Design and parametric investigation of directional antenna for microwave imaging application

This study presents a new side slotted Vivaldi antenna (SSVA) with size reduction and improve gain with directive featured as compared with traditional Vivaldi antenna. A number of parameters are studied and optimised for breast imaging system over ultra-wideband frequency (3.1-10.6GHz). The parameter such as substrate type, radiating fins, cavity diameter, stub radius, stub angle is optimised to reduce the size of the antenna with better antenna performance in terms of bandwidth, gain, efficiency, and directivity. The radiating fins are modified by etching a number of side slot to enhance the gain and electrical length. The optimised size of the antenna is 45 (L)x37 (W)mm(2), 8.5mm cavity diameter, 9.5mm stub radius with the angle of 80 degrees by using Rogers 5870 substrate. Results show that the antenna has a bandwidth from 3.9 to 9.15GHz for reflection co-efficient <-10dB with directional radiation pattern. The peak gain of proposed prototype is 6.8dBi and the radiation efficiency is about 88% on an average over the operating bandwidth. The fidelity factor for face to face is 0.92 and for side by side is 0.62, which prove the directionality and lower distortion of the signal. A number of design iteration is done to achieve the optimum result of the antenna. The prototype of proposed SSVA antenna is successfully fabricated, simulated, and measured. Later, the antenna is used in breast phantom measurement system for microwave imaging application.