LTE MIMO Antennas on Variable-Sized Tablet Computers With Comprehensive Band Coverage

A two-antenna system with comprehensive coverage on 690-960-MHz and 1710-2690-MHz Long Term Evolution (LTE) bands is proposed for uses on tablets of different sizes. Two different antenna configurations are employed to reduce coupling. The main antenna is based on an inverted-F structure. Lumped element loadings are used to enhance bandwidth performance. The auxiliary antenna adopts the capacitive coupling element technique to minimize the antenna footprint and reduce its clearance distance to the ground. Implementation issues such as fabrication difficulty, design transportability across platforms, and antenna diversity gain are looked into. Measured results show moderate efficiency and good isolation characteristics with acceptable return loss in LTE bands. Its superior diversity performance is validated with measured effective diversity gain, which confirms that the proposed design is suitable for LTE multiple-input-multiple-output (MIMO) uses.