Microstructures and phase compositions of as-cast and extruded ZK60-xBi (x = 0–1.64) alloys were investigated. Meanwhile, the tensile mechanical property and hardness were tested. With increasing the Bi content, the as-cast microstructure is first refined obviously, and then becomes coarse slightly. New small block compound which is rich in Zr, Zn, Bi and poor in Mg increases gradually, and MgZn2 phase decreases gradually. The second phase mainly precipitates along the grain boundary. The as-cast tensile mechanical property is first enhanced obviously, where the tensile strength σb, yield strength σ0.2 and elongation δ can reach 265 MPa, 151 MPa and 13.5% for ZK60-0.23Bi alloy, respectively, then remains the high value for ZK60-(0.37–1.09)Bi alloys, and finally decreases obviously for ZK60-1.64Bi alloy. After hot extrusion, the obvious dynamic recrystallization occurs. Broken block compound distributes along the extrusion direction by zonal shape. The average grain size can reach only 4–6 μm. The extruded tensile mechanical property is enhanced significantly, where σb, σ0.2 and δ are at the range of 345–360 MPa, 285–300 MPa and 15.5–19.5%, respectively. Extruded tensile fracture exhibits a typical character of ductile fracture

In this paper, a novel ultra-wide band (UWB) random 3-bit coding metasurface with polarization independence has been designed to realize radar cross-section (RCS) reduction. The proposed structure consists of polarization conversion metasurfaces (PCMs), which possess the capability of rotating linear polarization waves to their orthogonal ones in an UWB. The polarization-independent property can be attributed to the random rotation angle of each constituting unit. Due to the randomness of 3-bit coding and rotation angle of each element, the divergence of the reflected beam is greatly improved. In addition, the effect of RCS reduction with respect to the unit period length and the unit position are also discussed. Finally, a prototype is fabricated and measured to validate the simulation. The experimental results demonstrate that an ultra-wide band RCS reduction over 10 dB, ranging from 18.3–42.2 GHz, can be attained by the proposed coding metasurface and the maximum reduction is 28.7 dB.

For a wideband radiated signal, the probability density function (PDF) of the received total power in a reverberation chamber (RC) is no longer an exponential distribution. It is shown in this letter that the PDF of the received total power approaches to a normal distribution when the bandwidth of the signal increases. Measurements are performed and the results are validated.

Statistical analysis for material shielding effectiveness (SE) measurement in a nested reverberation chamber (RC) and a contiguous RC is given in this article. By using Mellin transform and the associated statistical methods, the corresponding analytical expressions of the SE are derived, respectively, for the sample material under test with good and poor electromagnetic shielding performance. Moreover, the probability density function, the expected value, and the standard deviation of SE in different scenarios using nested and contiguous RCs are obtained analytically. Monte Carlo simulation and measurements in nested and contiguous RCs are performed to verify the analytical expressions.

In this letter, a fast energy-based method of antenna efficiency measurement in a reverberation chamber (RC) in time domain (TD) is proposed. The antenna efficiency is determined by comparing the received energy from the antenna under test with that from the reference antenna. The measurement results are compared with that from the conventional reference antenna method in the frequency domain (FD). The proposed method needs no mechanical stirring or only a few mechanical stirrer positions, which could reduce the measurement time significantly.