Research On Electromagnetic Safety Of High-speed Train Roof Antennae For Passenger Wearing Cardiac Pacemaker In The Compartment

With the rapid development of the modern economy and the accelerated pace of life,various cardiovascular diseases have been on the rise.This has led to a continuous increase in the implantation rate of cardiac pacemakers in China.By the end of 2022,the implantation rate of cardiac pacemakers in China had reached 110 units per million people.At the same time,high-speed rail has become a popular means of transportation and the preferred choice for travel.Therefore,when patients with implanted cardiac pacemakers travel on high-speed trains,their cardiac tissues and pacemakers are exposed to electromagnetic environments for prolonged periods of time.Currently,there is no research on the health problems of passenger wearing pacemaker caused by high-frequency electromagnetic field generated by high-speed train roof antennae.This work mainly conducts numerical analysis on the health problems of passengers wearing pacemakers in the RF electric fields of 900 MHz GSM-R voice and data antennae and450 MHz wireless train dispatch antenna,and evaluates the safety of public electromagnetic exposure for passenger when traveling by train.Currently,the focus of research on electromagnetic interference with pacemaker is mainly in medical setting.The impact of high-frequency electromagnetic waves generated by GSM-R voice and data antennae,as well as 450 MHz wireless train control antenna on the electromagnetic environment inside the human body,remains inconclusive.This work first validates the accuracy of the specific absorption rate and penetration depth calculations using the finite element software COMSOL and the method proposed in this work.Then,a real-size train compartment with pacemaker-wearing passenger was constructed using COMSOL,with voice and data antennae and wireless train control antenna on the compartment roof.Numerical analysis was conducted to study the electric field intensity,SAR value,magnetic field strength of the passenger’s body and heart,and the temperature change of the heart and pacemaker after30 minutes of antenna radiation,in situations where the passenger faces or turns away from the voice antenna and when the passenger is in the middle or front of the car.The research results indicate that the electric field strength and SAR value of the body and heart facing the voice antenna are higher than those when facing away from the voice antenna.The maximum electric field strengths for passenger facing/backing to the voice antenna are 102V/m and 87.8 V/m,respectively.The average specific absorption rate(SAR)value for the human body are 0.0302 W/kg and 0.01559 W/kg,and the corresponding temperature rises are0.0161℃ and 0.0204℃,respectively.The maximum electric field strengths for the heart are27.3 V/m and 22.7 V/m,respectively.The average SAR values for the heart are 0.0102 W/kg and 0.004755 W/kg,and the corresponding temperature rises are 0.0016℃ and 0.00055 ℃,respectively.The temperature rises of the pacemaker are 0.001℃ and 0.0001℃,respectively.All values meet the safety criteria of the ICNIRP guidelines,and the temperature rises of the heart and pacemaker are both lower than their respective limits.This work also calculates the maximum magnetic field strengths in the bodies of special passenger when the antenna is running at full power continuously,which are 0.52 A/m and 0.75 A/m,respectively,exceeding the ICNIRP guidelines for magnetic fields.This situation requires attention.The maximum values of the electric field strength in the human body and heart,after being exposed to the radiation of a wireless train antenna while in the middle of the compartment,are25.9 V/m and 17.4 V/m,respectively.The average specific absorption rate of the human body and heart are 0.00123 W/kg and 0.000223 W/kg,respectively,and the temperature rises of the human body and heart are 0.0005℃ and 0.00006℃,respectively.For passenger located in the front of the compartment(directly under the antenna),the maximum value of the electric field strength in the human body and heart are 40.9 V/m and 18.7 V/m,respectively.The specific absorption rate of the human body and heart are 0.00132 W/kg and 0.00032 W/kg,respectively,and the temperature rises of the human body and heart are 0.00131℃ and 0.00008℃,respectively.Passenger located directly under the antenna receive higher radiation than those in the middle of the compartment,but in both cases,the values are below the safe limit of the ICNIRP guidelines,and the temperature rise of the human body and heart is below their respective limits.This work also calculates the maximum value of the magnetic field strength inside the bodies of special passengers when the antenna is operating at full power continuously,which are 0.17 A/m and 0.26 A/m,respectively.These values exceed the ICNIRP guidelines for magnetic fields,and this situation also should be noted.Although some individual data in the above results exceeded the ICNIRP limits,their maximum values were all found at locations such as the ankles,fingertips,and neck of the human body.The induced electric field,SAR value,and temperature changes in the human heart tissue and pacemaker did not exceed the ICNIRP standards.This indicates that the highfrequency electromagnetic radiation produced by the high-speed train roof antennae will not pose a health hazard to passenger wearing pacemaker.This work analyzed the changes in electric field strength,SAR,magnetic field strength,and temperature distribution in special passengers through numerical simulation.Based on the simulation results,it can be concluded that the further away from the radiation source,the smaller the radiation intensity received.Therefore,when choosing to travel by high-speed train,passenger wearing pacemaker should try to choose compartment with fewer roof antennae.