Polarization and Space Diversity Antenna Using Inverted-F Antennas for RFID Reader Applications

An orthogonal antenna is presented for reader applications of radio frequency identification (RFID) at 433 MHz. The antenna is composed of two 1 times 2 subarrays orthogonally placed on a ground plane. Two different feeding networks are introduced to control horizontal and vertical radiation current flows for each subarray, respectively. An inverted-F structure is used as a radiation element with vertical and horizontal currents flowing on the radiator, thereby obtaining two linear polarizations. Antenna gains are 3.71 and 3.43 dBi and isolation between the two input ports is less than 25 dB