Circularly polarized 2 × 2 fractal antenna array for space borne tracking applications

Abstract

A corporate feed sequentially rotated 2 × 2 circularly polarized fractal antenna array is investigated in this work. Four number of compact circular fractal antenna elements are positioned symmetrically across the geometry. The antenna elements in the subarray are incorporated with 1st order Koch fractal cuts and rotated with respect to its neighbor and the phase change thus generated becomes offset with the phase change in the excitation in the corporate feed. A 2nd order Minkowski fractal curve is implemented on the ground plane to optimize the radiation performance of the array. The proposed fractal antenna array (FAA) is powered with a coaxial feed, with its pin connected to the asymmetric line configuration placed on the top surface. The dimensional confinement of the array is limited to 0.904λ0 × 0.876λ0 × 0.012λ0 (fr = 2.27 GHz) and the overall layout of the geometry is built on a FR4 substrate having a dielectric constant of 4.4. The circularly polarized radiation characteristics of the elements are developed as a result of fractal cuts along the vertical and horizontal sides. A maximum gain response of 5.4 dBic is observed in the impedance band ranging from 2 GHz to 2.5 GHz. The measured results of the proposed array are found to be in good agreement. In quantitative comparison with a few existing arrays with respect to its diverse performance the proposed CP FAA is found to be suitable for space-borne applications operating in the S-band.