Design of a Compact 4-Element GNSS Antenna Array With High Isolation Using a Defected Ground Structure (DGS) and a Microwave Absorber

This work presents a compact (125 mm diameter) wideband 4-element antenna array with a high isolation level for global navigation satellite system (GNSS) applications. The array consists of four right hand circularly polarized (RHCP) single feed rectangular patch antennas that can cover BeiDou B1 band (1561.098 MHz), GPS L1 band (1575.42 MHz), Galileo E1 band (1575.42 MHz) and GLONASS G1 band (1602 MHz) of the GNSS upper L-band (1559 -1610 MHz). The proposed array has a wide frequency bandwidth of 80 MHz with an axial ratio of less than 3 dB. The patch elements are designed on a substrate which has a high dielectric constant to achieve a compact size. A novel defected ground structure (DGS) has been introduced in the ground plane along with a MT-30 microwave absorber on the top of the array to achieve a high isolation of more than 25 dB in the entire band of interest. The proposed design has a radiation efficiency of more than 58.8 % and a peak gain of 6 dBi.