Diversified path loss performance of dual-Polarised MIMO antenna in sub-6 GHz for RFID applications

Abstract

ABSTRACT In this paper, the path loss performance of an eight-port Multiple-In-Multiple-Out (MIMO) antenna consisting of four circular slots radiator-based antenna elements is investigated in 3.5–3.75 GHz range for utilisation as an RFID tag and reader antenna. First, the S-parameters between the ports of two proposed MIMO antennas are measured in four channels of spatial diversity; one direct line-of-sight (LOS) and three indirect LOS in an anechoic chamber, each for the horizontal and vertical polarisation schemes at two distances, 5 and 25 cm, and the path losses between the ports of MIMO antennas are evaluated. Then, the path losses between the same MIMO antennas are obtained in a laboratory environment, which are higher by about 5–10 dB than those in the anechoic chamber and so, these losses are more dependent on the antenna position and nearby objects. The tag power sensitivity and the tag (read) range for the presented MIMO antenna are found to be more power level dependent than frequency dependent. The reported results confirm the performance of proposed MIMO antennas for RFID applications in addition to 5 G communications.