A compact dual-band dual circularly polarized aperture-coupled patch antenna for RFID application

A compact dual-band dual circularly polarized aperture-coupled patch antenna for RFID application has been designed, manufactured and measured. The proposed antenna antenna is equipped with separated transmitting (Tx) and receiving (Rx) ports, which allows to choose the CP sense by simply changing the input port. The antenna has a total size of 176 x 176 x 9.2 mm3 and shows an 10dB impedance width of 40MHz (890-930 MHz) in the UHF band and 100 MHz (24002500 MHz) in the ISM band. The axial ratio are less than 3dB from 890-930 MHz and 1.1dB from 2400-2500 MHz. The measured isolation between the Tx and Rx ports are about 28dB and 29dB, at 915MHz and 2.45GHz, respectively.