关键词: 微波负载, 无源互调, 互调失真, 分数阶微分, 电热耦合, 热阻

Abstract:

Microwave loads are used to improve the matching performance of circuits and absorb the microwave energy. The microwave loads generate the joule heat to affect the electrical resistivity after consuming microwave energy which may produce the passive intermodulation (PIM). Electro-thermal compling leads to the difference of the time scale which produces PIM. In order to address the problem, the fractional heat conduction model of microwave loads is created by the fractional calculus firstly. Then the circuit model of the fractional heat conduction is established. Eventually, the thermal resistance effect is considered. The expression for the PIM power level caused by the coupled electro-thermal microwave loads is derived. The influences of the material's temperature coefficient of resistance, thermal resistance and thermal capacity to PIM are revealed, which provides the fundamental basis for reducing the PIM from the coupled electro-thermal microwave loads.
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Key words: microwave load, passive intermodulation, intermodulation distortion, fractional calculus, thermal-electric coupling, thermal resistance