Mutual coupling mitigation in a 110-mm 4-element GNSS array with greater than 20 dB isolation and 60 MHz impedance bandwidth

This paper introduces a miniaturized quad-element antenna array with enhanced isolation levels for Global Navigation Satellite System (GNSS) upper L-band (1559-1610 MHz) applications. The presented array comprises four right-hand circularly polarized (RHCP) single-feed rectangular patch elements, which effectively encompass BeiDou B1 (1561.098 MHz), GPS L1 (1575.42 MHz), Galileo E1 (1575.42 MHz), and GLONASS G1 (1602 MHz) bands. The antenna array is designed using a higher relative permittivity material to ensure a smaller footprint. To enhance isolation across the entire band of interest, a defected ground structure (DGS) is implemented in the ground plane, along with a comb-shaped decoupling structure on the top surface between the antennas. This configuration results in an isolation exceeding 20 dB in the complete upper L-band. Additionally, the presented antenna array exhibits a gain above 6.5 dBi and maintains a radiation efficiency of more than 93%.