Response Characteristics Of Yagi Antenna To High Altitude Nuclear EMP

The nuclear electromagnetic pulse has the characteristics of high intensity,wide-band spectrum,extremely short rise time delay and large damage range,which will influence thousands of kilometers far from the explosion site's electromechanical equipment.At the same time,nuclear electromagnetic pulse(EMP)often causes electromagnetic interference to the radar antenna and outdoor antenna at a certain height from the ground,and the antenna is generally located outside the equipment,so it is vulnerable to electromagnetic pulse interference.At the same time,most of the previous studies focused on the exploration of the electromagnetic pulse characteristics of the antenna,and did not put forward specific protection measures.Therefore,based on the research of antenna impulse response characteristics,this paper also studied the protection method of antenna shield,and put forward specific electromagnetic pulse protection measures.In the second chapter of this paper,the generation principle,waveform data,coupling path and electronic destruction ability of EMP environment are briefly introduced and analyzed.Finally,the most commonly used IEC standard pulse waveform is selected as the excitation source to explore the coupling characteristics of Yagi antenna under different conditions.In the third and fourth chapter of this paper,the antenna,metal shielding cavity and excitation are established by CST electromagnetic simulation software By observing and analyzing the induced current,voltage,computable power and deposition energy of the 50 ? load connected to the antenna end,the electromagnetic pulse response characteristics of the antenna with the height of the antenna from the ground H,the incident angle of the pulse ?,the placement direction and the size of the antenna are discussed.When the shape,area and thickness of the aperture of the metal shielding cavity change,the shielding cavity will be changed The response characteristics of the antenna to the nuclear electromagnetic pulse can be deduced from the shielding effect of the body to the electromagnetic pulse,and some effective measures related to the electromagnetic protection of the antenna are summarized.Through the analysis of simulation results,it is found that:(1)From the time domain antenna coupling waveform,the coupling voltage waveform of the Yagi antenna is the oscillation attenuation wave;from the frequency domain coupling waveform,the energy coupling to the antenna reaches 98% within 100 MHz,which is consistent with the frequency domain characteristics of the incident nuclear electromagnetic pulse.Moreover,the electromagnetic coupling voltage,instantaneous power and deposition energy of Yagi antenna will increase with the increase of oscillator length and radius,but the increase range is not large.(2)The shielding performance of Yagi antenna external shielding metal cavity reduces when the aperture area raises,and the thicker the metal cavity is,the better the shielding performance of the cavity is.At the same time,the closer the antenna is to the slot,the greater the induced current coupling electromagnetic pulse to the antenna,that is,the worse the shielding performance of the cavity.The experimental results offer some advice for the manufacturing process of Yagi antenna and the protection of antenna system against HEMP.