Study on Design Method of Broadband Coaxial Arrester

Broadband coaxial arrester are widely used in protecting communication equipments from lightning strikes,through which lightning electromagnetic pulse(LEMP) is short-circuited to earth,but the communication signals can pass it without any loss.Geometric parameters is the most important factor which influence SPD's electrical properties.If geometric parameters derived from impedance matching of coaxial transmission line(TLs) are used directly in the modeling for HFSS simulation software,the simulating results of voltage standing wave ratio(VSWR) from HFSS are not good,or even incorrect.Some researches on how can the transmission line method and HFSS method combine together to give the expected VSWR are made.It indicates that the length of the short-circuited quarter wave coaxial line must be lengthened appropriately,then the parameters can be used in the modeling process of HFSS,and the expected VSWR designed for transmission line method can be given from HFSS simulating.The reasons of why the two methods can not give the same simulating results are analyzed,and the junction effect of the T structure may be the most important reason.