Koch boundary on the square patch microstrip antenna for ultra wideband applications

In this paper a novel compact microstrip feed square patch antenna with right angled isosceles Koch fractal geometry on its edges is designed for ultra wideband applications. The radiating patch is modified in several steps to achieve a multiband circularly polarized antenna. The fractal antenna is simulated using CST Microwave Studio Simulator. Antenna’s performance is then compared with equilateral Koch, Minkowski and Sierpinski fractal geometries. The suggested antenna is assembled on FR4-epoxy (εr = 4.4) substrate with dimensions 60 × 55 × 1.59 mm3. The developed antenna efficiently operates at 4.3 GHz, 5.0 GHz, 6.1 GHz, 7.4 GHz, 8.9 GHz and 9.2 GHz. Circular polarizations are achieved near four resonant frequencies, which are realized by adding a circle in the middle of the patch. The presented antenna has a good gain, bandwidth, VSWR and axial ratio bandwidth. In this paper, an approach for multiband antennas is proposed. The novelty of the paper lies in the fact that a right angled triangular Koch curve is formed on the edges of the square patch.