Isolation enhancement of monopole antennas and PIFAs on a compact ground plane

The isolation of closely spaced monopole antennas and PIFAs on a compact ground plane, resembling that of a mobile handset or wireless router, is studied. Significant isolation enhancement is achieved by introducing novel pairs of optimised slits in the ground plane. By properly choosing the length and separation distance of the proposed slits, they are made to resonate within the operating bandwidth of the antennas, inserting a transmission zero in the coupling path between the antennas.