Investigation of Circularly Polarized CPW Fed Antenna as a 2.45 GHz RFID Reader

In this paper, a bi-directional coplanar-waveguide (CPW)-fed antenna with circular polarization (CP) is investigated as a radio frequency identification (RFID) reader antenna. The antenna geometry is square and printed on one side of the FR4 substrate only, which consumes an overall dimension of
$60\times 60$
mm2 with a thickness of 1.5 mm. The simulated and measured parameters of the antenna are in agreement with an impedance bandwidth (
$\text{S}_{11} < -10$
dB) of 40.2% (2.18–3.28 GHz) and ARBW (<3 dB) of 28.3% (2.03-2.7 GHz), respectively. The peak gain of the proposed antenna is 3.17 dBi in both ± z directions. An Arduino UNO-based open-source microcontroller setup is used for studying this antenna as an RFID reader antenna, along with a wireless module NRF24L01 module at 2.45 GHz with an external antenna (tag). The path loss between the tag and reader antennas is found to increase in the desired band due to interference exists.