High performance of coaxial feed UWB antenna with parasitic element for microwave imaging

Abstract

A high performance of coaxial feed ultrawide band (UWB) array antenna with parasitic element is proposed in this article. The 4 × 1 array antenna consists of four identical copper circular patches are appropriately connected using quarter-wavelength transformer transmission line. The array elements and its feed network are properly optimized to have a high-gain performance over wide range bandwidth frequencies. Introduction of semicomplementary copper parasitic element with copper partial ground technique are applied in this proposed antenna to obtain optimum large bandwidth. Taconic associated with 2.2 dielectric constant and thickness of 1.6 mm is used as the antenna substrate. Less complicated fabrication methods is possible due to the feeding network placement is on the same level with the antenna patch elements. The performance of the designed antenna evaluated in term of return loss, bandwidth, radiation pattern, directivity, and gain. The proposed antenna recorded reflection coefficient less than −10 dB started from 2.5 to 12.6 GHz which fulfilling the requirement of UWB. Dimensions of 80 × 45 mm2 and maximum gain of 12.12 dB made it as small and high gain UWB antenna. The antenna exhibits a stable gain from 3.4 to 12.12 dB over the operated frequencies and has 83% of usable fractional bandwidth. The proposed antenna performance finds it very suitable to be applied in human brain microwave imaging. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:649–653, 2015