Coating TiO2 thin film with the thickness of 50 nm and the planar size of 6×6 mm2 onto a dual band meander-planar patch radiator being printed on a FR4 substrate (relative permittivity εr= 4.4) by the size of 0.4×7×33.5mm3 is demonstrated in this report. The system is for the application of 2.4/5.2 GHz WLAN (Wireless Local Area Network) dual-band operation. Experimentally, the radiation gain was increased about 30% when part of the radiator governing the lower band coated with TiO2 thin film. It is thus revealed the TiO2 thin film can be a functional device to tune the radiation gain for the patch radiator.