Quasi-fractal axial-symmetric structure feeded by segment of nongrounded coplanar line

Abstract

Background. Developments in telecommunication technologies and global implementation of wireless systems calls far new types of antenna systems. Microstrip antennas look the most promising in this field since they possess multiband operation capability with small dimensions and low weight, high degree of integration with other microstrip circuits and can be used as elements of phased antenna arrays.

Objectives. The goal of this paper was to simulate electrodynamic characteristics of quasi-fractal radiating structure with complex composition based on a microstrip monopole, to optimize parameters of the excitation element in the form of unshielded coplanar waveguide segment.

Matherials and methods. Quasi-fractal radiating structure with complex composition based on a microstrip monopole consists of dielectric substrate, microstrip monopole with quasy-fractal aperture, an unshielded coplanar waveguide segment. The analysis was based on the Finite Elements Method with Integral Equation Method used to account for electromagnetic fields at infinity.

Results. Within scope of numerical simulation spectral characteristics of the antenna were analyzed. Comparative analysis of spectral characteristics of canonical disk resonator excited with a microstrip line segment and canonical disk resonator excited with a segment of a coplanar line with eigenmode spectrum of a quasi-fractal excited with a segment of a coplanar waveguide was performed. Influence of dielectric substrate permittivity value on frequency and power characteristics of the radiating structure was studied. It was shown that variations in dielectric permittivity value lead to significant changes of frequency response in the higher frequency band only, wherein increase of dielectric permittivity value leads to a shift of frequency response minima towards lower frequencies of the given frequency band. It was determined that radiating structure is dualband and bandwidth of operating bands was different. Lower frequency bandwidth on dB was , and higher frequency bandwidth was  . Numerical simulation of power characteristics was performed with the radiation patterns presented as elevation patterns with fixed azimuthal angle at various frequencies. Possible methods of radiating structure parameters correction with the goal of improving power characteristics and external circuits matching were given.

Conclusions. Within scope of numerical simulation was determined that the given quasi-fractal radiating structure with complex composition based on a microstrip monopole can provide effective radiation with acceptable parasitic loss rate. The structure can provide acceptable level of external circuits matching in wide enough frequency band. The ability to form radiated fields with given characteristics in two operating bands.