A dual-frequency ceramic spiral antenna with rectangle PBG structure array used for modern RFID system

Abstract

For wideband RFID systems, we designed a dual-frequency ceramic spiral antenna with rectangle PBG structure array, working well with respect to the main frequencies of 915 MHz and 2.4 GHz. The size of the antenna is minimized obviously, only 30 mm × 30 mm × 1 mm. The simulated results show that the working center frequency in lower and higher frequency sections are 0.95 GHz and 2.55 GHz separately, at which the return loss values S11 are -23.22 dB and -15.98 dB respectively. And for VSWR less than 2, the absolute antenna bandwidths apartly are up to 0.254 GHz (0.837 ̃ 1.091 GHz) and 1.02 GHz (2.157 ̃ 3.177GHz). Considering engineering processes, the influences of dielectric constant εr and thickness of circuit board on the performance of antenna are particularly studied. We also discussed the rectangle PBG structure array in detail, including its length, width and arrangement regulation. At last, the contrast analysis on different radiation characteristics of the antenna while being sticked on various materials has been done to validate the function stability.