Research Of MEMS Thermoelectric Microwave Power Sensor And Microwave Radiometer

Mobile communication has been developed from 1G to 4G,and the construction and commercialization of 5G is in full swing.While microwave communication technology brings convenience to people's lives,the health problems caused by microwave radiation have gradually attracted people's attention.Therefore,it is of great significance to accurately measure the intensity of microwave radiation.With the rapid development of microelectromechanical systems(MEMS)technology,measuring the power frequency and phase parameters of microwave signals by means of MEMS technology is becoming a new research hotspot.MEMS microwave sensors mainly include thermoelectric MEMS microwave power sensors,capacitive MEMS microwave power sensors,inline MEMS microwave power sensors,ratio MEMS frequency sensors and MEMS phase sensors.Among them,the thermoelectric MEMS microwave power sensor has excellent characteristics of high reliability,wide operating frequency bandwidth and good linearity,and is also the basis of various other MEMS microwave sensors.The inline MEMS microwave power sensor can transmit the microwave signal to the lower stage while realizing the microwave signal power measurement.Based on the above background,this paper proposes a microwave radiometer based on MEMS thermoelectric microwave power sensor.Specifically,for the frequency dependence problem of thermoelectric MEMS microwave power sensor,a frequency suppression algorithm is proposed.Experiments show that the frequency suppression algorithm removes the frequency-dependent characteristic and significantly improves the accuracy of the sensor.The relative error of the sensor is less than 1.6% within the input signal power of 0-60 mW and the frequency of 5-15 GHz.In order to detect the frequency of the microwave radiation signal,a ratio MEMS microwave frequency sensor was designed.For the inline MEMS microwave power sensor,its demodulation function is proved by theory and experiment.The RF-DC signal conversion(RF-DC)circuit is designed and the combination of inline MEMS microwave power sensor and RF-DC circuit is experimentally verified.The structure can realize the demodulation of the AM signal while using the extra microwave signal to charge the charging treasure,which improves the energy use efficiency.In order to further improve the efficiency of energy use,a power management circuit based on thermoelectric-optical integrated energy harvester is designed.The integrated energy harvester can collect heat energy and light energy at the same time.The power management circuit further increases the output voltage of the collector to 3.1V,the output voltage of the sensor is finally compatible with the power interface of the general system.The final designed microwave radiometer mainly includes an antenna,a low noise amplifier,a thermoelectric MEMS microwave power sensor,a DC amplifier,a low pass filter,an analog to digital converter,a single chip microcomputer and a liquid crystal display,and a standard microwave radiometer is used to calibrate the designed microwave radiometer.The innovations of this paper are as follows:(1)The designed frequency suppression algorithm can remove the frequency dependent characteristics of the thermoelectric MEMS microwave power sensor;(2)The combined structure of the designed RF-DC circuit and the inline MEMS microwave power sensor can collect excess microwave energy.(3)For the first time,a thermoelectric MEMS microwave power sensor was used as a power detecting device in a microwave radiometer.