The exploration of new synthesis methods is important for the improvement of the thermoelectric property of a material for the different mechanisms of microstructure fabrication, surface activity modulation, and particle refinement. Herein, we prepared p-Bi2Te3 bulk materials by a simple synthesis method of the plasma-assisted ball milling, which yielded finer nanopowders, higher texture of in-plane direction, and higher efficiency compared to the traditional ball milling, favoring the simultaneous improvement of electrical and thermal properties. When combined with the Te liquid sintering, nano-/microscale hierarchical pores were fabricated and the carrier mobility was also increased, which together resulted in the low lattice thermal conductivity of 0.52 W·m–1·K–1 and the high power factor of 43.4 μW·cm–1·K–2 at 300 K, as well as the ranking ahead zT of 1.4@375 K. Thus, this work demonstrated the advantages of plasma-assisted ball milling in highly efficient synthesis of p-type Bi2Te3 with promising thermoelectric performance, which can also be utilized to prepare other thermoelectric materials.

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In this article, a radiation pattern reconfigurable antenna (RPR antenna) based on the complementary source principle is proposed for automobile communication. This antenna achieves four end-fire radiation patterns in four directions by controlling the operating states of PIN-diodes. The structure of this center-fed antenna includes a corners-shorted patch and four parasitic monopoles with eight PIN-diodes to control the states of monopole antennas. The monopole antenna works as an electric current source while the center-fed patch antenna can be equivalent to in-phase magnetic currents at its periphery due to the existence of the loaded monopole. Then the radiation mechanism of the RPR antenna can be explained as a pair of orthogonal magnetic and electric current sources. As a result, four end-fire radiation patterns can be obtained by changing OFF/ON states of PIN-diodes and this antenna can be applied for high-resolution omnidirectional coverage by switching among four modes. To verify the simulation, an example antenna is fabricated and measured. The measured result exhibits a À10-dB impedance band of 3.21-3.73 GHz with a maximum realized gain of 7.07 dBi.Results show that this antenna is suitable for automobile 5G communication.

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