This paper presents a low-profile, single layered rectangular microstrip patch antenna designed to operate for 2.45GHz and 4.96GHz frequency band of IEEE 802.11.A rectangular patch of dimensions 18.6×26.8mm is positioned above the surface of an Alumina (Al2O3 ceramic) substrate at a height of 4mm from the ground plane and fed by coaxial feed configuration to operate at 2.45GHz frequency band (IEEE802.11b/g/n). On loading a notch over the radiating patch dual frequency behaviour of the antenna is achieved and it resonates at both 2.45GHz and 4.96GHz frequency band(IEEE802.11y). The proposed antenna has a unidirectional radiation pattern. This probe feed antenna is designed and simulated using High Frequency Structure Simulator (HFSS) v13.0. © 2015 IEEE.