A Decade Bandwidth SFCW RF Front-End With High Harmonic Suppression

To meet the demand for high-resolution and strong penetration capability in ultra-wideband radar systems, this letter proposes a novel stepped-frequency continuous-wave (SFCW) RF front-end covering the decade bandwidth of 0.3–3 GHz. However, ultra-wideband operation within this frequency range tends to generate in-band harmonics, which further induce ranging image artifacts that degrade radar performance—this mechanism is first analyzed in detail herein. To address this critical issue, an innovative architecture is introduced, which employs transmitter down-conversion and receiver up-conversion to suppress harmonics. By strategically selecting the intermediate frequency (IF) and local oscillator (LO) frequencies based on the 0.3–3 GHz bandwidth characteristics, potential spurious products within the target frequency range are effectively mitigated. Experimental results demonstrate a harmonic suppression rate of 45 dBc, indicating that the system provides a robust solution for high-resolution radar applications requiring low-frequency penetration and high spurious suppression.