Friday, May 2025
01:30 PM - 01:50 PM
Room: LL21AB
Session: mmWave Systems Integration and Advanced Chiplet Packaging on Glass
Progress in Development of Reconfigurable Intelligent Surfaces with Liquid-Crystal and Glass Substrates for RF Applications
Description:
To overcome drawbacks of mmWave and upper-mid carrier frequency for 5G/6G wireless communications, one of the alternative solutions, reconfigurable intelligent surfaces (RIS), is the talk of the town. A main purpose of RIS is to maintain line-of-sight status through a new propagation path. To realize this function in real time, a tunable element is required. By utilizing the change in characteristics according to voltage variation, liquid crystal (LC) materials can be used as the tunable element in the electromagnetic domain. The LC materials are used to push the envelope barring reduction of complexity, manufacturing cost and loss from incumbent semiconductor based active devices. To verify and reveal the merits of our LC based RIS, several stages of research and development (R&D) activities were carried out. This paper addresses our step-by-step approach to developing advanced active RIS, thinner and larger RIS. Our first proof-of-concept sample started with a 200 ?m-thick cell gap and size of 100×100 mm2, and then we now we have a 20 ?m-thick for the cell gap and size of Gen2 glass (The first sample is 100×100 mm2 with a 200 ?m cell gap, the second sample is 100×100 mm2 with a 100 ?m cell gap, the third sample is 150×150 mm2 with a 20 ?m cell gap, and the current sample is 357×423 mm2 with a 20 ?m cell gap). From the first to the present sample, we can reduce a response time dramatically (tens of second to several milliseconds) with innovative design changes and optimizations as the cell gap has reduced from 200 to 20 ?m. Furthermore, we have several benefits of the increased size, such as wide and fine beam steering angle, small spillover losses, high directivity, etc. These advantages and further details about the measured performance, our experiences, and perspectives through the evolutionary journey to development of RIS will be presented and discussed in the conference.