a host of antenna challenges. Careful design and positioning of antennas are required to ensure efficient operation under all usage conditions.

The next generation of mobile devices presents a considerable number of antenna design and engineering problems. So who will be the first to solve the challenges? In addition to the well-deserved pride that comes with overcoming an extremely difficult challenge, the team that wins the innovation race will have a significant competitive advantage in the battle for consumer support.

The above content is excerpted from "Reimagining Antenna Design Solutions for Next-Generation Mobile Devices". If you want to know more details, please click to read the original text and start learning.

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