Smart antennas have received increasing interest for mitigating interference in the multiple-input-multiple-output (MIMO) wireless local area network (WLAN). In this paper, a dual-band dual-polarized compact bowtie dipole antenna array is proposed to support anti-interference MIMO WLAN applications. In the antenna array, there are 12 antennas, six for horizontal polarization and six for vertical polarization. In order to achieve dual linear polarizations and beam switching, six horizontal antennas are placed in a sequential, rotating arrangement on a horizontal substrate panel with an equal inclination angle of 60 to form a symmetrical structure, while the other six antennas for vertical polarization are inserted through slots made on the horizontal substrate panel. Furthermore, six pairs of meandered slits are introduced to reduce the mutual coupling between horizontal antennas in the lower band. A prototype of the array with a dimension of 150 150 60 mm is manufactured and exhibits the characteristics of high isolation, good front-to-back ratio, and average gains of 4.5 and 5 dBi over the 2.4-and 5-GHz band, respectively. The MIMO performance of the array is analyzed and evaluated by mutual coupling, the total active reflection coefficient (TARC) and the envelope correlation coefficient. The anti-interference capability of the array is also investigated by the experiment.

Hafnium content and its change are of significance in geochemistry and cosmochemistry; however, the determination of hafnium has always been problematic in analytical chemistry. In this paper, a new idea is proposed for the determination of hafnium in geochemical samples, including rocks, soils, and stream sediments. Through the comparison of two conventional open-type acid digestion methods (HF-HNO3-HClO4 and HF-HNO3-H2SO4), it was found that although neither of these methods could fully digest the zirconium and hafnium in a sample, the zirconium and hafnium digestion behaviors in one sample were consistent in the 60 experimental geochemical reference materials with different properties, so the experimentally determined Zr/Hf ratio in solution could be used to calculate the hafnium content in a sample. In addition, possible mass spectral interferences during the determination of zirconium and hafnium by high resolution inductively coupled plasma mass spectrometry (HR-ICPMS) were studied, and it was found that the mass spectral interferences of the selected isotopes (90)Zr and (178)Hf could be neglected. The mass spectral behaviors of (90)Zr and (178)Hf were also very consistent during the determination by HR-ICPMS. Since the hafnium content was calculated using the ratio value, all of the errors (including the errors in weighing process, the accidental errors during operation and the instrument fluctuation in the determination) of the Zr/Hf ratio could be effectively reduced or even eliminated. The relative standard deviation of the actual samples was lower than 3.2%, and the detection limit of the method (considering the dilution effect and matrix effect during measurement of the Zr/Hf ratio and zirconium content) was 0.04 μg/g. The proposed method could satisfy the requirement for the determination of hafnium in geochemical samples.

Grounded vias modeling is used to analyze the impact on the high speed PCB EMC and SI issues in three aspects, including theoretical analysis, simulator modeling and practical PCB test. In this paper, we discuss the full-wave complex scattering parameter model and full-wave model. Then the full-wave analysis model of the through holes for model validation and comparison are established, by using numerical simulation software HFSS and CST Microwave Studio. The initial test results on the practical PCB show that the analyzed method is reasonable and accurate. And optimized design parameters can ensure the continuity of the impedance of vias, and introduce lesser return loss and insertion loss. It is shown that the signal transmission performance is greatly improved with the grounded via added, which is helpful in specifying the manufacturing tolerance of via designs.

The development of fault detection and diagnosis system is accomplished with the application of PXI interface technology, modular instrument and signal processing technology. The total technical scheme of host computer, portable test platform, signal adapter unit, test interface and cable together with peripheral components is introduced in the presented system. Consequently, the hardware includes master computer (fault test and diagnosis platform), PXI-bus data acquisition system, signal interface adapter, power supply system, interface unit, connection cable and peripheral dedicated test equipments. And the software is developed by C and LabWindows/CVI based on Win32 operating system. In addition, the modular and object-oriented programming are adopted in the software development. The software consists of three parts: the master program running on test and diagnosis platform, the client software module on signal adapter unit as well as the remote interface software module. It can implement fault detection of electrical system on replaceable circuit board and block of the hydraulic system or electrical system. So it can help equipment repairmen and operator perform quick repairs and maintenance to the electrical system for engineering equipment.

A hybrid method, combining analytic Kirchhoff approximation (KA) and numerical method of moment (MoM), is developed to solve the 2D scattering problem of a dielectric target with arbitrary cross section above a moderate perfect electric conductor (PEC) rough surface under TM-polarized tapered wave incidence. Consider the target as the MoM region and the rough surface as the KA region, the induced current on the rough surface is obtained through the KA method, which depends on the incident tapered wave and the field illuminating by current distribution on the target, leaving only unknowns on the target region. In order to reduce the computational costs further, the rough surface is truncated to speed up computation of the scattering contribution from the rough surface to the target. Compared with the conventional MoM, the hybrid method is very efficient to solve the composite scattering problem of target above rough surface, especially for long underlying rough surface. Simulation results validate the effectiveness and accuracy of the hybrid method.