Gain tunability of graphene patch antennas for the ISM band at 24 GHz

In this paper, we present a coplanar patch antenna (CPA), based on a graphene monolayer deposited on a thin film of zirconium-doped hafnium oxide ferroelectric (HfZrO), working at 24 GHz. The proposed antenna has been designed, simulated, fabricated and measured according to the requirements of an indoor localisation system based on a Frequency-Modulated Continuous-Wave (FM-CW) radar in the 24 GHz (24-24.25 GHz) ISM band with small codified tags to add identification functionality. The graphene CPA (GCPA) shows a 3 dB-enhancement of the gain in the direction of maximum radiation when applying a DC bias of -25 V. Then, a realistic case of study with a $4\times 4$ array is presented, showing the feasibility of the G-CPA for a 24 GHz-radar suitable for next-generation 5G telecommunications systems.