Small planar internal wireless wide area network tablet computer antenna

A planar penta-band wireless wide area network (WWAN) antenna with a small size of 12 × 35 mm2 for application in the tablet computer as an internal antenna is presented. The antenna is printed on a 0.8-mm thick FR4 substrate on which a radiating portion and an antenna ground for accommodating a matching circuit are formed. The antenna is mounted at the top edge of the display ground which supports a 9.7-inch display for the tablet computer. The antenna's radiating portion comprises a feeding strip, a parasitic strip short-circuited to the antenna ground, and a printed distributed parallel resonant circuit. The latter two contribute a 0.25-wavelength dual-resonance mode at about 850 MHz for the GSM850/900 operation. The feeding strip generates a 0.25-wavelength resonant mode at about 1800 MHz to combine with a higher-order resonant mode at about 2200 MHz contributed by the shorted strip for the GSM1800/1900/UMTS operation. Additionally, the matching circuit on the antenna ground replacing the function of the matching circuit that is usually disposed on the system circuit board and provides a convenient means to adjust the impedance matching of the antenna to cover the desired operating bands. Owing to the new configuration of the antenna, the size of the proposed antenna is about the smallest among the internal WWAN antennas that have been reported for the tablet or laptop computer applications. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:426–431, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26559