收音机的原理是把从天线接受到的高频信号，经检波还原成音频信号，送到扬声器变成音波把接收到的电台高频信号，用一个变频级电路将它转化为频率固定的中频信号，然后再对这个中频信号进行多级放大，再检波，低放。由于不同频率的无线电波用途较广、接受的-The principle is the radio frequency signal received from the antenna, the reduction by the detector into an audio signal to the speaker becomes the received sound wave radio frequency signal with a frequency conversion stage circuit to convert it to a fixed-frequency IF signal and then on the multi-stage IF signal amplification, then detection, low level. Due to the use of radio waves of different frequencies wider acceptance