研究了GaAs工型偶极子光电导天线(PCA)结构参数对THz辐射特性的影响。首先利用DL(Drude-Lorentz)模型得到了光电导天线的电流解析解，结合时域有限差分(FDTD)进行半解析半数值仿真，有效地解决了纯解析解(通过光电流对时间求导数可以得到辐射的THz的相对强度)无法和PCA结构直接对应的仿真问题，也较直接全波FDTD方法计算效率高。接着，利用偶极子光电导天线的等效电路模型和等效源阻抗公式，结合实际的PCA参数，分别得到了PCA阻抗和源阻抗，说明了由于源阻抗很低，导致匹配效率较低。最后，综合考虑数值仿真结果和理论计算结果可证明，工型偶极子光电导天线的辐射效率会随着其长宽比的增加而相应增加，该结论与相关文献实测结果吻合，从而也验证了文中FDTD仿真结果、理论模型及计算结果的有效性。

Influence of the geometrical parameters of GaAs dipole photoconductive antenna(PCA) on the PCA′s radiation characteristics was studied. At first, the analytical solution of PCA′s current obtained by the Drude-Lorentz(DL) model was obtained as excitation, and the numerical finite-difference time-domain(FDTD) simulation was conducted. This had effectively solved the problem of analytical solution (where the relative intensity of THz radiation can be obtained by time derivative) which cannot simulate the influence of PCA structure parameters. Then, using the equivalent circuit model of dipole photoconductive antenna and the equivalent source resistance′s expression, both the PCA′s and the source′s impedances were obtained for the practical PCAs. And it is demonstrated that the matching efficiency is not high because of the very low source impedance. Finally, by considering both the FDTD simulation results and theoretical calculation results, it can be proved that the dipole antenna′s radiation efficiency will increase with the increase of its aspect ratio. This conclusion is found to be in accordance with the reported measured results. Thus the simulation results, the theoretical model and the calculation results are all verified.