The most important requirement of the Multiple-InputMultiple-Output (MIMO) [1][3] antenna system for smartphoneshave been a multi-band operation, low antenna correlation[4][7], and compact size [8], [9]. Due to the needs forthe scale of economy, the device manufacturers must reducethe number of hardware components and this demands anincreased number of frequency bands using simpler hardware.Newsmartphones on the global markets have to supportmore than 16 different frequency bands including globalroaming bands [10]. Furthermore, additional receive antennasare required to support 44 MIMO, and the challenges to thesize of the MIMO antennas become greater than ever.