S. Komeylian - Department of Electrical Engineering, Iran University of Science and Technology, Tehran, Iran.
M. Tayarani - Department of Electrical Engineering, Iran University of Science and Technology, Tehran, Iran.
S.H. Sedighi - School of New Technologies, Iran University of Science and Technology, Tehran, Iran.

kground and Objectives: Microstrip patch antennas are widely used due to their advantages of compact size and easy fabrication compared to other types. However, they have low-performance parameters. As a result, several techniques are used to improve performance parameters in newly designed microstrip antennas. In this study, a novel miniaturized microstrip antenna with circular polarization (CP) is proposed for GNSS applications.Methods: In the design process, the semi-fractal structure is used to reduce the antenna size. Circular polarization is generated using a three-feed configuration with ۱۲۰◦ phase shift. The CP value is increased by use of perturbing slots and also removing the corners. The novel design of the feeding network and also considering the ground size same as the patch layer, keep the antenna size small. The co-axial probe is used in the feeding network and it is printed on Taconic RF-۴۳ substrate with a low loss tangent of ۰.۰۰۳۳. Numerical simulation is applied via CST commercial software to evaluate the antenna performance. The simulations are repeated in two other software, HFSS and FEKO, to validate the study. Results: The proposed antenna has a compact size of ۱۷.۵۶ cm۲. The single-layer structure of the designed antenna leads to easy fabrication feature. The proposed antenna has a bandwidth of ۵۵ MHz (۱.۵۵۸-۱.۶۱۴ GHz). It can operate at GPS L۱ (۱۵۷۵ MHz), GLONASS G۱ (۱۶۰۲ MHz), Galileo E۱ (۱۵۸۹ MHz), and E۲ (۱۵۶۱ MHz) bands. Results show a high front-to-back ratio (FBR) of ۴۰ dB, RHCP gain of ۳.۴۵ dB, and pure CP with axial ratio (AR) beamwidth of ۱۰۸⸰. Furthermore, the phase center variation (PCV) is less than ۰.۱۶ mm.Conclusion: Key features of the proposed antenna are its novel fractal structure that leads to compact size, high front-to-back ratio, wide RHCP beamwidth with desirable bandwidth, and axial ratio beamwidth.

Miniaturized aAtenna, Low-profile Antenna, Semi-fractal Structure, Multiple Feed Configuration, Pure Polarization