Improvement of radiation characteristics for the monopole antenna with asymmetric ground plane

In this study, technques of cross-polarization suppression for the coplanar waveguide (CPW)-fed monopole antenna with an asymmetric ground plane have been presented. By appropriately etching a notch and embedding a four-slot array in the ground plane, the horizontal current component of the ground plane can be efficiently decreased, thus suppressing the cross-polarized radiation at the broadside direction. Furthermore, three inverted-U strips are added above the monopole so that a good ratio of the co-polarized radiation power to the cross-polarized power can be obtained. The proposed antenna achieves the ratio of 13.20 dB at the broadside direction, to compare with the 4.36 dB for the referenced monopole antenna with an asymmetric ground plane.