Low cross-pol linearly polarized microstrip array

A technique for a linearly polarized array is presented in which each pair of adjacent elements in the array with opposite feed orientations and phases for their single-probe fed patch can generate very low cross-pol radiation. This combination of opposite feed orientations and phases reinforces the co-pol radiation from the fundamental mode of the patch, while canceling the cross-pol radiation from the higher order modes. To verify this concept experimentally, two simple 2*2 microstrip arrays with relatively thick substrate have been fabricated. The patches are designed to resonate from 1.55 GHz to 1.66 GHz with a half-inch thick foam substrate (dielectric constant=1.05). Experimental and calculated results that demonstrate the validity of this technique are presented.<>