About fractal antennas

Hi all,

What do you think about fractal antennas?
In his book "Electrically Small, Superdirective, and Superconducting Antennas" (Wiley, 2006) R.C. Hansen put fractal antennas among "pathological antennas", side by side with crossed-field antennas and other crazy designs whose claims would violate laws of physics.
Hansen concludes:

A careful review of the many papers on fractal antennas shows that they offer no advantages over fat dipoles, loaded dipoles, and simple loops with or without magnetic core. Nonfractals are always better.

Please give your opinions and experience. Thank you.
Regards

Z

Hello,

I think the same, there are no technical advantages. I have the book you mentioned and I like it because of the solid statements regarding structures that only work in the minds of the inventors (but not outside their minds).

When you look, for example, to the current distribution (amplitude and direction) in a Sierpinski dipole, you will see that only the longitudinal component (current components along the dipole axis) will significantly contribute to the radiation pattern. All other lateral components caused by the fractal structure generate far field components that practically cancel each other.

The only purpose I see is related with patent issues. When somebody makes a structure that really works, but with great imagination looks like a fractal antenna, the patent holder may try to get money.

Hi again,

I agree with WimRFP.
In the case of Sierpinski gasket, the multiband property is not due to its fractal structure but to the log-periodic placement of some of its gaps.
Another motivation behind that subject can be the need to generate publications.
Regards

Z