Switched Microstrip Array Antenna for RFID System

Switched array antenna with six microstrip patch elements was designed and characterized for UHF RFID application. A hexagonal-shaped RF switching circuit board was developed to select one of the array elements to read RFID tags surrounding the RFID reader antenna. The designed switching network ports have exhibited isolation greater than 30 dB and insertion loss less than 2.4 dB. The polarization direction of the microstrip patch elements is arranged perpendicular to RF switching circuit board. The measured characteristics of each antenna element at 915 MHz include gain of 9.06 and 8.62 dBi, half power beam width of 60deg and 70deg at E-plane and H-plane, respectively. Total switched array antenna can scan 360deg with 60deg incremental angle.