Miniaturization of logarithmic spiral antenna with modified Koch curve

Abstract

AbstractThis study proposes a unique methodology of reducing the footprint of logarithmic spiral antenna with the help of suitably scaled fractal known as modified Koch curve. In this process, first, the outer contour of the spiral arm is approximated with Fibonacci spiral which discretizes the former's geometry with a certain number of quarter circular sections. These sections are then superimposed with the iterations of modified Koch curve that leads to the miniaturization of the test antenna by 46% without compromising its spectral and radiation properties. The generalized mathematical approach has been developed to enable designing a compact logarithmic spiral antenna with an arbitrary growth factor. Finally, to validate the accuracy of proposed procedure, the prototypes having a selected growth rate have been fabricated and measured. The results such as reflection coefficient, impedance, gain, efficiency, radiation pattern, and axial ratio bandwidth of the first and second iterated modified Koch logarithmic spiral antenna are similar to the original logarithmic spiral operating in frequency range 2.00–18.30 GHz.