Helical reflector antenna with a wideband CP for RFID reader

A novel helical reflector antenna is presented to cover the whole UHF RFID band (860~960 MHz). The proposed antenna has a ground reflector and is composed of two antenna layers which are connected by via to form a helical structure. The total length of the proposed antenna is 1~1.3 ¿ to have the higher antenna impedance. And the antenna gain is increased by using a ground reflector. The size of the proposed antenna is 200 × 200 × 35 mm³ similar to commercial RFID patch antenna with a high gain. It satisfies -10 dB return loss and 3 dB axial ratio in the RFID band. The measured antenna gain is approximately 6.5~9 dBic.