Low correlation handset antenna configuration for LTE MIMO applications

Multiband operation and especially spatial receive diversity requirement of portable LTE devices pose a huge challenge for a small terminal antenna design: In addition to the coverage of frequencies used in current wireless technologies, operation at new frequency bands is required. Especially deployment of the band at 700 MHz is challenging due to miniaturized size of terminal devices. Effective MIMO system requires multiple antennas receiving uncorrelated signal. In case of small handset devices in which the antennas are unavoidably closely spaced at least in frequencies lower than 1 GHz, the antenna radiation patterns should be dissimilar in order to reach low correlation between the signals received by separate antenna branches. A novel active antenna solution and a compact passive antenna both applicable in small handsets covering LTE bands 12, 13, 14 and 17 (698-798 MHz) as well as band 7 (2500-2690 MHz), GSM850 (824-894 MHz), EGSM900 (880-960 MHz), PCN (1710-1880 MHz), PCS (1850-1990 MHz) and UMTS (1920-2170 MHz) are presented in this paper. Different MIMO configurations are constructed of these antenna designs. It has been shown that it is possible to reach low correlation between two closely spaced, effective handset antennas even at 700 MHz.