A COUPLED-FED LOOP ANTENNA FOR METAL-RIMMED MOBILE PHONE APPLICATIONS

This letter presents a very simple coupled-fed loop antenna for metal-framed mobile phones, which is capable of providing hepta-band WWAN/LTE operation. By utilizing the metal rim as a part of antenna, the proposed antenna only occupies a 14.5 x 8 mm(2) area of the no-ground portion. The proposed antenna consists of two coupledfed loops mainly composed of parts of the metal rim with two slits, a high-pass matching circuit, and a distributed inductor. The lower band is initially provided by the quarter-wavelength resonant mode of the longer coupled-fed loop and further widen by a high-pass matching circuit. The upper band is attained by the higher-order mode of the longer coupled-fed loop along with the quarter-wavelength mode of the shorter coupled-fed loop. Consequently, the generated two wide bands can cover the 824-960 and 1710-2690 MHz simultaneously. Besides, an antenna prototype is manufactured as well as tested, and the good measured antenna performances including reflection coefficient, radiation pattern, antenna gain and efficiency indicate that the proposed antenna is suitable for the metal-frame mobile phone applications. (C) 2016 Wiley Periodicals, Inc.