[Digital Daily Correspondent Kang So-hyeon] A technology to overcome the limitations of the ultra-high frequency (mmWave) band with strong straightness is emerging. After this technology is commercialized, it is expected that 5G mobile communication (5G) coverage will be greatly improved. LG U+ announced on the 15th that it would verify the technology of ��Reconfigurable Intelligent Surface (RIS)��, a core antenna technology for 5G and 6G. RIS is a technology that adjusts the path so that radio waves can reach the receiver over obstacles by using the electromagnetic reflection characteristics of the antenna surface. For example, by attaching a transparent film-type antenna to a coated glass window that is difficult for radio waves to pass through, it bends the direction of radio waves to reach the inside of the building. Currently, there are technical limitations to commercialize 28GHz band 5G. This is because, in the case of a high-frequency band such as 28 GHz, the diffraction (bending or passing property) of radio waves is weak, so it has a disadvantage in that it cannot avoid or pass through an obstacle when it encounters an obstacle. The coverage is also only 10~15% compared to the 3.5GHz band, but there was no technology to compensate for this shortcoming. Among them, RIS is attracting attention as a technology to improve coverage for shaded areas. NTT DoCoMo, a Japanese mobile operator, already announced a plan to improve indoor coverage using RIS last year. NTT DoCoMo said that. RIS is similar to a repeater in that it aims to reach radio waves in the shaded area. However, RIS is expected to be cheaper to manufacture compared to repeaters. The problem with the existing repeaters was the price. This is because the higher the frequency band, the more semiconductor chips are used in manufacturing, limiting the cost reduction. On the other hand, RIS can be manufactured at a lower price by replacing the role of the semiconductor chip controlling the communication signal in the repeater with a reflective material. If tens or hundreds of semiconductor chips are used in the repeater, it is known that only 1 or 2 are used in the case of RIS. However, it is expected that RIS cannot completely replace repeaters as it simply reflects radio waves. The repeater amplifies the received signal and retransmits it, but RIS only eliminates the shadow area and cannot amplify the weakened signal. An official from the telecommunication industry said, “From the point of view of operators, they have no choice but to look at how much profit is compared to the cost of constructing communication infrastructure.” “The higher the frequency band, the higher the investment cost. appears to be,�� he said. ��The challenge for the industry in the future is how cheaply it can be made to make an antenna surface that acts as a reflector,�� he added.