High-directivity fractal-vee dipoles

Abstract

Shaping of linear dipoles is a technique to achieve higher directivity. If the arms of a dipole are tilted to make a vee dipole, higher directivity and lower side lobes can be achieved (see Thiele, G.A. and Ekelman, E.P., 1980). Another way of shaping dipoles for higher directivity is by using a piecewise parabolic approximation (see Cheng, D.K. and Liang, C.H., 1982). By also letting the two arms in a dipole antenna configuration be fractal elements based on the Minkowski motif, higher directivity can be achieved (see Cohen, N., 1996). A variation of the vee dipole, referred to as the double-vee dipole, has higher directivity, lower side lobes and less back radiation than the conventional vee dipole (see Patwari, N. and Safaai-Jazi, A., 2000). We present an optimization search of a vee antenna based upon the Koch fractal curve. This design optimization search is described and the numerical results are presented. It is shown that by replacing the arms of the ordinary vee dipole with the Koch fractal curve, higher directivity can be obtained. It is also shown that by increasing the number of fractal iterations, smaller antennas with significantly higher directivity compared to the conventional vee dipole can be achieved.