Design of Ultra-wideband Miniaturized Quasi-Yagi Antenna Based on Characteristic Mode Theory
In this paper an ultra-wideband Quasi-Yagi antenna is designed.According to the characteristic mode theory,the traditional Quasi-Yagi antenna is analyzed.Combined with the antenna theory,the current path is increased and the working band-width of low frequency is widened by using bending and grooving techniques without changing the original antenna size.The anten-na size is 0.256 λ0×0.256 λ0×0.002 λ0(where λ0 is the wavelength corresponding to the minimum operating frequency),and the operating bandwidth is 0.78 GHz~1.58 GHz.Compared with the initial antenna,the relative bandwidth is increased from 30.0%to 67.8%.It can be seen from the front to back ratio that the antenna has good directional performance,which can meet the needs of human brain detection activities.