Design and Physical Implementation of a Compact Directional Vivaldi Antenna for Microwave through the Wall Imaging Applications

Abstract

 This paper presents designs and physical implementation of a compact directional antenna with improved gain for microwave through the wall imaging application. In this design, the antenna performance in terms of bandwidth, gain, efficiency and directivity are enhanced by etching and modifying the radiating pins of the proposed antenna. Several parameters are investigated and optimised using surrogate assisted differential evolution algorithm (PSADEA) to cover frequency ranging (1-4GHz) which is typically used in the through the wall imaging applications. The electrical length of the antenna is 025ƛ x  0.37 ƛ x 0.01 ƛ at the centre frequency band. The simulation result indicates that the antenna exhibits impedance bandwidth from 1.5 to more than 3GHz for reflection coefficient less than -10 dB. The peak gain of the proposed antenna is 5.6 dBi and having fractional bandwidth of 91%. The antenna was also characterized in time domain in order to calculate its fidelity factor for face to face as 0.92 and side by side as 0.62, which indicates the lower distortion of the pulse signal.