A HIGH PERFORMANCE UWB ANTENNA DESIGN FOR MICROWAVE IMAGING SYSTEM

In this paper, a new design of ultra-wideband (UWB) antenna is reported for a microwave imaging system aimed to cover the UWB bandwidth from 3.1 to 10.6 GHz. The structure has a very simple Hibiscus petal pattern patch with tapered microstrip fed a line and partial trapezoid ground plane. The gap between the Hibiscus petal pattern patch and partial ground of the antenna are optimized to achieve wide impedance bandwidth. Results show that the antenna has a fractional bandwidth of about 120% from 3.04 to 11 GHz with S-11 < -10 dB with stable omnidirectional radiation pattern. The average gain of proposed prototype is 5.1 dBi and the radiation efficiency is about 85% on an average over the bandwidth. The fidelity factor for face to face is 0.8469 and for side by side is 0.9232 which represent the lower distortion of signal. The characteristics of proposed antenna are successfully simulated, prototyped and measured. Fairly good agreements between the simulations and measurements have been achieved. The reported antenna has a better impedance match and mutual coupling that provides a practical approach to realize the antenna for the UWB microwave imaging system. (C) 2016 Wiley Periodicals, Inc.