1：Experimental Design and Method Selection:

The methodology involves designing an ultra-wideband VCO at 110.5 GHz with ~31 GHz of BW, extracting the generated second harmonic inside the VCO efficiently, and delivering it to the antenna. A ramp generator continuously sweeps the frequency of the VCO to radiate a chirp BW of ~62 GHz at a center frequency of 221 GHz. At the Rx side, the received signal is mixed with a sample from the VCO at the fundamental frequency using a subharmonic mixer, and the generated IF signal is filtered, amplified, and delivered for further processing.

2：5 GHz with ~31 GHz of BW, extracting the generated second harmonic inside the VCO efficiently, and delivering it to the antenna. A ramp generator continuously sweeps the frequency of the VCO to radiate a chirp BW of ~62 GHz at a center frequency of 221 GHz. At the Rx side, the received signal is mixed with a sample from the VCO at the fundamental frequency using a subharmonic mixer, and the generated IF signal is filtered, amplified, and delivered for further processing. Sample Selection and Data Sources:

2. Sample Selection and Data Sources: The system is used in both focal plane and plane wave imaging setups to achieve higher lateral resolution.

3：List of Experimental Equipment and Materials:

The system is fabricated in a 55-nm BiCMOS process. Equipment includes a Rohde & Schwarz FSW spectrum analyzer, Ericson PM4 power meter, and ANSYS Electronics Desktop for EM simulations.

4：Experimental Procedures and Operational Workflow:

The Tx and Rx are implemented with specific designs to maximize the tuning BW of the VCO and minimize the conversion loss of the Rx front end. The system is characterized, and images of several objects are provided for both focal plane and ISAR plane wave imaging.

5：Data Analysis Methods:

The received signals are processed using near-field beamforming algorithms based on ISAR systems to reconstruct high-resolution images.