Recent advances in software-defined radars: Chirped impulses

The software-defined radio (SDR) paradigm can be applied to radars. Novel radio-frequency (RF) chains and architectures can lead to enhanced radar schemes. After a brief review of SDR-based schemes, this work concentrates on the relevant topic of impulse-radio ultra-wideband (IR-UWB) radars. By emitting extremely-narrow impulses in time domain, these systems can achieve a great range resolution. However, one drawback is their difficulty to control their narrow waveform. On the other hand, because of its many advantages, the chirped waveform has been extensively used in radars and has become the standard employed signal. Here, for the first time, the chirped waveform is exploited in SDR-inspired IR-UWB radars, thus bringing together the benefits of both worlds. The key element in this radar architecture is a passive device shaped by smoothly-chirped coupled lines (SCCL) to produce the chirped signal. Through a developed circuit, very-narrow chirped pulses have been generated and measured.