Two-Element Compact Antenna Arrays with Four- Branch Diversity using Directional Couplers and Phase Shifters

Antenna diversity schemes, which are effective in multipath environments, can improve the quality and reliability of a wireless link as the number of diversity branches increases. However, when multiple antennas are set inside small wireless devices, the antennas couple strongly to each other, then the communication performance deteriorates. Therefore, it is difficult to use a large number of antennas. In this paper, we propose a two-element compact antenna array with four-branch diversity using a directional coupler and phase shifters. To validate the effectiveness of the proposed antenna, we simulate a small two-element inverted-F antenna array. Then, we confirm that the correlation coefficients between any two branches are less than 0.5, and the reflections and coupling can be decreased by the proposed configuration.