Abstract:The Finite Difference Time Domain(FDTD) method was used to calculate the Voltage Standing Wave Ratio(VSWR) of a quasi-Yagi antenna. The model of the antenna was created and the mesh was generated by using model describing file. To simplify the calculating program, a Uniaxial anisotropic Perfectly Matched Layer(UPML) region was divided into six sub-regions and sub-regional symmetry was taken into account. The voltage source with lumped resistance was as excitation in the program. At last, VSWR was obtained by separating input voltage from total. A prototype quasi-Yagi antenna was fabricated and measured. The simulation result approximated to the measurement result, which proved the method had been correct.