Signal correlation of two spatially closed normal-mode helical antennas in a multipath environment for diversity reception

In a multipath signal environment, antenna diversity is an effective means to tackle the short-term fading problem and improve the signal receiving quality. In the spatial diversity scheme, keeping a small correlation of the signals received by different antennas is an important consideration for achieving a high diversity gain. It has been shown that by using the mutual coupling effect between two monopole antennas, a low signal correlation can be obtained even at a very small separation between the two monopole antennas. In wireless communications, helical antennas are frequent substitutes for monopole or dipole antennas due to their smaller size. In this paper, we present a study of the signal correlation of two closely spaced normal-mode helical antennas in a multipath environment.