Investigation of a Wideband Circularly Polarized Stacked-Patch Antenna for Global Navigation Satellite Systems

Abstract

State-of-the-art global navigation satellite system (GNSS) antennas, feature wideband performance that support several services across the entirety of the GNSS L-band, 1.16-1.61 GHz. However, they are typically challenging to design due to the need of a high-performance feed network that can support circularly polarized (CP) operation. In addition, many wideband GNSS antennas are large owing to lower permittivity substrates or the use of probes and air gaps. A common approach to reducing the size of these antennas is through the use of high permittivity materials, but can adversely affect some antenna performance. This thesis investigates the use of a multi-layer, uniform permittivity substrate, balancing high-performance with antenna size. This led to the development of a wideband, dual-fed aperture-coupled stacked-patch antenna driven by an adapted ultra-wideband (UWB) branch-line coupler (BLC) in an attempt to meet all GNSS antenna requirements. Antenna simulations were conducted in Ansoft high frequency structure simulator (HFSS), comparing well with experimental results attaining a gain of 2.2 − 5.3 dBic, impedance bandwidth (IBW) > 42.8% and axial ratio bandwidth (ARBW) of 20% covering the upper and lower L-band signals. A limited study into a printed circuit board (PCB) integrated antenna including the use of a stripline layer with microstrip-to-stripline transitions was attempted with preliminary results included. Finally, a modified version of the standalone antenna was successfully investigated in a 2 × 2 sequentially rotated array (SRA) which could prove valuable in future projects such as GNSS phased arrays.