High Gain Ultrawide Band Vivaldi Antenna Design for Mini/Micro Satellite Synthetic Aperture Radar Applications

Abstract

In this paper, Vivaldi antenna array design with high gain and directivity, which works in ultra-wide band, is presented especially for Synthetic aperture radar applications in small surveillance satellites. The proposed antenna structure has been modified to improve the parameters that make up the radiation characteristic of an antenna, such as directivity, gain, return loss (S11), voltage standing wave ratio (VSWR), and antenna efficiency. Firstly, the design parameters of a single antenna element are optimized using Genetic Algorithms (GA). The optimized Vivaldi antenna structure in 44⨯49 mm dimensions offers high antenna gain and return loss(S11)below −10 dB in X-band (8−12 GHz) and Ku-band (12−18 GHz) frequency range. As a substrate, Rogers Duroid 5880 with a 2.2 dielectric constant and 0.508 mm thickness, which can be easily found on the market and preferred at high frequencies, has been used. The antenna structure, which is optimized for use in high resolution synthetic aperture radar applications, is designed as a planar antenna array. The planar antenna array (4⨯4)is formed with 16 elements. The distance between the elements and the amplitude of current is optimized by GA in order to enhance antenna gain by minimizing side lobe levels (SLL) and the grating lobes in operating band width. In this way, the side lobe level below −20 dB, the average 18 dB gain during the operating frequency and the highest 19.4 dB antenna gain at 10 GHz have been obtained. The measurement and simulation results are in agreement and the proposed antenna has been proven to be suitable for high resolution SAR applications.