For sake of this Drude-Lorentz theory is not suitable for large-aperture photoconductive antenna, the calculation of terahertz radiation from biased photoconductive antenna ( Drude-Lorentz theory) is reported, and a meliorated calculation method of carriers 'density is put forward. 为了深入研究大孔径光导天线技术,在Drude-Lorentz理论的基础上,对光生载流子浓度的计算方法进行了改进,修正了其两个假设条件带来的误差,使之适合大孔径光导天线模拟计算。