Polarization-Independent Gain Enhancing Metalens for GNSS L5 Band

This paper presents the design and analysis of a phase gradient metalens for gain enhancement with focused beam in broadside direction and operates at the L5 frequency band (1.176 GHz) for Global Navigation Satellite System (GNSS) applications. The planar lens has 20 × 20 array configuration and transforms the phase profile of the electromagnetic wave propagating through it by providing varying phase response. It is a 1-bit phase quantized lens with bit-0 and bit-1 meta-atoms consisting of three identical layers separated by an air gap of 44 mm. The designed lens is highly polarization-insensitive and has a size of 600 mm × 600 mm. The proposed lens has a focal length of 300 mm and uses a vivaldi antenna as the feed source resulting in f/D ratio of 0.5. The proposed lens improves the gain of the feed antenna by 9.23 dB and thus the maximum gain of 15 dBi is achieved in the broadside direction at 1.176 GHz. This results in the beamwidth reduction by 52.4 degree resulting in a broadside beamwidth of 23.9 degree and improvement in side lobe level by 6.7 dB from 9.1 dB to -15.8 dB.