Octaband WWAN/LTE Dual-Antenna System Decoupled by Two Neutralization Lines with Inductors for Smart Phones

A decoupled octaband WWAN/LTE dual-antenna system occupying a size of 80 mm × 15 mm × 6.8 mm for smart phones is proposed. The proposed antenna system consists of two antenna elements with symmetrical geometry, two neutralization lines (NLs) with embedded inductor, and an inverted-T branch. The two NLs mainly reduce the mutual coupling at the desired lower (704–960 MHz) frequency band, while the inverted-T branch mainly reduces the mutual coupling at the desired higher (1710–2690 MHz) frequency band. The fabricated prototype has a −6 dB impedance bandwidth of 0.3 GHz (0.69–0.99 GHz) and 1.2 GHz (1.66–2.86 GHz) which cover the LTE700, GSM850, GSM900, DCS, PCS, UMTS, LTE2300, and LTE2500 bands. Within these bands, the measured mutual couplings are lower than −10 dB. The measured antenna efficiencies are about 42.6%–60% and 58.3%–78.7% at the desired lower and higher frequency bands, respectively. The diversity performance and the SAR performance are also evaluated.