A double‐layered DGS transmission line is proposed with a smaller DGS size and less radiation loss. Changing the air boundary to a dielectric boundary reduces the effective electric length at the DGS aperture area. An equivalent circuit model is introduced to analyze the DGS transmission line and the resonator circuit designs. Due to the increase in the effective dielectric constant, the proposed structure can be realized with less sensitivity to metallic environments. From the experimental results, the proposed double‐layered DGS can achieve a reduction of 90.1% in size and insensitivity at up to 5 mm of separation from the DGS aperture to the metallic plate.
I. INTRODUCTION Since the system requirements for the fifth-generation (5G) mobile communication were released, related research has rapidly accelerated toward implementing core technologies such as millimeter waves, micro cells, massive multiple-input multipleoutput (MIMO), full duplexing, and adaptive beamforming [1, 2]. Although the 3GPP LTE Release 16 is expected to be the final specification of the 5G system to be released at the end of 2019, some leading companies have provided commercial 5G services since early 2019. To achieve high-speed and real-time services, the 5G system adopted a broad bandwidth at a millimeter wave band with high propagation loss. To overcome the demerits, the system is organized with adaptive beamforming and massive MIMO systems. These technologies require a numbers of antenna elements, complicated beamforming networks, and phase control circuits for each channel. For the accurate control of adaptive beams, recent novel approaches have been introduced, including phased arrays in millimeter-waves [3], switchable beamforming networks [4], beamforming on cellphones [5], and digital/hybrid beamforming [6]. In addition, a wideband antenna element is required to cover the ultra-wideband [7, 8], while the agile phase control circuits with high phase resolution should be considered to achieve wideband characteristics [9-11]. Moreover, wideband component design is an important issue regarding the 'sub-6 GHz band' to make the same beam shape for each channel. The only solution adjusting antenna beams for each channel is digital beamforming. Due to their high power-consumption
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.