Handset 4-port MIMO antenna using slit separated PIFA and quarterwave-slot antenna pair

A closely-packed 4-port multi-input multi-output (MIMO) antenna designed for 2.4 GHz ISM band applications is proposed in this paper. The proposed antenna is a planar structure and is fabricated on a 36 mm times 36 mm times 1.6 mm FR4 epoxy board. Such a compact, planar design makes it practical to be integrated in mobile handsets. The closest separation between the antenna elements is 0.024lambda₀ and the corresponding worst case measured mutual coupling is less than -10 dB. This low antenna isolation is achieved by using slit separated Planar Inverted F Antenna (PIFA) and quarterwave-slot antenna pair. MIMO capacity measurement shows that the proposed antenna could achieve a nearly four fold increase in the channel capacity.