单谐振腔外部Q值的计算方法

 通过对带有耦合器的单驻波腔进行等效电路分析，推导出可计算带有耦合波导的单谐振腔外部Q值的反射相位法，该方法通过计算不同频率的反射相位来确定谐振频率和外部Q值。详细叙述了在CST Microwave Studio中用谐振模式求解法、直接时域跟踪法和反射相位法进行计算的步骤；用这3种方法分别计算了二次发射微波电子枪的外部Q值并和实验测量结果做了比较。结果显示3种计算方法都有很高的精度,但反射相位法的速度最快，耗时1 071 s。计算发现外部Q值与耦合口长度的4.1次方成反比。

Calculation of loaded cavity external Q

By analyzing lumped circuit of loaded resonant cavity,a new method of calculating external Q was advanced.In this way the resonant frequency and external Q can be determined with the reflected phase calculated in frequency domain.The particular calculations of reflected phase method,eigenmode method and time domain tracking method were shown in the software CST Microwave Studio.The three methods mentioned above were used to calculate the external Q of secondary emission microwave electron gun.Comparing the calculation results with measured data,it is indicated that these three methods are the same in high precision,but the calculating speed of reflected phase method is the quickest,whose calculating time is 1 071 s.At last,it is found that external Q is in inverse proportion to the 4.1th power of length of coupling window.