The analysis and comparison of the electromagnetic radiation characteristic of the Koch fractal dipole antennas

The electromagnetic radiation characteristic of the Koch fractal dipole antenna is analyzed, the logical assumption that the current along the Koch fractal dipole antenna obeys sine distribution is demonstrated, and the approximate expression of the magnetic vector potential of the Koch fractal dipole antenna is obtained. Using the magnetic vector potential, the far electromagnetic field is simulated, and the simulated results are compared with those obtained from the traditional symmetrical dipole antenna. For electrically large or electrically equivalent antennas, the results indicate that the electrical length of the Koch fractal dipole antenna has little influence on the radiation patterns. By using of this conclusion, the size of antennas can be reduced, as well as the least gain of antenna is satisfied. Therefore, it will be good for analytical design of multi-band and multi-functional antennas using fractal geometries. Finally, the rationalities of formulas and computations are validated by CST simulation.