Özet:

In this study, a novel ultrawide band (UWB) antipodal Vivaldi antenna with three pairs of slots was designed to be used as a sensor in microwave imaging systems for breast cancer detection. The proposed antenna operates in UWB frequency range of 3.05-12.2 GHz. FR4 was used as a dielectric material and as a substrate for forming the antenna that has a compact size of 36 mm x 36 mm x 1.6 mm. Frequency and time domain performance of the proposed antenna have been investigated and results show that it meets the requirements for UWB radar applications with linear phase response, nearly constant group delay, ultrawide bandwidth, and directional properties at most of the operating frequency. Then, the capacity of the proposed antenna as a sensor was tested in a monostatic microwave breast imaging system that was developed in the CST Microwave Studio (CST MWS) simulation software. In the simulation application, 50 mm radius hemisphreical breast models with different densities were formed and 2 mm diameter spherical tumor was placed inside them. Antennas were positioned cylindrically around the breast to send Gaussian pulse and collect backscattered signals. After signal processing steps, tumors were screened at correct positions with high resolution. Finally, a monostatic radar-based breast phantom measurement system was developed to automatically scan the breast phantom in the prone position. To perform experimental measurements, an electrically and anatomically realistic homogeneous breast phantom with tumor inside was fabricated. Screening of the tumor at correct location indicates that the proposed antenna and the microwave imaging system developed using this antenna are suitable for the detection of breast cancer at the early stage.

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