A Hybrid Meandered Line-Slot Patch Antenna for On- and In-Metal RFID Tag Design

A novel hybrid patch antenna that is embeddable in metal is proposed for radio frequency identification (RFID) tagging applications. The antenna features a simple design, consisting of a meandered line and a complementary slot surrounding a shorted radiating patch. This hybrid patch antenna can easily achieve high compactness by tuning the dimensions of the meandered line. The complementary slot is also playing a crucial role in enhancing the broadside radiation by promoting fringing fields from the radiating patch. As a result, the tag antenna becomes less sensitive to the cavity walls at surrounding. The proposed tag antenna, with dimensions of 30 × 30 × 3.2 mm³, can achieve high realized gain of −0.6 dBi when placed on a 200 × 200 × 20 mm³ metal block or in a 100 × 100 × 10 mm³ recessed metallic cavity. Although reducing the cavity’s size and depth can cause antenna’s realized gain to deteriorate to −2.5 dBi, the antenna’s resonant frequency remains stable at 0.915 GHz across all simulations.