This paper presents the switching techniques for trapezoidal dual loop antennas to improve the communication performance of Radio Frequency Identification (RFID) system at low frequency. The switching techniques use two sets of antennas in walk-through gate configuration in order that the RFID reader can activate two sets of antenna at different times. Both antennas were designed to yield the magnetic field covering the entire volume. The antenna prototype was fabricated and measured the percentage of volume to confirm the communication performance. The obtained percentages of volume in three principal axes are 100%. The experimental results verify the antenna capability in RFID system.
