Using surface acoustic wave (SAW) delay line as the core technology, a delay line with wide bandwidth, small in band ripple and long delay time has been developed. Through optimizing the link mode of the delay line and investigating the embedded system and communication system, a new radio altimeter exciting source operating at C band has been fabricated. The radio altimeter exciting source can be adjusted continuously from 1 m to 8 000 m in 1 m interval and has 3 dB bandwidth of 200 MHz. The system has the features of small size, multifunction, versatility and auto test.