Directional Antenna with Circular Polarization in the UHF Range

In this work, a technologically advanced and easy-to-manufacture directional antenna was modeled, then manufactured and investigated for the frequency range of 860-930 MHz with circular polarization. The design was based on a circular patch with an air substrate, a passive element for bandwidth expansion, and two slots for creating circularly polarized radiation. The following parameters were obtained in the model: beamwidth ~60 degrees, directivity coefficient 9.5 dB at the central frequency, and a matching bandwidth with a VSWR less than 2 from 840 to 930 MHz. The manufactured prototype had the following characteristics: gain 6.8 dB, beamwidth ~50, matching bandwidth from 760 to 950 MHz.