Low Profile Ultra Wideband Antenna Applied To Security Inspection Instrument

Recently,behind the rapid economic development,various security risks in public places have posed a threat to the social harmony.Therefore,people put forward higher requirements for the performance of security detector.Miniaturized security detector has many advantages and the antenna is the key component of the signal receiving part of the security system.The miniaturization of the antenna is of great significance to the miniaturization of the security system.The low profile UWB antenna has attracted wide attention because of its low profile and wide bandwith,which is conducive to miniaturization.Five antennas suitable for research background are proposed in this paper.They are bow-tie antenna,multi-loop antenna,planar logarithmic periodic antenna,archimedes helical antenna and Eleven antenna.CST is used to simulate,and the performance,the merits and the demerits of them are compared and analyzed.Bow-tie antenna and multi-loop antenna are simple dipole antennas.Based on the detailed study of the relationship between the structure and performance of them,the design schemes of the two antennas are given.In order to solve the problem of split of the radiation patterns in high frequency,the one-direction radiation is realized by adding absorbing materials in the reflecting cavity at the expense of gain.The bowt-tie antenna can achieve dual-line polarization,while the multi-loop antenna can only achieve linear polarization because of the size limitation.Both planar logarithmic periodic antennas and archimedes helical antennas have the self-complementary structure.The radiation patterns of these two antennas are not split at high frequencies.However,in order to optimize the VSWR of the logarithmic periodic antennas,absorbing materials are added to their reflecting cavities.The gain of Archimedes helical antenna is higher because there is no absorbing material in its reflecting cavity.In addition,both antennas have a 10 dB beam bandwidth greater than 100 degrees and a relatively moderate size.The design of Eleven antenna begins with discrete-fed linear polarization antenna,and goes from shallow to deep into dual-line polarization,coaxial-fed dual-line polarization and miniaturization of antenna by bending arm.The simulation results show that the Eleven antenna has high gain,more than 100 degree beam bandwidth and dual-line polarization characteristics.The disadvantage is that the size of Eleven antenna is large.