4×4 Element UWB Dual-Polarized Aperture Coupled Microstrip Patch Antenna Array for Chipless RFID

One of the crucial components in a chipless RFID system is an ultrawide-band (UWB) reader antenna. To have a reliable tag measurement in a chipless RFID system, having a reader antenna with desired specifications is required. Those specifications are UWB operating frequency, high return loss, a high gain, two dual-polarized ports, and a uniform radiation pattern in near-field and near far-field of the antenna. In this paper, a UWB dual-polarized 4×4 element antenna array with a uniform excitation is proposed for dual-polarized and cross-polar chipless RFID tag measurements. To design this antenna array, a modified aperture coupled microstrip patch antenna element is utilized. The back-lobe level in the radiation pattern is reduced by adding a metal back-reflector. The promising simulation and measurement results of the antenna array are presented. It shows that the operating frequency range of the antenna is from 4.4 GHz to 6.8 GHz, and a maximum gain of 21 dBi is yield.