For eight‐band LTE/WWAN operation (704–960/1710–2690 MHz) in the Ultrabook or thin‐profile tablet computer, a planar antenna of simple structure and small size is presented. The proposed antenna is obtained by modifying a simple planar inverted‐F antenna and can be printed on one surface of a thin FR4 substrate of size 10 × 45 mm2 only. The antenna's lower band bandwidth is greatly widened by embedding a proper chip capacitor of 2.7 pF at the feeding strip. This chip capacitor combines with the antenna's shorting strip can control the excitation of a parallel resonance to modify the impedance matching of the antenna's lower band such that a widened bandwidth is easily obtained to cover the LTE700/GSM850/900 operation. Conversely, the antenna's upper‐band bandwidth is also greatly enhanced by using a coupled section in the antenna's radiating strip and adding a parasitic shorted strip near the feeding strip, which lead to multiple resonant modes excited to form a wide bandwidth (>1 GHz) to cover the GSM1800/1900/UMTS/LTE2300/2500 operation. Owing to its small size and simple structure, the proposed antenna is very suitable to be applied in achieving an antenna array with high isolation for MIMO or dual talk (dual WWAN) operation. Promising high‐isolation antenna arrays formed by the proposed antennas are presented. The obtained isolation between the antennas in the antenna array is better than 12 dB, and the envelope correlation coefficient is less than 0.15 for frequencies over the LTE/WWAN bands. Details of the proposed antenna and antenna array are presented. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1928–1934, 2013

An isolation technique for two small‐size triband wireless wide area network (WLAN) multiple‐input multiple‐output (MIMO) laptop computer antennas covering the 2.4/5.2/5.8 GHz bands is presented. The proposed WLAN MIMO antennas have measured isolation of better than −21 dB in the 2.4 GHz band and −32 dB in the 5.2/5.8 GHz bands in this study. In addition to enhanced isolation achieved, good antenna efficiencies of better than about 70 and 90%, respectively, in the 2.4 GHz and 5.2/5.8 GHz bands are obtained for the two antennas. The WLAN MIMO antenna array having a planar structure of size 9 × 55 mm2 is to be mounted at the top edge of the supporting metal plate of the laptop display. The two antennas can be fabricated at low cost on a thin FR4 substrate and are of a simple structure comprising a driven strip and a shorted strip, which provides two wide operating bands to cover the 2.4 and 5.2/5.8 GHz bands. Between the two antennas, there is an isolation element formed by a protruded ground plane and a spiral open slot embedded therein. The isolation element leads to enhanced isolation between the antennas in the 2.4/5.2/5.8 GHz WLAN bands and good antenna efficiencies for the antennas as well. Details of the isolation technique for the WLAN MIMO antennas are described, and the obtained results are presented and discussed. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:382–387, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27279

An isolation technique for two small-size WLAN MIMO laptop computer antennas covering the 2.4/5.2/5.8 GHz bands is presented. The WLAN MIMO antennas show measured isolation of better than 21 dB in the 2.4 GHz band and 32 dB in the 5.2/5.8 GHz bands. In addition to enhanced isolation, good antenna efficiencies of better than about 70% and 90% respectively in the 2.4 GHz and 5.2/5.8 GHz bands are obtained for the two antennas. The two antennas are of a simple structure comprising a driven strip and a shorted strip, which provides two wide operating bands to cover the 2.4 and 5.2/5.8 GHz bands. Between the two antennas, there is an isolation element formed by a protruded ground plane and a spiral open slot embedded therein. The isolation element leads to enhanced isolation and good antenna efficiencies for the antennas. Index Terms -Mobile antennas, WLAN antennas, antenna isolation, MIMO antennas, laptop computer antennas.