Dual-band insulator design by stacking capacitively loaded loops for MIMO antennas

A compact dual-band insulator for multiple-input, multiple-output (MIMO) antennas is presented. The capacitively loaded loops are designed for different operating frequencies and printed on both sides of the substrate of the MIMO antenna of the portable devices. When the proposed insulators are inserted in between MIMO antennas, the isolation shows good improvement at both 2.6 and 3.5 GHz bands. The isolation is suppressed under - 220 dB at the lower band of 2550-2730 MHz and at the upper band of 3390-3820 MHz. The proposed insulators are also validated through measurements.