Design and implementation of sub-GHz transmitter for ultra-wideband through-wall radar

Ultra-wideband (UWB) transmitters for through-wall radars operating in sub-GHz frequency may enable better penetrating ability and lower attenuation than devices utilizing signals above 1 GHz frequencies. In this paper, the crucial parameter of sub-GHz unipolar pulse width is investigated by theoretical analysis and experiment. Based on these parameter data, in order to radiate the signal effectively and reduce the ringing, we design a fifth-order parallel LC high-pass filter. It shapes the unipolar pulse into the bipolar pulse which has no direct current component and slight ringing. The transmitter circuit is implemented and tested. Results indicate that it generates sub-GHz UWB pulses with 2.6 ns temporal width and 744 MHz frequency bandwidth, which appears to be suitable for the through-wall radar.