Design of Different Slotted Microstrip Patch Antenna for Rfid Applications

A compact cross, circular and square shaped slotted microstrip patch antennas are designed for circularly polarized (CP) radiation. Asymmetric, cross-shaped slot is embedded along one of the diagonal axes of the square patch for CP radiation and antenna size reduction. The designed antenna is contrived by using RT-Durid 5880 substrate . The design simulation and optimization is done by ADS software.The simulated return loss of this proposed antenna is less than -25dB at 2.5GHz with a bandwidth of 3MHz which is most suitable for RFID application. The overall size of the antenna with CP radiation can be reduced by increasing the perimeter of the symmetric cross-shaped slot within the first patch quadrant of the square patch. The circular polarization and radiation pattern parameters are compared for square, circular and cross shaped antennas. The simulated gain is more than 5dBi for all three antennas. The return losses of the measured results are in agreement with simulated results, the measured S parameters and radiation pattern showed that the proposed design is suitable for RFID frequency regions.