This paper presents a study of an innovative front-end for UHF Radio Frequency Identification (RFID) and Partial Discharge (PD) detection application. The front-end system mainly consists of a dual-band antenna, a diplexer, and a PD detection unit. As the antenna design is the major objective of this work, a novel cavity-backed monopole antenna is thus designed, fabricated and tested. Experimental results show that the antenna can cover 649 MHz to 702 MHz and 876 MHz to 1050 MHz, which could be applied for future RFID sensor systems of condition monitoring and fault diagnostics in electrical utilities.