# Advanced Metamaterial-Integrated Dipole Array Antenna for Enhanced Gain in 5G Millimeter-Wave Bands
## 5 Conclusions  
In this article, a high-gain millimeter-wave antenna with wideband characteristics is presented for 5G NR applications. The high-gain characteristic of the proposed metamaterial-integrated antenna is achieved by using the developed metamaterial structure. Initially, a non-uniform array dipole antenna is designed with a wide operating frequency band on an 8 mil thick Rogers RO4003C substrate. At this stage, the designed dipole antenna offers a peak gain of 8.02 dBi and a wide operating frequency. Afterwards, to boost the gain of the designed antenna, a metamaterial structure is proposed. The unit of the metamaterial structure is created and optimized in CST 2023 simulation software for a targeted frequency band from 22 GHz to 45 GHz. While the unit cell shows a promising performance for the targeted band, a repeated structure of the designed metamaterial unit cell is integrated with the designed dipole array in the direction of radiation. The proposed \(5\times 7\) metamaterial structure enhances the directivity of the antenna's radiation, resulting in a high gain of more than 3 dBi compared to the dipole alone, which means that the gain of the initial antenna is doubled by using the proposed metamaterial. To validate the proposed method, a prototype of the presented antenna is fabricated and measured. The proposed antenna offers a wide operating bandwidth (23.1 GHz-44.8 GHz), covering the whole spectrum of 5G NR technology, including the n257, n258, n259, n260, and n261 bands. Moreover, the antenna offers a high antenna gain of 11.21 dBi with end-fire radiation characteristics. The proposed antenna offers a good radiation efficiency of more than 64% within the functional frequency band. Additionally, the proposed antenna shows a side-lobe level of less than \(-6\) dB within the operating frequency band, which makes the proposed antenna suitable for the MIMO configuration in 5G technology. The overall performance of the presented metamaterial-integrated antenna makes it a viable option for 5G NR millimeter-wave applications.  
Conceptualization, D.C.; methodology, D.C., J.L., and M.A.S.; formal analysis, D.C., W.A.A., and J.L.; investigation, N.K., J.L., M.A.S., and Y.C.; data curation, D.C., Y.C., and W.A.A.; writing--original draft preparation, D.C.; writing--review and editing, M.A.S., W.A.A., and N.K.; visualization, D.C., Y.C., and J.L.; supervision, N.K.; project administration, N.K.; funding acquisition, N.K. All authors have read and agreed to the published version of the manuscript. This work was supported by an Institute of Information & Communications Technology Planning & Evaluation (IITP) grant funded by the Korean government (MSIT) (No. 2022-0-01031, Development of measured EMF big data analysis and management platform). Not applicable. Not applicable. Not applicable. Not applicable. Not applicable. Data Availability Statement: The original contributions presented in this study are included in the article; further inquiries can be directed to the corresponding author. The authors declare no conflicts of interest.