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A novel S-band antenna is proposed in this paper. The antenna consists of two layers of radiant dipole. The unit is capable of realizing broad beam-width of 144° in E-plane with isolation better than -35dB between two ports. The circular polarization can be achieved by exciting two ports with equal amplitude and 90° phase difference. Moreover, the axial ratio is less than 2dB in the antenna operating frequency band. At last, a triangular grid array with 64 elements is designed. The simulated results show that the designed array can meet the requirements of large scanning angle. It can be applied for the fifth generation mobile communications (5G) Multiple-Input Multiple-Output (MIMO)base station.

In order to investigate the enhanced control and operation of wind power generation systems based on doubly-fed induction generators (DFIG) when grid voltage is unbalanced, a novel phase-locked loop system used to realize real time phase synchronization is presented. With the help of the novel PLL, the phase of positive sequence component can be obtained quickly and accurately, even if the grid voltage appears to be unbalanced and distorted. As a result, the rapidity and stability of PLL are greatly improved. The simulation and experiment results have verified the validity and effectiveness of it under the unbalanced and distorted grid voltage.

A wholly aromatic polypyrene was synthesized by direct chemical oxidative polymerization of pyrene with ferric chloride as oxidant in hexane/nitromethane. Successful synthesis of polypyrene was thoroughly confirmed by IR, UV/Vis, 1D (1)H NMR, 2D (1)H-(1)H COSY, 2D (1)H-(13)C HSQC, MALDI-TOF MS, elemental analysis, and X-ray diffraction methods. The results indicated that the polypyrene was formed mainly through dehydro coupling between 2- or 1- and 2'- or 1'-positions on pyrene rings having a degree of polymerization of around 24. The polypyrene was purified and then separated into THF-soluble (ca. 10 %) and THF-insoluble (ca. 90 %) fractions. Compared with insulating pyrene monomer, the polypyrene is a controllably conducting polymer that has low conductivity of 3.4x10(-8) S cm(-1) in its virgin state, moderate conductivity of 2.28x10(-4) S cm(-1) upon iodine doping, but much higher conductivity of up to 81.2 S cm(-1) after the insoluble polypyrene was heated up to 1300 degrees C in nitrogen with a high char yield of 70.6 %. In particular, the soluble polypyrene demonstrates much stronger visible color fluorescence and much lower toxicity than pyrene. The soluble polypyrene would be advantageous for detecting Fe(3+) with almost no interference of other metal ions. The soluble and insoluble polypyrene fractions have potential applications as intrinsically luminescent and highly conducting carbon materials, respectively.