Slot Antenna Backed by a Quarter Cylindrical Cavity with a Tuning Slit Stub

A slot antenna backed by a quarter cylindrical cavity operating in 920 MHz-band was designed. The antenna was provided with a slot line for tuning in addition to the radiating slot in order to attempt the extension of the variation range of the input impedance. Next, it was schemed that an RFID chip having a complex impedance was directly loaded on the surface of the slot antenna. Then, a set of configuration parameters was sought related to the tuning stub for impedance matching by electromagnetic field simulations. As a result, it was confirmed that matching could be performed even with the chip having not 50Ω but a complex impedance by the tuning slot stub, and thereby that the slot antenna backed by a quarter cylindrical cavity could be used as an antenna for the RFID. A chip mounted prototype antenna was fabricated and its communication range was measured.