Patent ID: 6201505
Filing Date: 2001-03-13
Classification: H01Q

Abstract:
A glass antenna device for an automobile, comprising:a glass sheet sized to fit a rear window opening of an automobile;an electric heating defogger Crowded on the glass sheet and having heater strips and bus bars configured to feed a current to the heater strips;an antenna conductor provided on said glass sheet;a choke coil connected between at least one of said bus bars and a d.c. power source, or between the at least one bus bar and a body of the automobile as a ground so that a signal in a first frequency band and a signal in a second frequency band which is higher in frequency than the first frequency band are received;a receiver configured to receive a first signal in at least the first frequency band from the defogger which functions as an antenna that receives said first signal in at least the first frequency band and sends the first signal to the receiver, and to receive a second signal in at least the second frequency band from the antenna conductor which receives said second signal in at least the second frequency band and sends the second signal to the receiver;a first inductance element electrically connected between the defogger and the receiver and between the antenna conductor and the defogger by interposing at least one of a signal line and a circuit element;a second inductance element electrically connected between the defogger and the automobile body as a ground by interposing at least one of a signal line and a circuit element; anda filter circuit configured to perform one of blocking and attenuating a signal in the second frequency band and electrically connected between the antenna conductor and the defogger, whereina first resonance is generated by a resonance element which comprises the impedance of the defogger and the inductance of the first inductance element,a second resonance is generated by a resonance element which comprises the impedance of the defogger and the inductance of the second inductance element, andthe resonance frequency of the first resonance and the resonance frequency of the second resonance are such that the sensitivity of a signal in the first frequency band is increased.