Microwave detector Cent is microwave detector radar type and wall type detector of microwave of type of two kinds of radar 　 radar type is receive microwave one kind, the detector that sends equipment to shut place, working principle is based on a Doppler effect. The wavelengh of microwave is very short, between 1mm ～ 1000mm, because this is very easy,be reflexed by the object. The meeting after microwave signal encounters mobile object to reflex produces a Doppler effect, meet via reflexing the microwave signal after and the frequency that transmit a signal namely the deflection with tiny generation. Can think to call the police right now generation.
Use the principle that much Pu Lelei amounts to, microwave emissive antenna and receving antenna outfit are together. Use aspect effect provides source of oscillation of microwave solid state, pass the combination with wave guide, form a diminutive to launch the emission source of microwave signal. The signal mixing that the canal of demodulation of Xiao Ji spy in probe and sheet of composition of same wave guide are in charge of wave guide first detector to come back as receiver and emission source coupling, get a difference on the frequency thereby, send the control after low frequency amplifier is handled the output that call the police again. The electromagnetic wave of small wave band because wavelengh is shorter, penetration is strong, the metalloid material such as glass, board, brick wall can penetrate. Do not face when installation so outdoor, lest the somebody outdoor signs up for by accident through causing. Metallic object is stronger to microwave reflex, be on guard in detector there is not large area inside area (or volume is larger) the object exists, the ark that be like iron. Be in otherwise ever since shadow ministry branch forms exploration blind area, cause be on guard flaw. When many microwave detector is installed together, emissive frequency should somewhat difference, prevent across to disturb generation to sign up for by accident. Additional, because the 100Hz modulation signal that generates like the gas discharge illuminant such as fluorescent lamp, mercuric lamp is twinkling the athletic reflector that the ionization gas inside the lamp becomes microwave easily and cause sign up for by accident. Use microwave inbreaks detector sensitivity is not exorbitant, adjust when 2/3 relatively appropriate. Exorbitant sign up for meeting grow in quantity by accident. Like ultrasonic the family also can be used.
Detector is to the monitoring area per fire detector of target of the activity inside cautionary area stereo be on guard space, range is bigger, can enclothe 60 ° to come the horizontal spoke angle of fire of 90 ° , control area can be amounted to a few to hundreds of square metre. Of detector of radar type microwave blast off can graph and use aerial structure are concerned, use omnidirectional antenna (those who be like 1/4 wavelengh is extremely odd aerial) can arise close to the emissive limits with globose or elliptic circle, this kind can the place such as the room that suits to protect large area or storehouse. And use directional antenna (like horn antenna) can produce wide tear form or narrow the tear form that grows again can pursue, suit to protect long and narrow place, wait like corridor or passageway. Detector of type of 　 microwave wall used detector of wall type microwave field interference principle or beam block break type principle, it is a kind of microwave closes, the detector of the buy that send cent. Detector of wall type microwave by receiver of microwave catapult, emissive antenna, microwave, receving antenna, call the police controller composition.
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