Evolution and innovation of antenna systems for beyond 5G and 6G

With the advance of the 5 generation (5G) wireless communication system in recent years, 5G network construction and terminal equipment have gradually been finalized and entered the commercial stage. The 6 generation (6G) mobile communication system has become a promising and important area with both academic and industrial concerns. Compared with 5G, 6G will achieve higher access rate (10–100 times higher), lower access delay, as well as wider and deeper communication coverage, with much better energy and spectrum efficiency. It enables the material, process, technology, and forms of antenna and radio frequency (RF) systems to evolve continuously. There are several important tendencies in the development of antenna and RF systems. 1. Transform of antenna to new frequency bands In a 5G mobile communication system, millimeter-wave (mm-Wave) band is an indispensable part. The Internet of Space (IoS), which is one of the possible evolution directions of 6G, also needs a variety of antenna systems that work in Ka and other bands to achieve wider coverage at all times and locations. In recent years, terahertz (THz) with much higher frequency has attracted wide attention from both academia and industry. It is one of the most advanced technologies recognized internationally. 2. Breakthroughs in the performance of antennas with new materials and metamaterials New materials and metamaterials with unique features that are difficult to obtain naturally will enable antennas to be much smaller, more immune to interferences, and much better in performances. New materials and metamaterials could break the barriers for antenna theory and engineering, which were impossible with traditional materials. 3. Evolution of antenna propagation channel New propagation characteristics are generated by antennas with a new configuration or by antennas in new frequency bands, such as three-dimensional multiple input multiple output (MIMO) antennas and mm-Wave/THz antennas. It is inevitable that antenna designers and engineers nowadays need to consider antenna performance in the presence of different channel characteristics in different scenarios and applications. 4. Significant changes in antenna-related measurement technology In the 5G era, traditional measurement methods, indicators, and even concepts may no longer be applicable to the new 5G over the air (OTA). Brand new measurement methods and measurement indicators are being rapidly prototyped and submitted to meet international standards. At this time, it is of great importance to comprehensively make plans for 5G and 6G antenna measurement technologies. To sum up, the antenna system for future communications is facing numerous challenges. The improvement of antenna system performance will inevitably lead to improvement of the overall performance of wireless communication systems. The evolution and innovation of antenna configurations can also pave the way for new applications. In this context, the Chinese Academy of Engineering (CAE) organized a special issue on evolution and innovation of antenna systems for beyond 5G and 6G in Frontiers of Information Technology & Electronic Engineering. This special issue covers antennas, passive and active devices and systems, Frontiers of Information Technology & Electronic Engineering www.jzus. zju.edu. cn; engineering.cae. cn; www.springerlink. com ISSN 2095-9184 (print); ISSN 2095-9230 (online) E-mail: jzus@zju.edu. cn