Compact Circularly Polarized Patch Antenna for NTN Applications

Non-Terrestrial Networks (NTNs), standardized by 3GPP, integrate satellite constellations into 5G networks, requiring antennas optimized for direct satellite-to-device communication with maximum efficiency in the zenith direction. This article presents the design of a circular patch antenna with circular polarization (CP) for the 3GPP n255 band (uplink: 1626.5 to 1660.5 MHz), with a center frequency of 1650 MHz. Circular polarization is achieved through quadrature orthogonal dual feeding, using two microstrip lines coupled to the patch, with a phase shift of 90°. Simulations performed in ANSYS- HFSS, together with measurements of a first prototype, demonstrate a reflection coefficient |S₁₁| <-10 dB, an axial ratio (AR) of less than 1 dB in the zenith direction, a gain of 2.10 dBic, and a radiation efficiency of 75% at 1.65 GHz. With compact dimensions (80 x 80mm) and the use of an FR-4 substrate, the proposed antenna is feasible for large-scale production in IoT terminals intended for NTN applications.