Compact dual ports handheld RFID reader antenna with high isolation

A compact dual ports antenna with high isolation is proposed for handheld radio frequency identification (RFID) reader, which is rarely reported in open literatures. Different with conventional handheld RFID reader antenna with single port, the proposed antenna transmits and receives signal separately. The proposed antenna operating with full duplex mode can enhance effectively sensitivity of reader, as the strong transmitting signal of reader with single port is usually highly coupled with weak receiving backscatter signal of tag. The antenna utilizes aperture coupled patch structure that occupies less volume and provides further space-saving efficiency. The height of the proposed antenna is only 5.1 mm and the volume of that is 80 x80 x 5.1 mm(3), which is easy to integrate in handheld RFID readers. The antenna uses four symmetric coupling apertures to excite two orthogonal modes for dual polarized operation. High isolation of around -35 dB is obtained by proper arrangement of the length and position of the coupling apertures. The maximum measured return loss is -39 dB at 2.4 GHz and isolation is -47 dB at 2.4 GHz. The antenna is suitable for applications in handheld RFID readers. (c) 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:548-555, 2015.