Universal UHF RFID Rose Reader Antenna

Two meandered UHF RFID reader antennas are proposed. Both antenna structures are composed of a single loop on the top of FR4 substrate, which is meandered in the form of a rose to obtain compact size. The rose antenna is fed directly through microstrip line connecting the rose with the RF input. Down the microstrip feeding line a finite ground line placed on the bottom of the substrate. The antenna input impedance is controlled by adjusting the offset length of the ground line. Both antennas occupy areas of radius 25 mm and 21 mm, respectively compared to 72.5 mm for the conventional printed loop one. The measured bandwidths of the designed antennas cover the universal UHF frequency band of 840-960 MHz. Other radiation properties are found to be acceptable for both proposed antennas. Therefore, the proposed fabricated antennas are cheap, compact and universal for UHF RFID applications reader worldwide.