To provide an alarm sensor device and an antenna device, which fit for a microwave frequency vehicle invasion alarm unit.
The output of a low pass filter 7 is branched into first branch which has a rectifier diode and a comparator, gives a signal to the output at the time of receiving the non-carrier microwave signal to be at a corresponding level and which is highly sensitive to the signal of the Doppler frequency of 0-200Hz, and second branch which has an amplifier 8, a high pass filer 9 and a comprator 10 and given an output signal at the time of detecting the signal to be at the corresponding level, whose frequency shows interference generated outside in the band of 40-200Hz. When interference generated outside is recognized in second branching, a logic element 15 weakens the output of an alarm. The antenna device forms a rectangular radiation area, it is mounted on the roof of a vehicle and is forms an appropriate apply area in the vehicle.
TYSON PAUL ANDREW
BLUNDEN PETER PHILIP
