A circular monopole antenna with two steps and an offset circular slot for passive UWB-RFID tag localization applications

This paper presents a circular monopole antenna with two steps and an offset circular slot for passive ultra-wideband (UWB) radiofrequency identification (RFID) tag applications. The proposed tag will be used as a backscatterer for UWB localization applications. The scattering characteristics of the proposed UWB RFID tag such as the radar cross-section (RCS) and time domain waveforms are theoretically studied using commercial software program. Three different kinds of loads, i.e. 50-Ω matched, short-circuit and open-circuit loads are simulated. The proposed UWB monopole antenna has been used because of its good omnidirectional radiation characteristics. Results show that the backscattering from the UWB monopole antenna mode and structural mode can be easily distinguished in time-domain.