微波信号调制电路设计与实现

Design and implementation of modulation circuit for microwave signal

在智能微波开关的发射电路中,对高频微波信号采用了低频和中频两级调制的方法。为避免现场多对智能微波开关之间的相互干扰,首先用37～51 Hz分8级可调的低频高占空比方波信号调制21 kHz固定频率的中频信号,再用该信号调制10 GHz的高频微波信号。在信号调制的同时,用低频信号控制MOS管对高频微波模块的DC-DC供电电源反馈回路进行干预,使DC-DC电路工作于最佳状态,输出电压峰值平稳,避免了高频发射模块间歇式工作对电源电路输出的影响,提高了智能微波开关的测量精度和工作的可靠性。设计结果与理论分析结果比较接近,达到了设计要求。

In transmission circuit of a smart microwave switch,both the low-frequency and the mid-frequency signals are transformed into microwave frequency.To avoid several couple smart microwave switches interfere with each other, first, the 21 kHz fixed-frequency signal is modulated by a high-duty-cycle square wave signal which frequencies are adjustable from 37 Hz to 51 Hz as 8-levels. secondly, the modulated signal modulates microwave. At the same time, the low-frequency signal controls a MOSFET to regulate the feedback signal of the DC-DC circuit of the microwave module. The regulating operation makes the DC-DC circuit to work in best state, prevent effects from intermittent work of the high-frequency module. The output voltage of the DC- DC circuit is very smooth. The measuring precision and reliability are improved. Design results are close the theoretical results and meet the design requirements.