适用于探地雷达应用的低振铃单周期脉冲发生器

Low ringing monocycle pulse generator for ground penetrating radar application

设计了一种新型的适用于道路检测探地雷达的单周期脉冲发生器。该脉冲发生器包含驱动电路、阶跃恢复二极管(SRD)脉冲形成电路和脉冲整形电路三部分。驱动电路可以使TTL形式的触发脉冲变为电流更大的快前沿脉冲,用来形成给后级电路的驱动脉冲;SRD脉冲产生电路选取渡越时间较小的阶跃恢复二极管结构,通过对前级电路产生的驱动脉冲整形得到负极性高斯脉冲,然后利用微带短路线、肖特基二极管和电容并联实现生成单周期脉冲和振铃抑制的功能,提高超宽带天线辐射的效率以及测量信噪比。测量结果表明,在1MHz脉冲重复频率的情况下,峰峰值最大为23V,脉冲半高宽为138ps,振铃水平为1.25%,而当脉冲重复频率提高到5 MHz,该脉冲发生器产生脉冲波形幅度和带宽基本没有太大变化。这些特征说明,该脉冲发生器具有很高的频率稳定性,且在高分辨率探测应用情景中将会有很好的表现。

A novel monocycle pulse generator for road detection ground penetrating radar is designed and demonstrated in this paper. It contains a pulse drive circuit, an step recovery diode（SRD） pulse generating circuit and a pulse forming circuit. The pulse drive circuit can make the TTL signal a sharper and stronger trigger pulse, the SRD pulse generating circuit uses a low tran sit time diode to produce a negative polarity Gaussian pulse. At last, the pulse forming circuit utilizes micro-strip short circuit line, Schottky diode and capacitor parallel structure to generate monocycle pulse and eliminate the signal ringing. Measurement results show the output of the generator is monocycle pulse with peak values of 23 V at 1 MHz pulse repetition frequency（PRF） and 1.3 ns in full width at half maximum with 1.25% ringing. When the PRF increase to 5 MHz, the amplitude and bandwidth of the pulse generator are almost the same as before. These characteristics show that the pulse generator is pretty stable under high pulse repetition frequency, and will have a very good performance high resolution detection application.