Compact and printed MIMO antennas for 2G/3G and 4G — LTE mobile tablets

This paper presents four meandered MIMO antennas printed in symmetric configuration on top and bottom no-ground edges of the substrate. Two of the four MIMO antennas are coupled fed monopoles covering GSM 900/GSM 1800/1900, UMTS and WLAN frequencies whereas, the other two MIMO antennas are direct fed monopoles covering LTE 700 and WLAN 2.45 GHz. The substrate used is FR-4 with relative permittivity of 4.35 and an overall volume of 230 × 176 × 0.8 mm³. Each antenna covers an area of approximately 75 × 50 mm². The decoupling technique used in the design involves four ground slots and two coupled ground extensions. The isolation performance of the MIMO antennas is better than 15 dB over all the cellular bands covered by the antennas. The simulated and measured results substantiate a good performance of the MIMO antennas.