Wideband built-in antenna with an enclosed 3D coupling feed structure for wireless terminals is presented. With the proposed design scheme, a nine-band built-in antenna that covers GSM850/GSM900/GPSIDCS1800/PCS1900/WCDMA/Wi8ro2350/Bluetooth/WiMax 2500 is experimentally tested. This novel nine-hand built-in handset antenna is developed within the limits of a 40 x 17.5 x 6 mm(3) volume, achieving good agreement between measurement and simulation. (C) 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2306-2309, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25441