Miniaturization of logarithmic spiral antenna with modified Koch curve

Abstract

This 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.

Design of a compact magneto‐electric dipole antenna

“…A low-profile ME dipole was designed in Kaddour et al, 19 which has a thickness of 0.1λ 0 by loading capacitors. Additionally, fractal structures [20][21][22] can also be used to improve antenna performance, such as by extending bandwidth, and reducing antenna size, by utilizing the self-similarity and space-filling properties of fractal structures.…”

Wideband printed slot antenna using Koch fractal metasurface structure

“…B. Mandelbrot to describe a family of complex shapes, some of them having an inherent self‐similarity in their geometrical structure. Koch curve, a typical fractal metasurface structure, has been used to develop wideband, multiband or miniaturized antennas . Here, the boundary of the printed slot antenna in this letter was etched by Koch metasurface structure to enhance the impedance bandwidth.…”