Antenna system and wireless communication device employing the same

An antenna system used in a wireless communication device, comprising:

• a first antenna that receives and transmits wireless signals;
• a second antenna that transmits wireless signals;
• a baseband microchip that electrically connects the first antenna to receive the wireless signals, the baseband microchip processing the wireless signals and providing a voltage logic signal;
• a signal sensing unit that detects user-induced pressure on the wireless communication device to generate a command signal;
• a signal comparison unit that electrically connects to the signal sensing unit, the signal comparison unit activated by the command signal from the signal sensing unit to generate an electrical signal;
• a NAND gate that electrically connects to the baseband microchip and the signal comparison unit;
• and
• a switch unit that electrically connects the NAND gate and the baseband microchip, wherein the NAND gate receives the voltage logic signal from the baseband microchip and the electrical signal from the signal comparison unit and implements logic operation to generate different switch signals, and the switch unit is switched on by the switch signals to selectively connect the first antenna or the second antenna to from different transmission paths of the wireless signals;
• wherein if the signal sensing unit does not detect the user-induced pressure, and the wireless communication device works at frequencies of radio frequency (RF) signals, the logical circuit generates a first switch signal to control the switch unit to connect to the first antenna;
• if the signal sensing unit detects the user-induced pressure, and the wireless communication device works at a non-predetermined operating frequency of the RF signals, the logical circuit generates the first switch signal to control the switch unit to connect to the first antenna;
• and
• if the signal sensing unit detects the user-induced pressure, and the wireless communication device works at a predetermined operating frequency of the RF signals, the logical circuit generates a second switch signal to control the switch unit to connect to the second antenna.

A wireless communication device, comprising:

• a main body;
• and
• an antenna system that is positioned within the main body, comprising:
• a first antenna that receives and transmits wireless signals;
• a second antenna that transmits wireless signals;
• a baseband microchip that electrically connects the first antenna to receive the wireless signals, the baseband microchip processing the wireless signals and providing a voltage logic signal;
• a signal sensing unit that detects changes of parameter(s) of the wireless communication device to generate a command signal;
• a logical circuit that electrically connects the baseband microchip and the signal sensing unit to respectively receive the voltage logic signal and the command signal;
• and
• a switch unit that electrically connects the logical circuit and the baseband microchip, wherein the logical circuit logically processes the voltage logic signal and the command signal and implement logic operation to generate different switch signals, and the switch unit is switched on by the switch signals to selectively connect the first antenna or the second antenna to from different transmission paths of the wireless signals;
• wherein the logical circuit comprises a signal comparison unit and a NAND gate, the signal comparison unit pre-stores a predetermined operating frequency of the wireless communication device and compares the predetermined operating frequency with a current operating frequency of the wireless communication device;
• the NAND gate comprises two inputs and an output, the two inputs are respectively electrically connected to the signal comparison unit and the baseband microchip, and the output is electrically connected to the switch unit;
• and
• wherein when the baseband microchip outputs a high voltage logic signal to the NAND gate, the signal comparison unit outputs a low voltage logic signal to the NAND gate, the OR gate outputs a high switch signal to control the switch unit connect the first antenna to form a first transmission path to transmit GSM signals or WCDMA signals;
• when the baseband microchip outputs a high voltage logic signal to the NAND gate, the signal comparison unit outputs a high voltage logic signal to the NAND gate, the OR gate outputs a low switch signal to control the switch unit connect the second antenna to form a second transmission path to transmit GSM signals or WCDMA signals.