Design of a Compact High Isolation 4-Element Wideband Patch Antenna Array for GNSS Applications

This work presents a compact (125 mm diameter) wideband four-element antenna array with a high isolation level for Global Navigation Satellite System (GNSS) anti-jamming applications. The array consists of four identical right hand circularly polarized (RHCP) single feed rectangular patch antennas that can cover BeiDou B1 band (1559.05 - 1563.15 MHz), GPS L1 band (1563 - 1587 MHz), Galileo E1 band (1559 - 1591 MHz), and GLONASS G1 band (1593 - 1610 MHz). The proposed array has a wide frequency bandwidth of 100 MHz (1.55 - 1.65 GHz) with an axial ratio of less than 3 dB. The patch antenna elements are designed on a substrate that has a high dielectric constant to achieve a compact size. The size of each patch element is only 32 x 32 x 5.08 mm(3). These patches are placed along the circumference of a circular aluminium ground plane of 125 mm diameter and 1.5 mm thickness in a 2 x 2 symmetrical arrangement. The edge-to-edge distance between the opposite patch elements is only 48 mm while for the adjacent elements the separation is only 27 mm. A microwave absorber material is employed to achieve an extremely low mutual coupling level over a wide frequency range (1.55 -1.65 GHz) within a compact form factor. The proposed design achieves a mutual coupling of less than -20 dB within a compact overall form factor of 125 mm diameter over the entire band of interest. The simulated and measured results of reflection coefficient, mutual coupling, null steering, null depth, and radiation pattern show that the proposed antenna array is an excellent choice for multiband GNSS applications.