A Non-Connected Decoupling Method for Three Element MIMO Antennas by Using Short Stubs

MIMO technology, which uses multiple antennas, has been introduced to the mobile terminal to increase communication capacity per unit frequency. However, MIMO suffers from the problem of mutual coupling. If MIMO antennas are closely packed, as in a small wireless terminal, a strong mutual coupling occurs. The mutual coupling degrades radiation efficiency and channel capacity. As modern terminals are likely to use three MIMO antennas, reducing the mutual coupling 3 x 3 MIMO is essential. Some decoupling methods for three elements have been proposed. Unfortunately, these methods demand that the elements be cross-wired, which complicates fabrication and raises the cost. In this paper, we propose a non-connected decoupling method that uses short stubs and an insertion inductor and confirms that the proposed model offers excellent decoupling and increased radiation efficiency.