Determination of Radiation Efficiencies for a Prototype with Impedance Bandwidth of 400 MHz in Free Space and 480 MHz on a Metallic Surface

RFID technology is widely used in a variety of service industries, including distribution logistics, manufacturing firms, and commodities flow systems. This is because RFID is versatile, as it can help with tracking, identification, automatic data collecting, and access control. This work presents a small and efficient antenna that can be used for active radio frequency identification (RFID) tags. The suggested antenna comprises a slotted patch positioned on an FR4 substrate, a microstrip line (feeding), and a foam spacer with a volume of merely
$60.02\ \text{mm} \times 50.33\ \text{mm}\times 6.09\ \text{mm}(0.48\lambda_{0}\times 0.40\lambda_{0}\times 0.048\lambda_{0})$
where
$\lambda_{0}$
represents the wavelength at the center frequency. When positioned on a metallic surface, it functions as a patch, whereas in free space it acts as a dipole. A prototype with an impedance bandwidth of 400 MHz (2.29-2.65 GHz) in free space and 480 MHz (2.30-2.77 GHz) on a metallic surface has been constructed and evaluated. The radiation patterns, peak gains, and radiation efficiencies recorded in these two circumstances are given.