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A novel printed antenna having a frequency band-notched function for UWB applications is proposed and studied. With a pair of inverted C-shaped slots introduced around the microstrip line on the ground, a frequency-notched response at 5.2 GHz is obtained. The designed antenna satisfies the VSWR requirement of less than 2.0 in the frequency band between 2.8 and 10.7 GHz while showing the band rejection performance in the frequency band from 4.8 to 5.7 GHz. Good monopole-like radiation patterns and antenna gains have also been obtained. [ABSTRACT FROM AUTHOR]

A new welding method called 'keyhole mode variable polarity plasma arc weld bonding' (keyhole mode VPPAWB) was presented to join Mg alloy. It was put forward as a hybrid of the keyhole mode variable polarity plasma arc welding (keyhole mode VPPAW) and the adhesive bonding process. The characteristic of the keyhole mode VPPAWB technique was discussed. After welding, the microstructures and mechanical properties of joint were investigated. The results showed that a lap joint without pores and inclusions could be obtained by the keyhole mode VPPAWB process. Keyhole mode and variable polarity power were helpful to obtain a free defect joint. The fusion zone of joint consisted of refined isometric crystal, and the grain was finer in the upper fusion zone than that in the bottom. Compared with keyhole mode VPPAW joint and adhesive bonding joint, the keyhole mode VPPAWB joint exhibited a better failure load. [ABSTRACT FROM AUTHOR]

Two-dimensional isothermal airflows in a 1/4-scale ventilated model room were numerically investigated using different turbulence models that range from the zero-equation model to the Reynolds stress model (RSM). Quantitative and qualitative comparisons were made between the numerical results and corresponding experimental data with the purpose of evaluating the performance of different turbulence models. Also investigated were the effects of the inlet boundary conditions, three-dimensional effects, and wall treatments on the numerical predictions. The results showed that all the turbulence models used in this study could capture the general flow behavior observed in the experiments, but certain differences existed in the flow patterns between the numerical predications and the experimental observations. The predicted mean velocities were closer to the measurements than the predicted turbulent kinetic energy. It was found that some turbulence models performed better in predicting mean velocities, while other models did better in predicting turbulent kinetic energy. This study shows that the selection of turbulence models should depend on the quantities being examined. [ABSTRACT FROM AUTHOR]

A novel printed antenna having a frequency band notched function for UWB application is proposed and studied. With a pair of inverted-F-shaped slots introduced around the microstrip line on the ground and inserting a semicircle-rectangle radiating element, the designed antenna satisfies the VSWR requirement of less than 2.0 in the frequency band between 2.9 GHz–11.15 GHz while showing the band rejection performance in the frequency band from 4.96 GHz to 6.03 GHz. The experiment results and characteristics of the proposed antenna are shown in this paper. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel printed wideband monopole antenna with simple structure and compact size. The proposed antenna can provide two separate impedance bandwidths of 1.55 GHz about 48.8% (from 2.4 to 3.95 GHz) and 1.275 GHz about 22.4% (from 5.05 to 6.325 GHz), making it easily cover the required bandwidths for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) operations. Also, good antenna performances such as radiation patterns and antenna gains over the operating bands have been observed. Details of the proposed antenna design and experimental results are presented and discussed. [ABSTRACT FROM AUTHOR]

A frequency notched ultra-wideband planar slot antenna is presented. By introducing a modified fractal-shaped slot to the patch, a notched band within a wide operation bandwidth is achieved. The designed antenna satisfies the voltage standing wave ratio requirement of less than 2.0 in the frequency band from 3.01 to 13 GHz above while showing the band rejection performance about 500 MHz in the frequency band of 5.59 to 6.09 GHz. Simulation and measurement results are presented for the proposed antenna. [ABSTRACT FROM AUTHOR]

A small printed antenna is described with subband rejection for ultrawideband (UWB) applications [1]. Two notches are incorporated in the radiating structure of the antenna to act as a bandstop filter to reject the undesired subband within the whole bandwidth [2]. The designed antenna features a compact size of 26×25 mm2, and satisfies the VSWR requirement of less than 2.0 in the frequency band from 3 GHz to more than 12 GHz excluding any undesired subband such as 4.65–5.65 GHz. Good monopole-like radiation patterns and antenna gains have also been obtained. [ABSTRACT FROM AUTHOR]

A novel printed wideband monopole antenna for multiband operations is presented. Good impedance matching in a wide dual-band can be achieved by a simple circular monopole and a rectangular conductor-backed plane with a square hole. The measured 10 dB bandwidth for return loss is from 1.78 to 4.19 GHz about 80% and 5.12 to 6.35 GHz about 21.4% which covering all the 2.4/5.2/5.8 GHz WLAN, 2.5/3.5/5.5 GHz WiMAX, DCS (1710–1880 MHz), PCS (1850–1990 MHz), UMT (1920–2170 MHz), and IMT-2000 (1900–2025 MHz) bands applications. Peak antenna gains have been obtained about 3.39 and 3.96 dBi for the lower and upper bands, respectively. [ABSTRACT FROM AUTHOR]

A novel trident-shaped dual-band CPW-fed monopole antenna for PCS/WLAN applications is presented. By inserting two pairs of symmetrical strips in the middle strip of the trident-shaped antenna, dual-frequency operating bands with 10 dB return-loss bandwidths of 33.7%, ranging from 1.80 to 2.53 GHz, and of about 1100 MHz centred at 5.5 GHz have been achieved. They cover the required bandwidths of the PCS band (1.85-1.99 GHz) and WLAN bands (2.4-2.484 and 5.15-5.825 GHz). Also, good radiation patterns, and 3.6 and 9.1 dBi peak antenna gains for the lower (2.2 GHz) and upper (5.5 GHz) bands have been measured. [ABSTRACT FROM AUTHOR]