Spiral Planar Antenna for MIMO

A high gain spiral planar antenna for the multiple-input and multiple-output (MIMO) is proposed and fabricated in the frequency band of 2.4GHz. Its maximum and average gains are higher than those of the commercialized antenna. Two fabricated antennas are put adjacent to the same and reverse direction, and MIMO antennas are composed. The return losses in two MIMO antennas are about the same as those in the single antenna. Also, the isolation losses in two MIMO antennas are less than -10dB in 2.4GHz band even if the distance between two antennas is 0mm. The average gains of two MIMO antennas are less than those of the single antenna, but high enough to be practical.