A chip antenna formed by using an FR4 chip base and a folded‐loop metal pattern embedded therein for internal mobile phone antenna application is presented. The folded‐loop metal pattern is embedded in two different layers inside the FR4 chip base to achieve a compact structure, and a coupling gap is introduced to successfully excite two wide operating bands at about 900 and 2000 MHz to cover GSM850/900/1800/1900/UMTS, 2.4‐GHz WLAN, and 2.5‐GHz WiMAX operations; that is, a seven‐band internal mobile phone antenna for covering WWAN/WLAN/WiMAX operation is obtained. The proposed chip antenna also occupies a small volume of 4 × 5 × 40 mm3 (0.8 cm3) and shows a low profile of 5 mm when mounted on the system circuit board of the mobile phone, making it suitable for thin mobile phone applications. The proposed chip antenna is studied and tested. The SAR effect of the antenna is also analyzed in the study. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 543–549, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24063
A promising compact ceramic chip antenna capable of generating two wide operating bands at about 900 and 2000 MHz for covering GSM850/900/1800/1900/UMTS WWAN (wireless wide area network) operation is presented. The antenna comprises a ceramic chip base of high relative permittivity 40 and small volume 2.5 × 5 × 40 mm3 (0.5 cm3) and a simple metal pattern embedded therein. The metal pattern is of an asymmetric T‐shape with two different simple radiating arms; no meandering in the metal pattern is used, which is different from the meandered‐type metal pattern used in conventional chip antennas. Without meandering in the metal pattern, the possible large coupling between the adjacent portions in the metal pattern can be avoided. Large operating bandwidths are hence promising to be achieved. Also, without meandering in the metal pattern, the proposed chip antenna can still occupy a small volume for WWAN operation. The small volume allows it easy for the proposed antenna to incorporate the possible electronic elements such as the speaker and the lens of the embedded camera at the top portion of the system circuit board of the mobile phone to achieve a compact integration. Details of the proposed ceramic chip antenna are presented and studied. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 103–110, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24020
axial length of the helix with pitch angle 0.6 is 15% smaller than helix with pitch angle 4°in Ref. 5. The axial ratio as a function of the straight wire length is computed, and the current distribution and input impedance is given. The experimental results agree well with the simulation data, and the low profile and high polarization purity characteristics make the antenna suitable to form an array antenna in the satellite communications.ABSTRACT: A promising planar inverted-F metal-strip antenna suitable for Bluetooth headset application is studied. The antenna has a low-profile appearance and can be embedded inside the housing of the Bluetooth headset to operate as an internal antenna. The antenna is to be mounted along the side edge of the system circuit board of the headset, almost not occupying the valuable board space. Results have indicated that, when the antenna is mounted at either end of the side edge, a large bandwidth (Ͼ250 MHz) centered at about 2442 MHz can be achieved, making the antenna easily cover the Bluetooth operation in the 2400 -2484 MHz band. Performances of the studied antenna attached to the user's head are also studied. Large distortion in the antenna's radiation pattern is observed. However, the antenna's radiation efficiency is still larger than about 70% over the operating band, which is acceptable for practical applications. Details of the obtained experimental and simulation results are presented and discussed. Figure 6Measured patterns of the antenna at frequency 2.48 GHz with a ϭ 2°, and h ϭ 16 mm ABSTRACT: A systematic approach to achieving high quality gapless microlens array fabrication using the incomplete developing and thermal reflow process was developed in this study. The experimental results proved that a hexagonal microlens array with a maximum 100% fill-factor could be successfully produced. The major objective in using this robust design is to reduce the variations in microlens array focal length, allowing improved focus and enhanced illumination brightness. In this experiment, the Taguchi method was used first to perform an efficient experimental design and analyze the robustness of the microlens array fabrication process. Several parameters affect microlens array uniformity; the hexagonal column diagonal, spin coating revolution speed, exposure time, developing time, and reflow temperature. It is very important to control these parameters to decrease the sensitivity to noise. Therefore an artificial neural network (ANN) was used to minimize the variation and make the microlens array less sensitive to process variation. The L 18 orthogonal array was used as the learning data for the ANN to construct an ANN model that could predict the parameters at nondiscrete levels. The results showed the microlens array quality was significantly improved compared with the original design.
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