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A microstrip‐fed slot antenna design for wireless local area network 2.4/5 GHz applications is proposed. To achieve dual‐band operation that composed of four resonant modes located at approximately 2.28, 2.69, 5.36, and 5.94 GHz band, three separate slots are embedded into the ground plane, in which two of the slots are devised as step‐impedance types, and one of the slots is an L‐shaped slot type. By meticulously arranging the positions of these three slots located above the microstrip‐fed line, two broad operating bands that operate between 2140–2750 MHz (∼25%) and 5050–6160 MHz (∼20%) are achieved. Detail process of designing the proposed antenna is explicitly shown, and vital parametric studies were also conducted by simulation. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:983–988, 2014

fiber end under test and the fiber for detection were measured at 1.31-and 1.55-lm wavelengths using laser diodes (LDs), an optical power meter (OPM), and 3-dB coupler. When both the measured return losses at those two wavelengths were equal to $14.7 dB (from 14.7 to 15.7 dB in our experiments), the part of the fiber end under test could be identified as uneven [shown in Fig. 1 (a)]. If one of the two losses is not equal to $14.7 dB, the part can be identified as flat [shown in Fig. 1(b)]. Every part of the fiber end under test is covered under the scanning inspection areas and can be determined as uneven or flat. Consequently, the cleaved fiber end under test can be identified as successful or failed.In the experiments, the gap between the fiber for detection and the fiber under test was set to 40 lm, and each scanning distance was set to 10 lm. Typical experimental results are shown in Figure 4. In the figure, (a) and (c) show the flat parts of the inspected fiber end found using the proposed inspection method and (b) and (d) shows the SEM image of the flat end. The fiber ends in Figures 4(a) and 4(c) were found to be correctly and incorrectly cleaved, respectively. The experimental image with a correctly cleaved fiber end shows that the flat parts form a circle of about 140-lm diameter, which is a little larger than the actual 125-lm diameter fiber end. This is because a mode field area of light may radiate from the fiber end for detection. In contrast, the experimental results for the incorrectly cleaved fiber end show that half the fiber end parts are flat and the remainder is uneven. The results of the proposed inspection method and those from SEM observation are in good agreement. CONCLUSIONWe have proposed and demonstrated a novel fiber optic sensor for inspecting cleaved fiber end based on the Fabry-Perot interferometer. The sensor uses LDs, OPM, 3-dB coupler, and XY lateral adjustment stage. The images obtained for the inspected fiber ends were in good agreement with SEM observation images.ABSTRACT: The design of a hybrid antenna with double layer structures that allow multiband operation in the global system for mobile communications/digital communication systems/personal communication system/universal mobile telecommunications system and wireless local area network band bands is presented. By combining the resonant modes excited separately by the upper layer planar inverted-F antenna structure (0.88, 0.97, and 1.18 GHz) and lower layer monopole antenna type structure (1.38, 1.76, and 2.45 GHz), a dual-frequency operation with broadband characteristics can be observed, whereby the lower and upper frequency bands are operating between 0.86 and 1.00 GHz and between 1.15 and 2.63 GHz, respectively. From the experimental results, stable gain and good radiation efficiency are also exhibited within the bands of interest. V C 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1543-1548, 2012; View this article online at wileyonlinelibrary.com.

Designed electromagnetic bandgap (EBG) structures are presented for noise suppression in an 8 mm x 8 mm System-in Package (SiP) module. By embeddeding a spiral inductor, the lower suppression frequency can decrease to 2.3GHz on a 3 x 3 lattice EBG structure. For practical layout consideration, an improved EBG structure with meandering short stubs is proposed to provide a 26.4% fractional bandwidth.