Tunable Compact UHF RFID Metal Tag Based on CPW Open Stub Feed PIFA Antenna

Table 1

Requirements for designing a UHF RFID tag antenna.

Requirements of UHF RFID tag antenna design	Effects of improvement
	Read range	Cost	Reliability
(1) Good impedance matching	√
(2) High antenna gain	√
(3) Wide bandwidth	√		√
(4) Broadside radiation pattern	√		√
(5) Compact size and shape		√
(6) Low manufacture cost		√
(7) Easy for testing and tuning	√	√	√
(8) Stable performance for use	√		√