This article proposes an affordable and fast microwave imaging prototype using a time-domain baseband imaging technique with ultrawideband (UWB) impulse signals. Unlike traditional methods that sample the signal at radio frequency (RF), the signal of the proposed device is self-mixed to be downconverted to baseband, and then sampled using a real-time oscilloscope with a sub-GHz bandwidth. This noticeably simplifies the receiver (RX) and speeds up the signal acquisition. The required RF section of the RX, including the low-noise amplifier (LNA) and self-mixer, is fabricated using a 65-nm CMOS integrated-circuit (IC) technology. Due to the low-frequency content of the received signals, traditional confocal imaging techniques cannot be directly used, and hence an energy-based imaging technique is also proposed. Experiments using a 3-D phantom with a skin layer show 0.5–1.8-cm localization accuracy in the detection of a 1-cm diameter tumor.

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