A Circularly Polarized Microstrip Antenna with Dual Circular Polarization Using a 90° Hybrid Coupler and Proximity-Coupled Feeding for LTE 43 5G Applications

This paper presents a circularly polarized (CP) microstrip antenna with dual circular polarization that is fed using a 3 dB 90° hybrid coupler to ensure dual-CP radiation. The proximity-coupled structure is used as a feeding technique to obtain a larger operational bandwidth that covers the standard LTE 43 of the 5G mid-band applications (3.6–3.8 GHz). The antenna was fabricated on an FR4 dielectric substrate with overall dimensions of 66.1 × 35 × 1.6 mm3. A circular patch was formed as a radiating element, with four identical slits that were etched on the patch to guarantee the presence of CP radiation at the required mid-band of the 5G frequency range. The measured impedance bandwidth (BW) of this antenna was 10.6% (3.46–3.85 GHz), while the 3 dB axial ratio bandwidth (ARBW) was 8.2% along the range (3.50–3.80 GHz). The measured average gain was about 1.3 dBi along the antenna impedance bandwidth.