The deformation behaviors of a droplet on surface of composite insulator can strengthen local electric field, which could finally lead to flashover. Both experiments and numerical simulations for dynamic behaviors of a droplet on the surface of a composite insulator under applied AC voltage are investigated in this paper. Experiments are performed to study the influences of water droplet’s volume and conductivity on the dynamic behaviors. Two critical parameters are proposed to describe the morphological change process of water droplet, and it is shown that the process can be divided into three stages. Moreover, these motion laws are explained by establishing theoretical factors and physical influence models. In addition, we perform computer simulation to study the dynamic behaviors of a water droplet under AC field, and the findings are in good consistency with our experimental results, proving the rationality of the theoretical physical model. It is found that the vibration frequency of droplet changes regularly with at different stages under the AC electric field.
This paper presents a dual-band eight-element multiple-input multiple-output (MIMO) antenna for 5G applications. The 8-element antenna is formed into two 4×4 MIMO systems that operate at 2500-2600 MHz and 1800-2200 MHz bands. The antenna elements are mounted along the perimeter of a rectangular ground plane with a total size of 110 × 80 mm2 and are printed on both sides of a low-profile PCB material. Elements radiate through open rectangular slots etched on the antenna's ground conductor. The open slots are excited by T-shaped microstrip lines fed by 50-Ω coaxial connectors. The size of the ground plane's slots, and the T-shaped radiators control the resonance of the antenna's elements. The proposed design employs orthogonal elements to mitigate mutual coupling. The isolation between ports is less than -10 dB. The radiation efficiency ranges from 40% to 65% across operating frequency bands.