Why Transparent Antennas are Critical to JCAS in Mobile Devices?
Each generation of wireless communication has brought transformative changes to our daily lives and the design of mobile devices. With 6G on the horizon, one of its most promising features—Joint Communication and Sensing (JCAS)—aims to merge wireless connectivity with high-precision sensing. Today, most JCAS research focuses on base stations, where large antenna arrays enable advanced MIMO (multiple-input multiple-output) systems for fast communication and precise sensing. However, implementing JCAS in compact devices like smartphones or smartwatches remains challenging. Their current edge-antenna designs lack the space and array size needed for such complex tasks. This limitation could be overcome by a breakthrough: Transparent Antennas. Unlike conventional metal antennas, transparent antennas can be seamlessly embedded into the device’s screen, allowing both light and radio waves to pass through without interference. This innovation opens up new possibilities—making it feasible to integrate large antenna arrays directly into the display without affecting design or usability.
The Power of Transparent Antennas
Transparent antennas are emerging as a promising solution to meet the growing demand for compact, high-performance, and visually unobtrusive antenna integration in modern electronic devices. By leveraging transparent conductive materials such as indium tin oxide (ITO), graphene, and silver nanowires, these antennas offer sufficient electrical performance without compromising display clarity or device aesthetics. Fig.1 shows a prototype developed by CHASM, and Fig.2 illustrates some of the potential application scenarios.
Figure. 1 Prototype from CHASM
Figure.2 Possible applications
Key Advantages of Transparent Antennas:
- Idea for High-Frequency Band: Transparent antennas can efficiently support millimeter-wave (mmWave) frequencies used in 5G and 6G. These high frequencies allow for smaller antenna designs, making them perfect for transparent materials.
- Space-Saving and Visually Appealing: Unlike traditional metal antennas, transparent antennas can be embedded in screens, glass, or surfaces—making them invisible and preserving the sleek design of modern devices like smartphones, AR glasses, and cars.
- Flexible Placement for Better Coverage: Because they are invisible, transparent antennas can be installed in many new locations—on windows, walls, or even displays—enabling better network coverage and more flexible deployment in cell-free networks.
- Supports Compact MIMO Designs: Transparent antennas make it easier to integrate multiple antennas into a small device without cluttering the design—ideal for advanced wireless systems like Massive MIMO used in 5G/6G.
But There’s a Catch: Blockage Problem
A unique challenge with mobile devices is their constant physical interaction with human hands. Unlike static infrastructure, smartphones are used while being held—often tightly—by users. This everyday behavior can become a serious performance bottleneck. When the hand comes into contact with areas where antennas are mounted, the signal quality drops significantly, and the problem becomes even more severe at higher frequencies, such as those used in 5G and future 6G networks. To illustrate this, we modeled a smartphone equipped with six edge-mounted antennas, reflecting a common design in current smartphones. Two typical hand-holding styles are considered: 1) Vertical holding (portrait mode, Type I blockage) and 2) Horizontal holding (landscape mode, Type II blockage). Each hand grip causes different blockage areas. In additional, we compare two transmission strategies: 1) Uniform transmission, where all antennas are used equally and 2) Antenna selection, where only the best antenna is selected for use. We simulate the system under a fixed 3-meter distance between the smartphone and the access point. Fig. 3a presents the achievable rate under 28 GHz operation and Fig. 3b shows the result at 300 GHz. These results clearly highlight how severe antenna blockage can degrade communication performance, particularly as frequency increases-a critical insight for designing next-generation user equipment.
Figure 3. Simulation results
Why This Matters
While edge-mounted antennas are highly susceptible to blockage caused by the user’s hand, integrating transparent antennas directly into the screen offers a promising solution. Since people rarely grip the screen area during normal use, on-screen antennas are less likely to be blocked. However, partial blockage can still occur, and when it does, maintaining reliable communication requires the use of channel hardening techniques.
But there’s more: blockage isn’t just a problem—it can be a feature! The movement of hands and fingers across the screen naturally changes the signal strength and propagation characteristics. By analyzing these variations, the device can achieve sensing capabilities. This enables it to detect, track, and even predict hand or finger movements, unlocking possibilities for advanced interaction features. This opens the door to advanced applications in gesture control, user authentication, and interactive interfaces.
Stay tuned as our ongoing research continues to explore the integration of on-screen transparent antennas, aiming to ensure robust communication even when part of the screen is blocked by the hand, while also enabling hand and finger sensing for future interactive applications in smart devices.
An article by Shun Zhuge.
Further Reading
- https://www.chasmtek.com/transparent-antennas
- Liu, Q. Wang and S. Pollin, “Enhancing Indoor-to-Outdoor mmWave Communication with Transparent Amplifying Intelligent Surface,” ICC 2023 – IEEE International Conference on Communications, Rome, Italy, 2023, pp. 6467-6473, doi: 10.1109/ICC45041.2023.10279668.
- Hong et al., “mmWave 5G NR Cellular Handset Prototype Featuring Optically Invisible Beamforming Antenna-on-Display,” in IEEE Communications Magazine, vol. 58, no. 8, pp. 54-60, August 2020, doi: 10.1109/MCOM.001.2000115.
- Y.-X. Sun, D. Wu, X. S. Fang and J. Ren, “On-Glass Grid Structure and Its Application in Highly-Transparent Antenna for Internet of Vehicles,” in IEEE Transactions on Vehicular Technology, vol. 72, no. 1, pp. 93-101, Jan. 2023, doi: 10.1109/TVT.2022.3205899.