Effect of fractalization on the characteristics of a printed quadrupole antenna for the gigahertz frequency range

Background. Miniature quadrupole gigahertz receiving and transmitting antennas with circular radiation polarization are of interest for high-speed stable 5G wireless communication systems, including those with unmanned aerial vehicles. In addition, such antennas must be multi-band with the ability to quickly switch from one operating frequency to another. The problem can be solved by using quadrupole patch antennas, including those with a two-way patch. Recently, publications have also begun to appear advertising fractal antennas that combine fundamental multiband with compactness due to scale invariance. However, there are works in which the advertised advantages of fractal antennas are denied. Aim. Investigation of the real effect of fractalization on the characteristics of a printed quadrupole antenna for the gigahertz frequency range. Methods. This goal is achieved by using electrodynamic modeling in the CST Microwave Studio software package by comparing the obtained characteristics of the initial canonical antenna and its three fractal iterations. Results. A two-sided patch antenna made of a bilaterally foiled dielectric with a relative permittivity of 3.55 mm and a thickness of 0.203 mm, consisting of two quarter-wave dipole antennas connected in parallel, is investigated. For the initial non-fractal antenna and its three fractal iterations according to the “Sierpinski square carpet” type, 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. By step-by-step simulation of the number of iterations of the fractal structure of the above type of the printed quadrupole antenna in the frequency range up to 100 GHz, it is shown that its fractalization does not introduce significant changes in the characteristics, but only leads to a complication of the design and an increase in the cost of the antenna.