Miniaturized Clover-Shaped Patch Antenna With Improved Phase Center Variation and Circular Polarization for GNSS Positioning Applications

This paper presents a new miniaturized patch antenna design for GNSS applications with low phase center variation and high circular polarization purity. The phase center variation values of this antenna enable positioning performance to be equal when compared to bigger state of the art commercial antennas. It is found that the circular features as well as a small asymmetry caused by circular slot pairs, perpendicular to each other, can generate the wanted circular polarization results while maintaining the antenna compact. Anechoic chamber measurements validate the simulation results, showing return loss and axial ratio bandwidths of 3.42% and 0.83%, respectively, alongside wide axial ratio beamwidth of up to 184∘ (φ = 0∘), boresight cross polarization rejection of 19.2 dB and low phase center variation under 1.5∘ (θ = -70∘ to θ = 70∘). These results, specially phase center variation, in relation to the antenna dimensions, are an improvement when compared to a vast number of miniaturized patch antennas available in the literature and commercially The final overall antenna dimensions, including the ground plane, are 0.34λ × 0.34λ0 x 0.016λ0 where λ0 corresponds to the antenna’s working frequency in free space (1.575 GHz).