微波器件联接扭矩与无源互调间的关系

Relation between torque and passive intermodulation in microwave devices

无源互调是空间复杂大功率微波器件设计和卫星通信技术中的难题.为了揭示微波器件联接扭矩与无源互调功率电平间的数学关系,提出了一种快速计算方法.首先,以二项式的形式推导了互调电压的求解方法;然后,结合传输线理论建立了单点源无源互调数学模型;接着,由实验测得的微波器件I-V特性计算I-V关系式中的非线性系数,代入点源无源互调模型来计算不同联接扭矩下的无源互调功率电平;最后,设计了相应的实验,验证了点源模型预测三阶无源互调功率电平准确性,解决了微波器件在不同联接扭矩下的无源互调预测难题.

Passive intermodulation （PIM） is a complex problem in high-power microwave devices and satellite communications. In this paper, an effective calculation method is proposed for revealing the mathematical model between torque and PIM power levels of microwave devices. First, the analytical formula for the intermodulation voltage is derived based on the nonlinear I-V characteristics of microwave devices. Second, the mathematical model of point sources is constructed by the transmission line theory. And the nonlinear coefficients are calculated by the I-V curves from measured experiments. By substituting the nonlinear coefficients into the point source model, PIM power levels under different torques are obtained. Eventually, the accuracy with which the point source model predicts the three-order power level is verified by experiments, which solves the problem of PIM prediction under different torques in microwave devices.