Characteristics of a gigahertz patch antenna of the «fractal tree» type

Background. According to a number of researchers, fractal antennas, including those for the gigahertz frequency range, have a fundamental multi-frequency, which makes it possible to reduce their number in a compact device for wireless communication designed for various operating bands. At the same time, there are publications in which such an advantage of fractal antennas in comparison with their canonical counterparts is denied. It is important to note that a fractal is different from a fractal. There are fractals obtained by scale-invariant fragmentation of some initial object («Sierpinski gasket», «Koch curve», «Cantor set», etc.). But there are also fractals obtained by scale-invariant branching of the original object («fractal tree», «Julia set», «Newton basins», etc.). There is reason to believe that antennas created on the basis of fractals of fragmentation and branching will have different properties. Aim. Investigation of the characteristics of a fractal patch antenna of the «fractal tree» type, designed for the gigahertz frequency range, in its various iterative approximations. Methods. This goal is achieved by using electrodynamic modeling in the CST Microwave Studio software package by comparing the characteristics of a gigahertz patch antenna obtained for the first three iterations of the fractal tree as a prototype of a fractal antenna. Results. Quasi-fractal patch antennas (the first three iterations) of the «fractal tree» type in the form of an ideally conductive patch on a dielectric substrate with a relative permittivity of 3,55 mm and a thickness of 0,203 mm, on the opposite side of which there is a grounded metal shield, are studied. The frequency dependences of the element S11 of the scattering matrix, the standing wave coefficient of the voltage and the input impedance are constructed. The radiation patterns of the studied antennas in polar and spherical coordinates at the observed operating frequencies are also presented. Conclusion. Step-by-step simulation of a «fractal tree» type patch antenna in the frequency range 0-50 GHz has shown that as the branched type fractal evolves, the number of antenna operating bands can be increased.