A handheld GPS device has a device body. A base band processor is installed in the device body. Three antennas with high directivity are respectively installed perpendicular to three surfaces of the device body for receiving GPS signals. A control device is coupled to the base band processor and the antennas with high directivity. At least two switches are respectively coupled to the control device and each of the three switches corresponds to one of the three antennas with high directivity. One of the switches enables the control device to permit the base band processor receiving GPS signal from the corresponding antenna with high directivity when the frame triggers one of the switches.