Highly Miniaturized Mircrostrip Antenna with Slots and a Superstrate for RFID Applications

Abstract

RFID Tags, typically, require ultra-small antennas and at 900 MHz most of the designs end up being meandered line wire antennas. These may not be suitable because such antennas are heavily influenced by the object on which they are placed. An antenna with a ground plane, such as a microstrip antenna, is a more suitable candidate in that scenario, however, typically micrsotrip patch antennas are large in size. In this paper, we introduce a highly miniaturized microstrip antenna with multiple slots and a superstrate with high-permittivity material. The size of the microstrip antenna at 900MHz is reduced by 87.5% as compared to a conventional rectangular microstrip patch antenna at 900MHz. The gain of the miniaturized antenna is 0.36dBi, achieving 40% efficiency, which is decent enough for short to medium range RFID applications.