Design Of A Combinative Broad Bandwidth Antenna Used Between 25MHz～2GHz

The frequency range of EMC test is very broad. If the usable bandwidth of the antenna used in EMC test is too narrow the quantity of antenna will be unacceptable. So in EMC test the bandwidth of antenna is commonly broad.The task of this thesis is to design a broad antenna combined by bow-tie antenna and logarithm periods dipole antenna(LPDA) used in RF absorber arch test, radiant susceptibility test etc.On the basis of calculation about the input impedance of bow-tie antenna in low frequency region by HFSS, and combined bow-tie with LPDA by a well designed balancer, this article improved a LPDA that was used between 200MHz and 2GHz to a new LPDA that can be used between 25MHz and 2GHz. In the wider region, the antenna's VSWR is less than 2. This is the anticipant result.