A 2-Bit Pancharatnam-Berry Coding Metasurface For Ultra-Wideband And Polarization-Insensitive RCS Reduction

Because Pancharatnam-Berry (PB) geometrical phase can only be generated in the co-polarized reflection coefficient under circular polarized (CP) incidence for a reflective metasurface, designing a reflective PB coding metasurface must be based on an appropriate polarization conversion metasurface (PCM), which can realize CP-maintaining reflection. In this work, to design a reflective 2-dit PB coding metasurface for radar cross section (RCS) reduction, an ultra-wideband PCM is proposed at first, the simulated results show that the PCM can realize ultra-wideband CP-maintaining reflection from 8.6 to 35.9 GHz; moreover, PB phase will be generated in its co-polarized reflection coefficient by rotating its unit structure. Thus based on the PCM, an ultra-wideband reflective 2-dit PB coding metasurface is constructed successfully. The simulation and experiment results show that the coding metasurface has excellent performance in RCS reduction under arbitrary polarized incidences, compared with a pure metallic plate with the same size, its RCS can be reduced more than 10dB in the frequency band 8.2-35.2GHz with a relative bandwidth of 124.4%.

3D Metallic Plate Lens Antenna based Beamspace Channel Estimation Technique for 5G Mmwave Massive MIMO Systems

Beamspace channel estimation mechanism for massive MIMO (multiple input multiple output) antenna system presents a major process to compensate the 5G spectrum challenges caused by the proliferation of information from mobile devices. However, this estimation is required to ensure the perfect channel state information (CSI) for lower amount of Radio Frequency (RF) chains for each beam. In addition, phase shifter (PS) components used in this estimation need high power to select the beam in the desired direction. To overcome these limitations, in this work, we propose Regular Scanning Support Detection (RSSD) based channel estimation mechanism. Moreover, we utilise a 3D lens antenna array having metallic plate and a switch in our model which compensates the limitation of phase shifters. Simulation results show that the proposed RSSD based channel estimation surpasses traditional technique and SD based channel estimation even in lower SNR area which is highly desirable in the millimeter wave (mmWave) massive MIMO systems.

Metallic plate heating by a flat burner: Experiments and CFD simulations

Metal plate heating by new microflare burner has been studied experimentally and by CFD simulations, additionally, concentrations of NOx were measured to compare conventional and microflare burners. In addition, the article provides a numerical simulation of the combustion of a microflame burner. It has been demonstrated that microflare burners are more efficient and allows more uniform heating of metal plates. The comparison of NOx concentrations of conventional and microflare burners indicate better performance of the latter.

Comparison of passive damping treatments based on constrained viscoelastic layers and multi-resonant piezoelectric networks.

This work aims at comparing the damping performances of two passive damping treatments based on piezoelectric or viscoelastic patches. The motivation for such a comparison stems from the fact that the two damping techniques have been developed fairly independently, and are rarely compared. First, the dynamic response of a simply-supported metallic plate is measured experimentally after being equipped with constrained viscoelastic patches or piezoelectric patches connected to an electrical network. In order to extend the comparison, a numerical model of the structure is set up and validated to evaluate the damping performances of both passive treatments under different configurations (for instance equal-mass and equal-thickness configurations). Finally, with regard to these experimental and numerical results, the advantages and the limitations in using viscoelastic or piezoelectric treatments are discussed.