Study Of HPM Power Measurement By Dipole Antenna

It is of great significance to decrease the effective area of a receiving antenna to reduce the received microwave power.Numerical simulations and experiments have been done to investigate short dipole antennas with small effective areas.Firstly,conventional dipole antenna is studied by numerical simulations,and the relationship between antenna parameters and its sizes is obtained.And based on this relationship,short dipole antenna is brought forward to measure HPM power,with the purpose of decreasing the effective area of an antenna,and accordingly reducing the received power.The characteristics of short dipole antenna with central frequency 1.75GHz have been studied through numerical simulations.The gain of the antenna varies from -23～-10dB when the length of the slot varies from 20～44mm,and the gain has the maximum value when the length of slot is aboutλ/4.When the width of slot vary from 0.6 mm to 2.0 mm,gain varies from-15 dB to -11 dB and the gain increase with the width of the slot.The effective area of the antenna is sensitive to the length of the slot and has reached the maximum value when the length of slot is aboutλ/4.It is also sensitive to the width of the slot,and the effective area varies from 0.8 cm~2 to 2.0cm~2 when the width of slot vary from 0.6mm to 2mm.The reflectivity of the antenna has reached the minimum value of 63%when the length of slot is aboutλ/4.The gain increases when frequency rises in the range of 1.15～2.25GHz.Based on the characteristic research of short dipole antennae,a short dipole antenna with central frequency 1.75GHz is designed.The radius of inner conductor of the coaxial line is 1.5mm,and the inner and outer radius of exterior conductor is 3.5mm, and 5.5mm,respectively.The length of slot is 35mm and its width is lmm.The calculated reflectivity of the short dipole antenna is 78.1%,and its gain is -12.4dB,with an effective area of 1.34cm~2.Secondly,a short dipole antenna with central frequency 3.65GHz is designed.The radius of inner conductor of coaxial line is 1.5mm,and the inner and outer radius of exterior conductor is 3.5mm and 4.5mm,respectively.The length of the slot is 10mm, and the width is 2mm.The gain of the short dipole antenna is -12.8dB with an effective area of 0.28cm~2 in S-band.And in the band of 3.45～3.85GHz,the relationship between gain and frequency is approximately linear. Finally,the feasibility of measuring HPM power with the designed L band and S band short dipole antennae has been confirmed by experiments.