Are there any ways to fool a motion sensor?

Hi I used to work as a security guard for 13 months. If your asking about how to bypass home-security motino sensor.... then i had no idea about how to answer that. On the other hand, if you have a very powerful flashlight, it will trigger the sensor causing the system to go into alarm. If youn stand outside the window of the house and point the flashlight at the sensor inside the house, causing the system to go into alarm mode say 5-10 times in a row. The security guard will get pissed off and thinks the system is broken and he will disable that one sensor till someone comes home and disarms the system. This is not really bypassing the sensor.. more like social engineering. I'm glad the first contributor wasn't guarding my home. Here he is giving burglary lessons. Actually, the only foolproof way to fool a motion detector is, DO NOT MOVE. It depends on what type of sensor it is some of them use a tunnel-diode which will oscillate at a frequency defined by the size of the cavity it is in. there is a second tunnel-diode in the same cavity it looks for changes in the signal within the cavity. so if you point a powerful tunnel-diode oscillator at the sensor which is tuned to the same frequency then it will not trip... that is if you get the frequency correct the first time, if you go in between your transmitter and the receiver then it will trip. there is a second type of motion sensor which uses IR and those can be fooled the same way. i have never tried any of these methods and they are all hypothetical and they will most likely not work because you must MOVE the transmitter in front of the detector. so it is not easy, or sane. There are also ultrasonic motion detectors. If the sensor is an IR one, I heard if you are to heat the room up to over 100 degrees, it would not be able to differentiate a person from the background as everything will be the close to the same temperature. This comment is for informational use only, lol