Decoupling antenna elements of PIFA arrays on handheld devices

A novel approach for reducing the electromagnetic coupling between planar inverted-F antennas (PIFAs), built on a common ground plane and forming antenna arrays on handheld devices, is presented. The proposed technique is based on the insertion of two coupled quarter-wavelength slits on the ground plane between the antennas. By optimising the distance between the coupled slits, a magnetic resonance can be established within the operating bandwidth of the PIFAs. This resonance inserts a transmission zero in the coupling path between the closely spaced PIFAs, enabling the reduction of the coupling between them to very low levels without significantly disturbing their operating bandwidth.