System Design And Experimental Verification Of Microwave Radiation Fire Detector

Since typical combustion products of fires have a strong microwave radiation,and microwaves are less attenuative to smoke and are able to penetrate shallow coverings.The use of microwave radiation enables the detection of ignitions,explosions and covered points.This tool can be a useful complement to infrared,visible light and radar fire detection methods.This paper presents a structural design and index analysis of a microwave radiation fire detector for fire detection scenarios.Meanwhile,the design and experimental verification of the prototype microwave radiation fire detector are completed for the detector’s antenna and reception system.The design and experimental verification of the prototype microwave radiation fire detector lay the foundation for the application of the microwave radiation fire detector.Firstly,based on the previous research on portable radiometers and the study of microwave radiation characteristics of fires,the design index and specifications of the microwave radiation fire detector are analyzed.The detector is based on a focal plane imaging system.The receiver is a simple,low-power direct detector structure.After research The detection band is 8 mm,the frequency range is 33-37 GHz,and the dynamic range is30-800 K.Then,the microwave radiation fire detector was combined with the need for a light weight,high resolution requirements.The lens antenna of the detector is improved by means of the super-surface technique.The design of a 4bit super-surface antenna using three laminated coaxial circular.The antenna has an aperture of 144 mm and a thickness of 1.6mm.Based on the existing feed antenna,the antenna is designed to meet the needs of fast scanning and imaging of the detector.The feeder array was staggered to meet the fast scanning imaging requirements of the detector.Antenna test results show that The feeder antenna has a gain of 26.3 d B at 35 GHz after focusing on the super-surface lens antenna,and a 3 d B beamwidth of 2.79° and 3.73°in the E-plane and H-plane,respectively.The staggered feeder array is designed to have an inter-antenna coupling of less than-30 d B,with a 12° lateral field of view and a 15° vertical field of view.Meanwhile,A direct detector receiver with a wide dynamic range,high sensitivity and high linearity is designed to cope with the high brightness of the burning material on the fire site.Gain control is achieved by adding a digital attenuator to ensure high linearity over a wide dynamic range of power input.The receiver linearity test result is 0.9999.Finally,on the basis of the designed antenna and receiver,the fire detection experiments are carried out with the designed microwave radiation fire detector.The experimental results show that the microwave radiation fire detector can detect the fire point under the shallow cover.To solve the problem of unclear contour and low resolution of the original image,the wavelet threshold denoising and super-resolution recovery algorithm are applied to optimize the image.The optimized image has clear edge contours and high resolution.