Mutual Coupling Reduction in Circularly Polarized Array Using Decoupling Structure With Polarization Rotation Property

Abstract

A novel decoupling structure with polarization rotation property (DSPR) has been proposed recently to reduce the mutual coupling between co-polarized and cross-polarized antennas. Its potential application for mutual coupling suppressing of circularly polarized (CP) antennas has been briefly demonstrated using cross dipoles with ideal CP feed networks. In this paper, we further investigate its ability for decoupling of CP antennas. The cross dipole is still used as array element yet with a practical wideband feed network. Due to the DSPR&#x0027;s ability of reducing the co-polarization and cross-polarization couplings simultaneously and equally well, the couplings between CP antennas can be effectively reduced. A <tex>$1\times 2$</tex> CP antenna array and a <tex>$1\times 4$</tex> CP antenna array with working band from 3.3-3.8 GHz are adopted as examples to illustrate the reduction effect to coupling of the proposed DSPR method. With the DSPR, the isolation levels between adjacent CP antenna elements are improved by 15 dB, besides, the axial ratio in the array is reduced from 3 dB to 1 dB.