Calibration Stability and Localization Accuracy of a Low-Cost and Portable Breast Microwave Sensing Device

Breast cancer detection is limited in low- and middle-income countries and low-income and remote commu-nities in developed countries. Screening limitations contribute to disproportionally high mortality rates. To address these realities, a portable breast microwave sensing system was constructed using low-cost equipment. The device features a cylindrical array of twenty-four thin patch antennas each connected to a small, inexpensive Nano Vector Network Ana-lyzer (NanoVNA). Due to limitations with the NanoVNA, an enhanced response 2-port calibration method was used instead of a full 2-port calibration. The accuracy of the enhanced calibration model was compared to the full 2-port calibration using a Copper Mountain C1209 VNA. The NanoVNA cali-bration model agreed with the full 2-port model within 0.67 %. Experimental S
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measurements were performed on metal rods from 0.6 - 4.4 GHz. A radar image reconstruction method was used to extract the apparent location of the metal rods. The stability of the Nano Vnacalibration was monitored over 24 weeks, showing insignificant changes in the extracted rod positions. Correcting for positioning errors reduced the average localization error from 1.6 ± 0.9 mm to 1.1 ± 0.7 mm.