Design and implementation of compact ultra-wideband vivaldi antenna with directors for microwave-based imaging of breast cancer

A new Compact Ultra-Wideband Circularly Tapered Vivaldi Antenna with Director (CTVAD) for microwave-based breast tumour detection system is presented. By adding the slots on the back wall offset and introducing the directors at the centre of the radiating aperture facilitate focusing the E field distribution to the centre of the aperture which in turn helps to achieve narrow beam width and high gain. Compared with the other antennas, the proposed CTVAD is compact of size 48 mm x 45.7 mm and improves the impedance bandwidth with reduced sidelobe level. The measured results show that the return loss is significantly improved in the frequency band (3.1 GHz-10.6 GHz). A unidirectional radiation pattern, flat group delay, system fidelity factor greater than 90% and FBR value more than 9 dB are achieved. Furthermore, a 3-D breast model with a spherical tumour of size 5 mm is designed using the software CST microwave studio and it is illuminated by 2 x 10 proposed CTVAD antenna array and the backscattered signals are recorded. Then the image reconstruction algorithm is implemented with the help of MATLAB software to form the image of the backscattered energy. The imaging results suggest that CTVAD antenna is a suitable candidate to construct a device that can detect breast tumour.