Development of an H-shaped antenna with FR4 for 1–10 GHz wireless communications

Wireless networking is now central to modern life, and is anticipated to become ever more pervasive. Therefore, there may be several possible uses for combining lightweight fabric antennas. A flexible fabric is used to increase convenience, and the inclusion of antennas in garments ensures they do not have to be hand-held. Wireless deployment, a single-feed and a dual-frequency H-shaped antenna is presented. The transmitting model is used to build the H-shaped antenna. Varying the dual frequency is achieved with the aid of a capacitive range between 3.85 and 1.88 pF and a Zener diode. The operating frequencies for the cellular implementations of the H-shaped antenna are 2.5–4.5 GHz. The configuration of the antenna is built on an 80 mm × 60 mm dielectric by using FR4 epoxy substrate; the scale of the switch dimension is 0.7 mm × 1.4 mm with relative permittivity of 3.68 and the height of the substratum is 1.6 mm. The patch of the planned structure is supplied by a 50 ohm matching impedance co-axial cable. In this research work the proposed antenna structure gain is 8.2 dBi (86%) for wireless devices. Under the current structure, the high and minimal return losses are from –39.05 to –18.68 dB. The highest and lowest Voltage Standing Wave Ratio values of the proposed structure are 1.78 and 1.02, respectively.

Dimension Error Analysis and Simulation of Sheet Metal Multistage Assemblies

The dimension quality of sheet metal subassembly（SMS）, which is usually assembled in the multistage process, has serious effect on its performance. Based on the multistage transmitting model of dimension errors of SMS, this paper detailedly analyzed the dimension errors of SMS in locating phase, over-locating phase and springback phase, and also simulated their dimension errors by Matlab and FEM, and finally predicted the assembly dimension errors of aeroplane wainscot subassembly sample.

Using Stress Wave Based Technology for Wood Material Nondestructive Testing

Stress wave based technology has its special advantages in the field of wood nondestructive testing and quality evaluation. To analysis the propagating properties of stress wave in the wood material, a transmitting model in anisotropic material was introduced in rectangular and cylindrical polar coordinate system. The relationship between stress wave propagation and elastic constants was shown. The propagating of stress wave in wood material and the possible solutions with different parameters were studied. The transmitting character of stress wave in symmetry planes was analyzed, and the elastic constants of woods were used to compute the stress wave propagation in wood material.